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Preface

High entropy alloys (HEAs) are multicomponent equiatomic or near equiatomic alloys. They

have high configurational entropy due to which they tend to form solid solutions with simple

crystal structures. Prof. S. Ranganathan is the first to mention about these alloys in open

literature in his paper on “Multimetallic cocktails” published in 2003. Prof. J.W. Yeh has been

working on these alloys since 1995, but the first journal publication from his group on these

exciting alloys appeared in 2004. Interestingly, Prof. B. Cantor has also been independently

working on these alloys since 1981, but published his work in a journal only in 2004. In the

last decade there have been a lot of reports in this field including a recent book of Elsevier by

B.S. Murty, J.W. Yeh and S. Ranganathan.

There are a number of fundamental issues that need to be understood in these materials, such

as phase selection, lattice distortion, microstructure, thermal stability, deformation behavior,

diffusion, thermodynamic properties, processing challenges, etc. Though there is increasing

number of reports indicating some interesting properties of these materials, a complete

evaluation of the wide spectrum of properties of these materials is essential before their

potential for various applications can be established.

Globally there is an initiative to start a consortium for understanding these materials in the form

of Centre for Complex Concentrated Alloys (C3A). In India, there are only a few groups

working in this area. Capabilities exist in the country in the areas of first principle calculations,

MD simulations, thermodynamics, phase field modeling, synthesis, processing,

characterization, property evaluation and component development. There is a need to bring to

these people together in order for the country to make significant contributions in this field.

This workshop has been successful in bringing together scientists with expertise ranging from

first principle calculations to processing and applications, so that they look at the issues that

need to be addressed and the direction that should be taken in the coming decade in order to

not only arrive at a better fundamental understanding but also develop a few possible

applications of these alloys. This is the first meeting on HEAs in India.

We are grateful to all the participants who have come enthusiastically from long distances to

participate in this workshop. Our special thanks to overseas participants, Prof. J.W. Yeh, Prof.

Chris Berndt, Prof. Rajiv Mishra and Dr. Dan Miracle for the value they gave to this workshop.

We are grateful to Prof. Brian Cantor for taking his precious time out and giving a video

message for the participants of the workshop.

We are grateful to Boeing for being the main sponsor for this workshop. We are also thankful

to Department of Science and Technology, Defence Research & Development Organisation,

Government of India, GE, Anton Paar and Hysitron for their wholehearted support to the event.

We are confident that this workshop will be an enriching experience to every participant.

M Kamaraj, BS Murty, Ravi Sankar Kottada

KC Hari Kumar, Srinivasa Rao Bakshi

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National Workshop on

High Entropy Alloys: Prospects and Challenges

Organised by

Department of Metallurgical and Materials Engineering, IIT Madras

in association with

Boeing

March 28-29, 2015, IC&SR Auditorium, IIT Madras

Programme

March 28, 2015

08.30 Registration

09.00 Inaugural Session

Welcome: KC Hari Kumar, HOD In-charge, Dept. of MME, IITM

Welcome Remarks: Bala K Bharadvaj, Boeing India

Introduction to the workshop: BS Murty, IIT Madras

Presidential Remarks: S Ranganathan, IISc Bangalore

Inaugural Address: JW Yeh, NTHU Taiwan

Physical metallurgy of high-entropy alloys

Video Message by Brian Cantor, Bradford University, UK.

Vote of Thanks: Ravi Sankar Kottada, IIT Madras

10.00 Session 1: Basics

Chair: R Krishnan, Bangalore

10.00 S Ranganathan, IISc Bangalore

Solid Solutions - their limits and extensions

10.15 D Miracle, US Air Force Base, USA

Accelerated discovery and development of multi-principle element alloys via ICME

10.30 Rajiv Mishra, University of North Texas, USA

Some observations on unique aspects of mechanical behavior of high entropy alloys

10.45 Tea Break

11.15 Session 2: Basics II

Chair: Rajiv Mishra, University of North Texas, USA

11.15 BS Murty, IIT Madras

Excitement and challenges in the field of high entropy alloys

11.30 Chris Berndt, Swinburne Uni., Australia

Thermal spray routes towards achieving high entropy alloy phase structures

11.45 KC Harikumar, IIT Madras

Challenges in thermodynamic modelling of multicomponent systems

12.00 Lunch

13.00 Session 3: Synthesis & Processing

Chair: NK Mukhopadhyay, IITBHU, Varanasi

13.00 A Subramanian, IIT Kanpur

Orientational high entropy alloys

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13.15 SR Bakshi, IIT Madras

Effect of thermo-mechanical processing on NiTiCuFe multicomponent alloys

13.30 Pinaki Bhattacharjee, IIT Hyderabad

Thermo-mechanical processing of FCC CoCrFeMnNi high entropy alloy

13.45

Discussion on Session Topics

Moderator: AH Chokshi, IISc Bangalore

16.15 Tea Break

16.45 Poster Session

18.00 Departure for Dinner Venue

March 29, 2015

09.00 Session 4: Characterization, Properties & Applications

Chair: Chris Berndt, Swinburne Uni., Australia

09.00 R Krishnan, Bangalore

HEAs for AUSC plants, radiation environment and gas turbine engines

09.15 James D Cotton, Boeing Research & Technology, Seattle, USA

High entropy alloys: potential for airframe applications

09.30 KG Pradeep, RWTH Aachen, Germany

High entropy alloys to massive solid solution alloys: trend in complex alloy design

09.45 Joysurya Basu, IGCAR, Kalpakkam

Analytical microscopy for understanding structure and chemistry of multicomponent

alloys

10.00 R Koteswara Rao, Univ. of Hyderabad

Structural details, phase stability and mechanical properties of microcrystalline and

nanocrystalline Ti-Ni-Cr-Co-Fe high entropy alloy

10.15 S Abhaya, IGCAR Kalpakkam

High entropy alloys: Probing defects using positrons

10.30 Tea Break

11.00 Session 5: Characterization, Properties & Applications

Chair: VS Raja, IIT Bombay

11.00 Ravi Sankar Kottada, IIT Madras

Thermal stability and mechanical behaviour of high entropy alloys (HEA)

synthesized by mechanical alloying and spark plasma sintering

11.15 Vinod Kumar, MNIT Jaipur

Synthesis and characterization of light weight high entropy alloys

11.30 K Biswas, IIT Kanpur

High entropy alloys: pertinent issues on processing and stability

11.45 K Siva Prasad, NIT Trichy

Studies on CNT reinforced nanocrystalline AlCrCuFeNiZn high entropy alloy

composite

12.00 Lunch

13.00 Session 6: Modelling & Simulation

Chair: Umesh Waghmare, JNCASR, Bangalore

13.00 G Phanikumar, IIT Madras

Challenges in extending IRF concept in the solidification of multicomponent alloys

13.15 Sankara Subramanian, DMRL, Hyderabad

Challenges in the atomistic modeling of multicomponent alloys

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13.30 Abhik Chowdhury, IISc Bangalore

Microstructure evolution in multi-phase, multi-component alloys

13.45 Jatin Bhatt, VNIT Nagpur

Thermodynamic modeling for predicting metallic glass formation in high entropy

alloys

14.00 Tea Break

14.30 Discussion on Session Topics

Chair: KC Hari Kumar, IIT Madras

16.00 Way Forward & Conclusion

Chair: S Ranganathan, IISc Bangalore

Poster Session

S.No Name

1. Ameey Anupam, IIT Madras

Microstructural characterization of plasma sprayed high entropy alloy coatings

2. S Praveen, IIT Madras

Phase evolution, densification, and compressive properties of high entropy alloys

3. R Lavanya, IIT Madras

Alloying and phase evolution in refractory CrMoNbTiW high entropy alloy

4. Satish Idury, VNIT Nagpur

Design of high entropy metallic glass compositions from invariant reactions predicted

by CALPHAD methods through PHSS parameter

5. Anoop K, IIT Madras

Carbide formation during synthesis of Co-Cu-Fe-Mn-Ni-W multicomponent alloys by

mechanical alloying and spark plasma sintering route

6. Nandhini Singh, IIT BHU

Synthesis and characterization of FeAlZnCrCuMgSi and FeAlZnCrCuMgMn high

entropy alloys by mechanical alloying

7. Vikas Shivam, IIT BHU

Synthesis and characterization of Fe-Al-Zn-Cr-Cu-Mg and Fe-Al-Zn-Cr-Cu-Mg-Co

high entropy alloys by high energy ball milling

8. Tazuddin, IIT Kanpur

An ICME approach for development of ductile single phase high entropy alloy

9. Tarak Nath Maity, IIT Kanpur

Phase separation in mechanically alloyed high entropy alloys

10. Rahul Mane, IIT Hyderabad

Powder metallurgy of high entropy alloys

11. GD Sathiaraj, IIT Hyderabad

Effect of starting grain size on thermos-mechanical processing response of

CoCrFeMnNi high entropy alloy

12. ER Reddy, IIT Hyderabad

Microstructure and texture evolution during hot deformation of equiatomic high

entropy CoCrFeMnNi alloy

13. G Ramya Sree, University of Hyderabad

Understanding structural evolution and associated mechanical behaviour in a

Nanocrystalline AlCrCuCoFeNi high entropy alloy system

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14. Akanksha Dwivedi, University of Hyderabad

Synthesis and mechanical properties of Ti-V-Cr-Zn-Nb multi-component high entropy

alloy

15. Abhijit, University of Hyderabad

Structural stability of nanocrystalline multi-component Ti-Ni-Cr-Co-Fe alloy

16. Anand Shekar R, IIT Madras

Effect of thermo-mechanical processing on the microstructure and mechanical

properties of Ti-Al-Ni-Cr-Co based high-entropy alloys

17. Rameshwari Naorem, IIT Kanpur

Symmetry considerations for computation of orientational entropy in Jahn-Teller

active systems

18. K Guruvidyathri, K.C. Hari Kumar and B.S. Murty, IIT Madras

Phase prediction in multicomponent systems through CALPHAD method: A case

study on Co-Cr-Fe-Ni System

19. S Ranganathana, S Kashyap1, C Chattopadhyay2, A Takeuchi3, Y Yokoyama3, BS

Murty2, 1IISc Bangalore, 2IIT Madras and 3Tohoku University, Japan

Amorphisation by destabilisation of binary crystalline intermetallic compound with

equiatomic multicomponent substitution

20. Chinmoy Chattopadhyay and BS Murty, IIT Madras

Kinetic model for prediction of phase formation in high entropy alloys

21. K Praveen Kumar1 M Gopi Krishna2 J Babu Rao3 NRMR Bhargava3

1R.V.R. & J.C. College of Engineering, Guntur, 2ANU College of Engineering

&Technology, Guntur, 3College of Engg., Andhra University, Visakhapatnam

Microstructural and mechanical behaviour of 2024 Aluminium - high entropy alloy

composites

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Oral Presentation Abstracts

8

Physical Metallurgy of High-Entropy Alloys

Jien-Wei Yeh

Department of Materials Science and Engineering

National Tsing Hua University, Hongkong

Two definitions of High-Entropy Alloys (HEAs), based on composition and entropy, are

reviewed to clarify misunderstandings. Four core effects, i.e. high entropy, sluggish diffusion,

severe lattice distortion, and cocktail effects, are mentioned to show the uniqueness of HEAs.

Then, current state of Physical Metallurgy is discussed. Physical metallurgy is a branch of

materials science, which focuses on the relationship between composition, processing, crystal

structure and microstructure, and physical and mechanical properties. The progress of physical

metallurgy is over one hundred years and the underlying principles were thought to be mature.

However, this was based on the observations on conventional alloys. As phase formation of

HEAs is entirely different from that of conventional alloys, physical metallurgy principles may

need to be modified for HEAs.

Development of new HEAs was mainly concerned with the trials of different compositions and

processing, and the analyses of their properties and microstructure in the first decade after the

birth of HEAs in 2004. Now it is time to investigate physical metallurgy of HEAs for an in-

deep understanding HEAs, not only satisfying scientists’ curiosity but also helpful in designing

and controlling HEAs.

Every aspect of physical metallurgy needs to be re-checked in the world of HEAs and the

bridges from conventional alloys to HEAs need to be built in order to get a better understanding

of alloys. In this presentation, thermodynamics, kinetics, structure and properties of HEAs are

briefly discussed relating with the four core effects of HEAs. Among these, severe lattice

distortion effect is particularly emphasized since it exerts direct and indirect influences on

many aspects of microstructure and properties. Because a constituent phase in HEAs is

ordinarily not based on one major element and its matrix can be regarded as a whole-solute

matrix, every lattice site in the matrix has atomic-scale lattice distortion. In such a distorted

lattice, point defects, line defects, and planar defects are different from those in conventional

matrices in terms of atomic configuration, defect energy, and dynamic behavior. As a result,

mechanical properties relating with Young’s modulus, solid solution hardening, serration

behavior, work hardening, grain size strengthening, twinning-induced strain hardening,

ductility, creep, and fatigue initiation and propagation are influenced by such distortion. In

addition, physical properties relating with lattice constant, diffusion, X-ray diffraction, melting

temperature, electron mobility, electrical conductivity, thermal conductivity, magnetism,

temperature coefficient, and damping capacity also have different trends in HEAs. Most

importantly, this presentation points out that lots of future works are required to build suitable

mechanisms and theories correlating composition, microstructure and properties for HEAs.

Only these understandings would make it possible to complete the physical metallurgy of the

alloys world.

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Solid Solutions - Their Limits and Extensions

S Ranganathan

Department of Materials Engineering

Indian Institute of Science, Bangalore 560012

The first alloys encountered by mankind were native alloys like electrum and tumbago. These

were followed by the serendipitous discovery of alloys of copper with arsenic in 3000 BCE.

These were all solid solutions. It is interesting to note that at the beginning of the third

millennium CE studies of high-entropy alloys have brought solid solutions once again to centre

study.

The scientific understanding of the formation of solid solutions was first given by Hume-

Rothery in his classic 1926 paper. In phase formation he pointed out that size, electronegativity

and valence played important roles and identified factors responsible for the formation of solid

solutions. In addition, he stated that for forming a continuous series of solid solutions the metals

must have the same crystal structure.

David Pettifor in 1984 took the next major step of adding a fourth factor of bond orbitals. He

gave each element a Mendellev Number and constructed Pettifor Maps. This has been a

powerful device first applied by him to explain the formation of crystalline intermetallics. This

was extended to quasicrystals by Jeevan, Ranganathan and Inoue and to glasses by Takeuchi,

Inoue, Murty and Ranganathan.

In this presentation, we extend a preliminary study by Biswas and Ranganathan to equiatomic

multicomponent high-entropy alloys. It is possible that the cocktail effect is responsible for

extending solid solutions beyond that in lower order systems, often overriding the requirement

of the same crystal structure. Future lines of investigation will be pointed out.

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Accelerated Discovery and Development of Multi-Principle Element Alloys

via ICME

D.B. Miracle, O.N. Senkov, J. D. Miller and C. Woodward

Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson

AFB, Ohio 45433, USA

Multi-principle element (MPE) alloys (also called high entropy alloys) have 5 or more elements

at roughly equivalent concentrations. The vast number of new alloy systems created by this

approach gives dramatic new opportunities for discovery and development. However, the

immense number of alloy systems also represents the most significant technical barrier. A

palette of 40 metal elements offers over 10^10 MPE alloy systems, so that fundamentally new

methods are needed to design and evaluate alloy systems rapidly, systematically and

effectively. A 3-stage approach is described to rapidly screen and evaluate vast numbers of

MPEs for aerospace applications. CALPHAD methods that calculate phase equilibria are

integrated with high-throughput experiments on materials libraries with controlled composition

and microstructure gradients. Much of this evaluation can be done now, but key components

are missing. This ICME methodology will be described, current results will be presented, and

required future efforts will be outlined.

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Some Observations on Unique Aspects of Mechanical Behaviour of High

Entropy Alloys

Rajiv S. Mishra, Nilesh Kumar, Mageshwari Komarasamy

Center for Friction Stir Processing, Department of Materials Science and Engineering,

University of North Texas, Denton, TX 76203, USA

High entropy alloys are highly concentrated solid solution alloys that exhibit exceptional

mechanical properties. In this presentation, the underlying fundamental deformation science

will be highlighted. Three distinct areas of focus will be, (a) strain rate dependence, (b) role of

nanotwinning, and (c) grain size dependence. A comparison with conventional alloys helps in

delineating the micromechanisms. Some thoughts for future research directions will be shared.

12

Excitement and Challenges in the Field of High Entropy Alloys

B.S. Murty

Department of Metallurgical and Materials Engineering

Indian Institute of Technology Madras, Chennai- 600 036

High entropy alloys (HEAs) are a new class of multicomponent equiatomic (or near

equiatomic) alloys, which form simple solid solutions due to their high configurational entropy.

The formation of nanocrystalline HEAs has made them more interesting due to their

fundamental and technological importance. The simple structures, high thermal stability of the

structures, exceptional mechanical properties, both at ambient and high temperatures, low

diffusivities, good corrosion and oxidation resistance are all quite exciting to the scientists in

the field.

The challenges in the field include prediction of phases that can form for a given combination

of elements and the influence of the processing route on phase formation. A number of

thermodynamic and topological parameters are being proposed by many to predict phase

formation. The efficacy of these parameters in predicting the phase formation in a variety of

HEAs needs to be established. As of now there appears to be no single parameter, which can

be universally applied to a wide range of HEAs. It is also important to know the conditions a

given HEA forms an amorphous solid solution instead of a crystalline one. It is also challenging

to understand whether the phases formed are truly entropy stabilized or kinetically stabilized

due to low diffusivities in these multicomponent systems. It is also important to note that all

multicomponent equiatomic alloys do not lead to the formation of single phase solid solution

or for that matter mixture of solid solutions. In a few cases, they have shown the formation of

intermetallic phases and in some cases phase separation of certain elements with high positive

enthalpy of mixing with other elements in the alloy. It is important to understand the

decomposition behaviour that occurs on a nanoscale in a number of HEAs.

13

Thermal Spray Routes towards Achieving High Entropy Alloy Phase

Structures

Christopher C. Berndt*, Andrew S.M. Ang and Mitchell L. Sesso

Swinburne University of Technology, H66, P.O. Box 218, Hawthorn, Victoria 3122, Australia

*Adjunct Professor, Dept. of Materials Science and Engineering, Stony Brook University,

Stony Brook, NY11794, USA

AmeeyAnupam, S. Praveen, Ravi Sankar Kottada, B.S. Murty

Department of Metallurgical and Materials Engineering, Indian Institute of Technology

Madras, Chennai 600036, India

High Entropy Alloys (HEAs) are known for their high temperature microstructural stability,

enhanced oxidation and wear resistance properties. HEAs have been deposited as a surface

coating in this work by thermal spray methods. Our original aim was to investigate HEAs as

an alternative bond coat material for a thermal barrier coating system. Therefore,

nanostructured HEAs that were based on AlCoCrFeNi and MnCoCrFeNi were prepared by ball

milling and then plasma sprayed. Splat studies were assessed to optimize the appropriate

thermal spray parameters and spray deposits were prepared. Subsequently, the microstructure

and mechanical properties of two HEAs coatings of different composition were characterized

and compared to conventional plasma sprayed NiCrAlY bond coats.

Much has been learned concerning the microstructural and phase stabilities of the so-formed

HEA coatings. The presentation in this workshop will focus on our current state-of-the-art

knowledge as well as future directions where we seek to fill in the gaps concerning the

technology and science.

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Challenges in Thermodynamic Modelling of Multicomponent Systems

K.C. Hari Kumar

Department of Metallurgical and Materials Engineering

Indian Institute of Technology Madras, Chennai- 600 036

Calphad provides a very efficient framework for computing phase stability related information

concerning multicomponent materials. Several Gibbs energy databases and computational

thermodynamic tools are available for this purpose. Most of the commercial databases are

“principal element centric”, therefore not suitable for dealing with phase stability of equiatomic

multicomponent alloys, although there is increasing evidence that there is nothing unusual

about these alloys from a thermodynamic point of view. In this talk I will outline the challenges

in constructing Gibbs energy databases for dealing with multi-principal element alloys.

15

Orientational High Entropy Alloys

Anandh Subramaniam Materials Science and Engineering

Indian Institute of Technology Kanpur, Kanpur-208016

In high entropy alloys (HEA) the configurational entropy, due to the presence of multiple

elements, stabilizes a disordered solid solution (DSS) in preference to the possible formation

of compounds. In the current work, we identify cluster compounds (of the type AM4X8) as

orientational analogues of HEA. In cluster compounds, the role played by ions in the NaCl

structure (Na+ & Cl–) is played by two kinds of clusters in the compound (cubane: (Mo4S4)5+

& tetrahedron: (GaS4)5–). In cluster compounds orientational disorder increases the entropy and

plays the role analogous to positional disorder in HEA. In the specific example of the GaMo4S8

compound, at temperatures greater than 50K, the entropic benefit more than makes up for the

strain energy cost and stabilizes the disordered phase in preference to an orientationally ordered

compound (of lower symmetry).

16

Microstructure and Mechanical, Corrosion and Oxidation Properties of

NiTiCuFe Multi-Component Alloy

Anand Sekhar R1, Niraj Nayan2, G Phanikumar1, Bakshi S R1 1Department of Metallurgical and Materials Engineering,

Indian Institute of Technology, Madras, Chennai – 600036 2Vikram Sarabhai Space Centre, Thumba, Thiruvananthapuram, Kerala-695022

Alloying can make drastic changes in mechanical and chemical properties. In conventional

alloys, addition of other elements is usually restricted to only small amounts. High Entropy

Alloys having generally more than five elements in equiatomic compositions show an

enormous increase in configurational entropy making it thermally stable even at high

temperatures. NiTiCuFe high entropy alloy was prepared using a medium frequency induction

melting furnace. Thermodynamic criteria show that this composition can form single phase.

Thermo-mechanical processing studies were carried out using Gleeble®3800 to understand the

effect of high temperature deformation on the microstructure and mechanical properties of

NiTiCuFe HEA. Samples were subjected to deformation at 800, 900 and 1000 °C. Results show

good compressive strength up to 1000°C. Room temperature compressive test conducted on

the samples shows good compressive strength. The phase evolution after thermo-mechanical

processing was studied using XRD. As cast structure showed a mixture of BCC and FCC phase.

Thermo-mechanical processing favours the formation of three phases Cu-Ni FCC phase, Fe2Ti

Laves phase (C14) and Ni3Ti intermetallic (D024). Microstructural characterization using SEM

and TEM confirms the presence of three phases. Effect of phase evolution on the mechanical

properties was studied using nano-indentation with a Berkovich indenter. Elastic modulus and

hardness of the phases were measured from load the displacement curves. Results explain the

contribution of each phase on the mechanical property. Microhardness was also measured on

the samples before and after compression. Results shows good hardness values for all the

samples. Corrosion behaviour of the alloy was studied using 3.5 wt.% NaCl in distilled water.

Results show good corrosion resistance comparable with that of stainless steel.. Oxidation

study was also conducted on the samples at 800, 900, 1000 and 1100oC. Results indicate good

oxidation resistance up to temperatures of 900oC.

17

Thermo-Mechanical Processing of FCC CoCrFeMnNi High Entropy Alloy

P.P. Bhattacharjee*

Department of Materials Science and Metallurgical Engineering,

Indian Institute of Technology Hyderabad, Hyderabad

Ordnance Factory Estate Yeddumailaram 502205

The thermo-mechanical processing behavior of equiatomic FCC CoCrFeMnNi high entropy

alloy (HEA) was studied with particular emphasis on the microstructure and texture formation.

For this purpose, the alloy was cold-rolled to 90% reduction in thickness and isochronally

annealed for one hour at temperatures ranging from 700°C to 1000°C. The deformation

texture of the heavily cold-rolled material revealed the presence of a strong brass component

({110}<112>), typical of low stacking fault energy materials. Near ultrafine microstructure

was observed after annealing at low temperatures. The annealing texture was characterized by

the presence of α-fiber, retained deformation texture components, brass recrystallization

component ({236}<385>) and several other different components. However, the volume

fraction of different components was not significantly affected by the annealing temperature.

The observed microstructural and textural changes were compared and contrasted with other

model low SFE alloys to highlight the unique behaviour of the HEA.

18

HEAs for AUSC plants, Radiation Environment and Gas Turbine Engines

R. Krishnan

Ex. BARC & DRDO

High entropy alloys with their significantly enhanced physical and mechanical properties have

revolutionised the materials world. Most of these alloys have solidified either in the FCC or

the BCC structure, or with one of them as the major phase. It has also been shown that FCC

alloys are soft and ductile, while their BCC counterparts are hard but brittle. When one looks

for applications in specific areas, one needs to judiciously design the alloy to meet the intended

requirements.

This presentation deals with the selection of possible HEAs in three areas, namely advanced

ultra-super critical (AUSC) coal powered stations, radiation environment and aero gas turbine

engines. With regards to the AUSC boiler tubes, the chosen HEA should have better fireside

corrosion and steam side oxidation resistance than the materials already chosen such as Incoloy

740 or Haynes 282. Ductile FCC HEA would meet the requirement, provided it also has the

requisite high temperature (> 8500C) mechanical properties. Evaluating the data so far available

on HEAs, the suggestions for AUSC applications are: 1. Oxide Dispersion Strengthened low

stacking fault energy FCC alloy such as FeCrCoMnNi with Y2O3 dispersions 2. High strength

FeCoCrNi2Al alloy with minor additions of Mo, Ti or Si either singly or in combination 3. FCC

HEA matrix with B2 dispersions such as AlCoNiFeTi0.4 & AL0.3CoCrFeNi.

As for as radiation environment is concerned, a BCC structure is better as compared to a FCC

because the former can accommodate radiation induced point defects more easily. Presently

zirconium base alloys are used in thermal reactors, while ferritic steels are used in fast reactors

as fuel clads, but these do not have adequate long time radiation resistance to withstand

increased fuel burn-up. BCC high entropy alloys with adequate ductility may be a better choice.

Component elements in the HEA should decrease the SFE of the alloy such that the material

deforms by nano twinning. Nano crystalline structures also assist in this process. The

suggestion made with respect to fast breeder reactor fuel clad (may also be suitable for GEN

IV reactors) is a combination of FeAlCrMoSiTi, not necessarily in equal atomic proportions,

such that one ends up in a low SFE BCC alloy with adequate ductility and strength.

With regards to high pressure gas turbine engine rotors, the main requirement is high

temperature capability, with adequate creep resistance. While HEAs possess good mechanical

properties, creep resistance is obtained essentially by microstructural control. In this context,

multiphase alloys with a disordered (ordered) matrix and ordered (disordered) epitaxial

dispersoid may be beneficial. Thus an HEA from NbFeAlCrTiNiMo is worth trying. The

microstructure of HEAs like MoNbTaVW should be made multiphase with suitable alloying

additions, to make it ductile, while retaining its high temperature strength.

In the ultimate analysis, focus should be on treating HEAs as the base and making minor

additions to it to get the desired microstructure and mechanical properties.

19

High Entropy Alloys: Potential for Airframe Applications

James D Cotton1, Om Prakash2 1Boeing Research & Technology, Seattle, WA, USA

2 Boeing Research & technology India Centre, Bangalore

“High Entropy Alloys” are often characterized as alloys consisting of roughly equal

concentrations of at least five metallic elements and are claimed to favor close-packed,

disordered structures due to high configurational entropy. Such crystal structures, e.g. face-

centered cubic (FCC), hexagonal close-packed (HCP) and body-centered cubic (BCC), are

advantageous in that they should offer multiple active slip systems usually observed in ductile

metals and alloys. This opens the door to a large number of rich chemistries which would

otherwise contain such unacceptably large volume fractions of intermetallic compounds as to

not be useful in structural applications.

Despite some thermodynamic arguments for entropic stabilization of simple, disordered

phases, the high entropy alloys studied to date typically consist of combinations of elements of

known extensive solid solubility. For example, most investigated chemistries are based on a

cast CoCrFeNiX type base chemistry, where X = Al, Cu, Mo or Ti. Isolated research in other

systems, such as TaNbHfZrTi, has also been conducted. In both systems, FCC and/or BCC

crystal structures have been observed to predominate. This raises the question of the effective

ability of configurational entropy to extend the useful solid solubility range of the disordered

phases. Whether or not entropy plays a significant role in phase selection, the richness of the

alloy design space and the breadth of possible microstructures is fascinating, such that the

problem becomes more one of deciding on an alloy development direction. This leads to some

high-level questions. For example, what is the goal of a high entropy alloy development effort?

Can any of the alloys discovered to date compete both economically and technically with those

already available, and those in development? What is theoretically achievable in rich, multi-

component compositions? In this paper, Boeing work will be reviewed that has evaluated the

potential for low density airframe alloys, as well as a combinatorics-based model for predicting

complex alloy behavior in which over 600,000 possible equiatomic compositions containing

up to six components were evaluated. Commentary will be offered on potential directions for

future work.

20

High Entropy Alloys to Massive Solid Solution Alloys: Trend in Complex

Alloy Design

K. G. Pradeep1,2 1Materials Chemistry, RWTH Aachen University, Kopernikusstr.10, 52074, Aachen, Germany

2Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-str.1, 40237, Düsseldorf,

Germany

High entropy alloys (HEA) from its inception has attracted lot of attention due to developing

single phase solid solutions from multi-principal constituents. The interest therefore lies in

discovering and exploring the physical and mechanical properties arising from multi-

component solid solution strengthening. However, the HEA design as of today is very much

empirical and hence only a limited number of single phase solid solution forming systems has

been identified. In spite of the fact that the stability of identified single phase solid solutions is

still under question, the enormous efforts being employed in this field have provided limited

dividends. In order to overcome such deficiencies, the use of nonequiatomic HEA design has

been suggested which consistently delivers single phase solid solutions over a wide range of

compositions. Even though, the configurational entropy of non-equiatomic HEAs is much

lower than their equi-atomic counterparts, the as formed single phase solid solutions are highly

stable and exhibit outstanding mechanical properties. Hence, these new class of non-

equiatomic multi-component alloys could be termed as massive solid solution alloys owing to

their outstanding properties arising out of pure solid solution strengthening. The use of

quantum mechanically guided high throughput technology employed for the synthesis of non-

equiatomic HEAs will be presented and their outstanding mechanical properties will be

discussed.

21

Analytical Microscopy for Understanding Structure and Chemistry of

Multicomponent Alloys

Joysurya Basu

Physical Metallurgy Group

Indira Gandhi Center for Atomic Research, Kalpakkam-603102, Tamil Nadu, India

Analytical transmission electron microscopy provides an excellent opportunity to study

structure and chemistry of multicomponent alloys which is the key to microstructural

engineering and optimization of properties. Pertaining to the complex chemistry and variable

processing conditions, multicomponent alloys are often held up at local thermodynamic

minima. Detailed atomic resolution microscopy not only helps in understanding the phase and

the microstructure evolution, but may provide insight into the underlying mechanisms

operative along the evolution path. In the present talk, precipitation of carbide phases and their

conversion into oxy-carbides at a later stage in Fe-Co-Ni-Cr alloy as studied by STEM-EELS

would be discussed. Additionally, crystal nucleation in Zr-Cu-Ni-Al alloy and its relation to

polyhedral structures in the liquid phase as studied by quatitative high resolution electron

microscopy would be discussed in detail. In course of this presentation, an attempt would be

made to explain the fact that analytical electron microscopy not only helps in understanding

the phases and microstructures, it does help in understanding the operative underlying

mechanisms.

22

Structure, Phase Stability and Mechanical Properties of Microcrystalline

and Nanocrystalline Ti-Ni-Cr-Co-Fe High Entropy Alloy

Abhijit1, P. Sai Karthik2, Ravi C. Gundakaram2, G. Madhusudhan Reddy3 and

Koteswararao V. Rajulapati1* 1 School of Engineering Sciences and Technology,

University of Hyderabad, Hyderabad 500046, India. 2International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI),

Hyderabad 500005 3Defence Metallurgical Research Laboratory, Hyderabad 500058

High Entropy Alloys (HEA) are alloys having at least five principal elements and all the

principal elements are mixed in equiatomic ratios. HEAs usually form simple solid solutions

with fcc and/or bcc structures with no intermetallic compounds and hence have emerged as a

new type of advanced metallic materials. HEAs possess some excellent mechanical properties

and have great potential to be used as high temperature materials, coating materials requiring

high hardness and high wear resistance and corrosion resistance materials with high strength.

A multi-component TiNiCrCoFe high entropy alloy is synthesized using vacuum arc melting.

Structural details are probed using optical microscopy, XRD, SEM and TEM. Mechanical

characterization was done using Vickers microindentation and nanoindentation. Subsequently

the as-cast HEA is milled for 30 hours to attain nanocrystalline structure. The nanocrystalline

TiNiCrCoFe HEA is then sintered using Spark Plasma Sintering (SPS) at 0.5TM and 0.6TM,

and characterized using SEM, XRD and TEM, and also tested for various mechanical

properties. The results of both micro-crystalline and nano-crystalline Ti-Ni-Cr-Co-Fe HEA are

compared and discussed in detail.

23

High Entropy Alloys: Probing Defects using Positrons

S. Abhaya

Materials Science Group

Indira Gandhi Centre for Atomic Research, Kalpakkam-603 102

High entropy alloys (HEAs) are multicomponent equiatomic or near equiatomic alloys which

form solid solutions with simple crystal structures owing to their high configurational entropy.

Yeh et al. pointed out that the configurational entropy of a binary alloy is maximum when the

elements are in equiatomic proportions and that the configurational entropy increases with

increasing number of elements in a system. Furthermore, the low diffusivity of the atoms in

these multicomponent alloys restricts the formation of the number of phases. Because of the

unique equiatomic/near equiatomic composition, the HEAs are bestowed with high

strength/hardness, high thermal stability and good corrosion and oxidation resistance.

Defects play an important role in deciding the phase, microstructure and mechanical properties

of the high entropy alloys. So, with controlled thermomechanical treatment, one can alter the

nature of the defects present thereby changing the so called unique properties of the high

entropy alloy. Hence defect characterization becomes an important aspect of HEA. Positron

annihilation spectroscopy is an excellent non-destructive defect characterization tool.

This talk will give a flavour of how positron annihilation spectroscopy is useful in

understanding a) defect recovery and crystallization in arc melted FeCrCoNi alloy using

positron lifetime and b) implantation induced defect evolution and defect annealing in 1.5

MeV Ni implanted FeCrCoNi for two different doses using variable low energy positron beam.

24

Thermal Stability and Mechanical Behaviour of High Entropy Alloys

synthesized by Mechanical Alloying and Spark Plasma Sintering

Ravi Sankar Kottada

Indian Institute of Technology Madras, Chennai

The alloy designing of High Entropy Alloys (HEAs) is distinctively different from

conventional alloys. This new class of alloys usually consists of more than four elements mixed

in equi-atomic proportion, but form a few phases with simple FCC or BCC structures. Most

of these HEAs possess very high strength, outstanding thermal stability and excellent strength

retention at higher temperatures. Thus, the research in the area of HEAs has been progressing

at a rapid pace. In the present study, CoCrFeNi high entropy alloy was synthesized by

mechanical alloying and subsequently sintered in a spark plasma-sintering (SPS) unit. Phase

evolution during mechanical alloying and phase changes after SPS were studied using XRD

and SEM. Thermal stability of the microstructure is studied in the temperature range of 700 –

900C for durations of more than 500 h, which shows that these alloys are extremely stable at

temperatures greater than 0.5 Tm. Room temperature as well as high temperature mechanical

properties were studied under constant strain rate and under constant stress conditions. This

alloy exhibits very high compressive strength of ~2 GPa with plastic strain of 20%. Detailed

post-deformation microstructural characterization was done using XRD, SEM and TEM.

25

Synthesis and Characterization of Light Weight High Entropy Alloy

Jaibeer Singh1, Ornov Maulik1, Vinod Kumar1,2, * 1Department of Metallurgical and Materials Engineering, MNIT Jaipur - 302017

2Adjunct Faculty, Materials Research Centre, MNIT Jaipur - 302017

An AlMgFeCuCrNi based high entropy alloy was synthesized by mechanical alloying followed

by conventional sintering. Phase analysis at room temperature was investigated using X-Ray

diffraction and SEM. It has been found that two solid-solution phases with body-centered cubic

(BCC) and face-centered cubic (FCC) crystal structures form in this alloy. Effect of sintering

temperatures, such as 800°C, 850°C and 900°C, on phase evolution and hardness was studied

in detail.

26

High entropy alloys: Pertinent Issues on Processing and Stability

Krishanu Biswas

Department of Materials Science and Engineering,

Indian Institute of Technology Kanpur, Kanpur - 208016

Recently, the multicomponent HEAs have attracted a great deal of attention from both

academic as well as engineering world because of their ability to form FCC/BCC/HCP solid

solutions, unique microstructures and appealing properties. However, the HEA phase

formation and stability need to be properly investigated and a proper direction is needed to

make them useful for potential applications.

The selection of alloying elements and their composition play crucial role in phase selection.

Most importantly, formation of a single phase (FCC or BCC or HCP) is the critical issue that

needs to be researched upon. In the present investigation, we shall discuss about ICME

approach to select elements and their composition so that a single phase can be obtained in cast

alloys. The alloys systems obtained by ICME have further been investigated experimentally to

check whether the computational approach can effectively be utilized.

In addition, stability of HEA phases is also a critical issue if we can use them in future

applications. In this context, we shall highlight microstructural evolution as well as stability of

these novel alloys in this presentation. The specimens are prepared using both casting as well

as mechanical alloying followed by spark plasma sintering. The microstructural development

of the as processed and heated specimens of different alloy systems, CuZnTiFeCr,CuNi

TiFeCoCu and AlCuZnCoNi, AlCuCrNiFe will be dealt with. The microstructural evolution

will be discussed with detailed thermodynamical and diffusional calculations. The study will

show novel sinter aging technique to improve the hardness of these alloys, making and

stabilizing nanocrystalline grains of the HEA phases in the microstructure as well as

compositional control of the different HEAs required having good stability at high

temperatures.

27

Studies on CNT Reinforced Nanocrystalline AlCrCuFeNiZn High Entropy

Alloy Composite

N.T.B.N. Koundinya and K. Sivaprasad

Advanced Materials Processing Laboratory, Department of Metallurgical & Materials

Engineering, National Institute of Technology, Tiruchirappalli - 620015, Tamil Nadu, India

Elemental powders were milled for 30 h to form a solid solution of AlCrCuFeNiZn high

entropy alloy. To evaluate the effect of CNTs as reinforcement phase, CNTs were added in

different fractions in the last one hour of milling. The crystallite size reduced significantly

during initial stages of milling. The final crystallite size after 30 h of milling is around 15 nm.

Powders were hot compacted at 800C for 2 h under a compaction pressure of 500 MPa.

Relatively less densification was achieved (90-95%) because of large strain associated with

powders. The sintered samples exhibited separation of phases from single phase BCC to one

BCC (13%) and two FCC phases (38%-48% each). The hardness of the sintered alloy was ~

6.3 GPa and with increasing reinforcement the hardness reduced to 5.6GPa. This is attributed

to less densification associated with reinforcement. Indentation based fracture toughness was

evaluated on these samples. CNT reinforced samples clearly evidenced an enhanced fracture

toughness value, which is attributed to bridging of crack faces by CNTs. Hence, it can be

summarized that CNTs as reinforcement phase can enhance fracture toughness even in brittle

HEA samples.

28

Challenges in Extending IRF Concept in the Solidification of

Multicomponent Alloys

Gandham Phanikumar

Indian Institute of Technology Madras, Chennai

An in-depth understanding of the microstructure evolution can provide regimes of

microstructure stability for any newly discovered multi-component alloy. This will help in

limiting the uncertainties before the alloy is deployed in demanding applications. Predictive

capability in determining the microstructure evolution during solidification of alloys is possible

using either computer simulation or analytical calculations. Usage of phase-field simulations

coupled with thermodynamic and mobility databases are emerging as a popular technique to

predict microstructure evolution in technical / multi-component alloys. The analytical approach

to the same would involve coupling a morphological stability criterion and the solution of

diffusion field to arrive at the interface temperature of a given phase in a given morphology.

Interface response functions (IRF) embed the relationship between the interface temperature

on the local composition, gradients and relevant thermo-physical parameters. This method of

IRFs has been used earlier to successfully determine complete microstructure maps for alloy

systems such as Al-Cu and Al-Ni. In this talk, the challenges in extending this concept to the

solidification of multi-component alloys will be discussed. This involves different physical

properties that are required for the calculations, verification of the validity of underlying

assumptions in the theory and a set of controlled experimental studies.

29

Challenges in the Atomistic Modelling of Multicomponent Alloys

R. Sankarasubramanian

Defence Metallurgical Research Laboratory, Kanchanbagh P.O., Hyderabad – 500059

Integrating microstructrual modelling & simulation with experiments has become an essential

part of development of new materials. Material microstructure often spans several decades of

lengthscale (say, for example, in the case of nickel base superalloys, from a few atoms (~10-

10m) to a few centimeters (~10-2m)). Simulation of such microstructures requires multiscale

modelling, of which, atomistic modelling is an important constituent. Density functional theory

(DFT) based first-principles calculations, molecular dynamics and Monte Carlo simulations

are widely used atomistic modeling techniques. While each of the techniques has its own merit,

there are many challenges while addressing engineering alloys. For example, DFT technique

is best suited for ordered compounds but has to be used with care while studying disordered

alloys. Molecular dynamics and Monte Carlo simulations require accurate description of

interatomic interactions, which are generally not available for multicomponent alloys. In this

presentation, some of the key challenges in the atomistic modelling of multicomponent alloys

are discussed and possible solutions to overcome the challenges are highlighted.

30

Microstructure Evolution in Multi-Phase, Multi-Component Alloys

Abhik Choudhury

Department of Materials Engineering

Indian Institute of Science, Bangalore 560012

Microstructures are important building-blocks for new materials because; several physical

properties can be related to the patterns at the microscale. An important processing route in the

design of microstructures is through solidification, wherein, the self-organization of the

different phases and their morphologies can be engineered by altering one or many of the

several processing parameters (velocity, thermal gradients, convective currents etc.), as well as

the material constituents (alloy compositions, elements etc.). To perform this in a systematic

manner however, will require a good understanding of process→structure and

parameter→structure correlationships. In this regard, thermodynamically consistent phase-

field models describing microstructural evolution as a function of the process and material

parameters are useful.

In this talk I will present microstructural evolution, in binary and ternary alloys, encompassing

single-phase dendritic as well as multi-phase eutectic structures. In the context of

microstructural design of materials, while binary alloys provide a certain range of attainable

microstructures, these possibilities increase with the addition of each single element, thereby

the sample space for the engineering of different microstructures and therefore the achievable

properties from a given set of material constituents, becomes larger. I will utilize phase field

modelling as a tool for establishing process→structure and parameter→structure

correlationships in binary and ternary alloys, thus highlighting the utility of the phase field

method both in the context of ICME, as well as modelling of microstructures in high-entropy

alloys.

31

Thermodynamic Modelling for Predicting Metallic Glass Formation in

High Entropy Alloys

K.S.N. Satish Idury1, B.S. Murty2 and Jatin Bhatt1*

1Department of Metallurgical and Materials Engineering, V.N.I.T Nagpur 2Department of Metallurgical and Materials Engineering, IIT Madras

Metallic glasses (MGs) are potential structural and functional materials on account of their

disordered configuration of atoms. Since the discovery of glass formation in metallic system

in 1960s, a lot of research in this field culminated into discovery of glass forming alloys that

contain elements spanning the entire periodic table. However only certain alloy compositions

are known to be good glass formers that can be easily processed and find industrial applications.

To augment the industrial applicability of MGs, there exists a need to develop MGs that can be

processed through conventional casting techniques and form glass phase in bulk form. In order

to meet this challenge of novel glassy alloy development, new perspectives of composition

design for BMGs need to be explored. Designing MGs through high entropy alloy (HEA)

philosophy is a promising pathway that can radically cut down alloy development time and

also might result in MGs with excellent glass forming ability. However, given the number of

permutations possible for HEAs to be the order of astronomical number proportions by just

considering the conventional metallic elements; there exists a need to find an innovative

thermodynamic basis for predicting glass formation apriori. In this paper, PHSS parameter which

is developed on the basis of Inoue’s criteria for MG formation is used to distinctly categorize

solid solution forming HEAs from MG forming alloys. The efficacy of this parameter is

demonstrated for various alloy systems to predict novel MG forming compositions in high

entropy regime. To conclude, the capability of the PHSS model and the scope for further research

in this direction are discussed.

32

Poster Presentation Abstracts

33

Microstructural Characterization of Plasma Sprayed High Entropy Alloy

Coatings

Ameey Anupam1, S. Praveen1, A.S.M. Ang2, M.L. Sesso, R.S. Kottada1, B.S. Murty1 and

C.C. Berndt2,3 1 Indian Institute of Technology Madras, Chennai, India

2 Swinburne University of Technology, Melbourne, Australia 3 Stony Brook University, Stony Brook, USA

Five-component High Entropy Alloy (HEA) AlCoCrFeNi powders were prepared by 10 hours

of Mechanical Alloying (MA), and subsequenlty coated on mild steel substrate via

Atmospheric Plasma Spraying (APS). XRD of the MA powder showed predominantly BCC

phase with minor FCC phases. These phases transformed to major FCC and minor BCC phases

together with oxides upon coating. The coating microstructure studied by XRD, SEM, EPMA

and TEM shows formation of 4-component NiCoCrFe-HEA, NiCo phases along with alumina,

Al-Cr rich oxides, and mixed oxides. Al, Cr and Fe get preferentially oxidized upon exposure

to plasma temperatures of >10,000 K forming various oxides, while NiCoCrFe and NiCo are

retained inside the particle. This corroborates transformation of Al-stabilized BCC phase in

powders to Al-depleted FCC phase in the coating. This work is geared towards exploring the

use of HEA coatings as potential substitutes for current bond coats (MCrAlY, M - Ni, Co) in

Thermal Barrier Coating (TBC) systems.

34

Phase Evolution, Densification, and Compressive Properties of High

Entropy Alloys

S. Praveen*, B.S. Murty and Ravi Sankar Kottada

Indian Institute of Technology Madras, Chennai

High Entropy alloys that are made up of multi-component (more than four) elements mixed in

equi-atomic proportions, have shown extraordinary properties such as strength retention and

stability of microstructure at high homologous temperatures. In the present study, mechanical

alloying and spark plasma sintering was chosen as a processing route to synthesize dense

pellets of various compositions comprising of Al, Co, Cr, Cu, Fe, and Ni. Each of these

individual elements has their significant influence on phase evolution and densification. For

example, Ni containing alloys tend to form a FCC phase whereas Al containing alloys tend to

form a BCC phase, immiscible nature of Cu with most of the elements makes Cu to segregate

as a Cu rich FCC phase. Similarly, Cr containing alloys get densified better than other alloys.

From the phase evolution and densification studies, CoCrFeNi was chosen as a promising

candidate for thermal stability studies, compression testing at room temperature and high

temperature, and compression creep. The dense CoCrFeNi alloy did exhibit excellent thermal

stability even after annealing at 700oC for 600h by retaining its microstructure, grain size, and

hardness. XRD, SEM, TEM and 3DAP characterisation techniques have been utilized at

different stages starting from mechanical alloying till mechanical property studies to

understand the phase evolution, densification behaviour, and compressive properties.

35

Alloying and Phase Evolution in Refractory CrMoNbTiW High Entropy

Alloy

Lavanya.R1, Ravi Sankar Kottada1, B.S. Murty1 and S.V.S. Narayana Murty2

1Department of Metallurgical and Materials Engineering,

Indian Institute of Technology Madras, Chennai 600036 2Advanced Metallography Section, Vikram Sarabhai Space Centre, ISRO, Trivandrum,

695022

Ever since the advent of high entropy alloys (HEAs) in 2004, most of the work on these alloys

is focused on involving transition metals such as Fe, Co, Ni and other elements in this series.

Recently, the same concept of high entropy emerging from equi-atomic compositions has been

extended to elements whose melting point is in the range of 1500 – 3000 C. These alloys are

termed as refractory high entropy alloys (R-HEA).

In the present study, primary focus is on understanding the phase evolution in CrMoNbTiW R-

HEA. Mechanical alloying of the elemental powders of this alloy resulted in formation of a

single BCC phase. Mechanically alloyed powders were sintered in commercial spark plasma

sintering to obtain dense pellets. XRD, SEM and TEM were extensively utilized to do detailed

microstructural characterization of the powders and sintered pellets. Hardness measurements

and preliminary compression tests were carried out on the sintered pellets. Phase evolution and

preliminary mechanical properties are compared with R-HEAs obtained through casting route.

36

Design of High Entropy Metallic glass Compositions from Invariant

Reactions Predicted by CALPHAD Methods through PHSS Parameter

K.S.N. Satish Idury1, B.S. Murty2 and Jatin Bhatt1* 1Department of Metallurgical and Materials Engineering, V.N.I.T Nagpur

2Department of Metallurgical and Materials Engineering, IIT Madras

High Entropy alloys (HEAs) currently garner huge interest in materials research domain in

view of their exceptional properties [1]. The greatest advantage that can be derived from

designing metallic alloys through this perspective is the simplification of alloy design in

addition to realization of four core effects (high entropy effect, sluggish diffusion, lattice

distortion and cocktail effect) inherent to alloys with equi/near equi atomic concentrations [2].

Simplification of alloy design can be of great boon to metallic glass (MG) research community

to explore glass formation in highly untapped regions in compositional space of multi

component alloys. Currently, capturing the window of mixing enthalpy (∆Hmix) and topological

strain (δ parameter, ΔSσ /kB) of alloys in high entropy regime is the popular method to

distinguish between MG forming and solid solution forming HEAs [3, 4].

However, while predicting MG formation through the optimized window of thermodynamic

and topological parameters, caution need to be exercised. This work emphasizes that careful

consideration of glass formation in the sub binary, ternary and quaternary systems of a multi

component alloy can provide a reliable guideline to design high entropy MG formers. This fact

is demonstrated by substituting Be Hf and Al to quaternary eutectic regions of Zr-Ti-Cu-Ni

alloys and evaluating their propensity for glass formation at equi atomic concentrations. By

analyzing their thermodynamic driving force through novel PHSS parameter [5] which is

designed based on Inoue’s criteria for glass formation, these alloy systems are ranked based on

PHSS parametric ranges. Zr-Ti-Cu-Ni-Be system is demonstrated to be the alloy system with

excellent glass forming ability (GFA) in comparison to Zr-Ti-Cu-Ni-Al and Zr-Ti-Cu-Ni-Hf.

The origin of excellent GFA for Zr-Ti-Cu-Ni-Be system is attributed to ternary equi atomic Zr-

Ti-Be [6] alloy which enables glass formation in multitude of higher order alloy systems. It is

opined that though many deep eutectic regions exist in higher order alloy systems, only certain

compositional regions among these deep eutectics have superior GFA and enable optimum

glass formation in high entropy regimes. This work proves that phase stability data of ternary

phase diagrams is of immense help to predict GFA in high entropy alloys. To conclude, this

work also advocates that more work need to be undertaken to assess whether invariant reactions

predicted for multi component alloys through CALPHAD methods can provide positive

direction to the development of high entropy metallic glasses.

References: 1. B.S. Murty, J.W. Yeh, S. Ranganathan, High Entropy Alloys, BH, 2014

2. Y. Zhang, T.T. Zuo, Zhi Tang, M.C. Gao, K.A. Dahmen, P.K. Liaw, Z.P. Lu, Progress in

Materials Science, 61 (2014), pp.1-93

3. S. Guo, Q.Hu, Chun Ng, C.T. Liu, Intermetallics 41 (2013), pp.96-103

4. A. Takeuchi, K. Amiya, T. Wada, K. Yubuta, W. Zhang, A. Makino, Mater. Trans. 55

(2014) pp. 165-170

5. B.R. Rao, M.Srinivas, A.K. Shah, A.S. Gandhi, B.S. Murty, Intermetallics, 35 (2013), pp.

73-81

6. A. Wiest, G. Duan, M.D. Demetriou, L.A. Wiest, A. Peck, G. Kaltenboeck, B. Wiest, W.L.

Johnson, Acta Mater 56 (2008), pp.2625-2630

37

Carbide Formation during Synthesis of Co-Cu-Fe-Mn-Ni -W

Multicomponent Alloys by Mechanical Alloying and

Spark plasma Sintering Route

Anoop K., Pramod S.L. and Srinivasa R, Bakshi

Department of Metallurgical and Materials Engineering,

Indian Institute of Technology Madras, Chennai 600036

High entropy alloys (HEA) having four or more elements in equi-atomic proportions and

having simple crystal structures are attracting researchers due to their promising properties like

high temperature stability and good mechanical properties. In the present study, the alloys

FeCoMnW, FeCoMnCuW, FeCoMnNiW and FeCoMnNiCuW were synthesized by high

energy ball milling of elemental powders followed by Spark Plasma Sintering (SPS). The

compositions were selected to produce promising tool materials. XRD analysis of the 20 hr

milled powders indicated formation of two phases (1BCC and 1FCC) and WC contamination

in the powders. SEM EDS showed excellent homogeneity of the composition in the powders.

XRD analysis of the sintered samples showed presence of WC and (Fe,Mn)3W3C and peaks

corresponding to the matrix. SEM analysis showed presence of blocky carbide particles in

multi-component matrix. CHN analysis of milled powder showed about 2 wt.% carbon in the

milled powders which was formed due to dissociation of Toluene. The carbon was found to

be sufficient to generate high amount of carbides in the sintered samples. The carbide

morphology changed with composition. Hardness of samples was studies.

38

Synthesis and Characterization of FeAlZnCrCuMgSi and

FeAlZnCrCuMgMn High Entropy Alloys by Mechanical Alloying

Nandini Singh* and N.K. Mukhopadhyay

Department of Metallurgical Engineering, IIT BHU, Varanasi-221005

Traditional trend has been to design alloy by taking one base metal with minor addition

of other constituent elements. Incorporation of more multiprincipal elements often leads

to the formation of intermetallics or other complex structures which are brittle and difficult

to process. However this paradigm of design has been proved to be false with the advent

of High entropy alloys(HEAs). HEAs being defined as Multi-component alloys containing

atleast five principal elements with concentration between 5at% and 35at% are potential

applicants for high temperature structural materials and bear improved hardness, oxidation

resistance and corrosion resistance. In present work FeAlZnCrCuMgSi and

FeAlZnCrCuMgMn HEAs were synthesized by Mechanical alloying for 50hrs using

PM400(Restch®). Purpose of present work was to study the effect of addition of

metalloid Si with DC structure and Mn metal with almost same size and electronegativity

to earlier synthesized FeAlZnCrCuMg HEA. Phase was determined by XRD and TEM.

Both the alloys consist of single solid solution BCC phase. Crystallite size and lattice strain as

determined after 50 hrs of milling for FeAlZnCrCuMgSi alloy were 38nm and 0.66%

respectively. For same duration of milling for FeAlZnCrCuMgMn alloy, crystallite size and

lattice strain were 51nm and 0.71% respectively. SEM was used for compositional analysis and

powder size determination at different times of milling. Hardness of sintered powder alloys

FeAlZnCrCuMgSi and FeAlZnCrCuMgMn obtained after 50hrs milling came out to be 623HV

and 426HV respectively. Efforts will be made to understand the structural evolution, stability

and the mechanical properties of the milled HEAs.

39

Synthesis and Characterization of Fe-Al-Zn-Cr-Cu-Mg and Fe-Al-Zn-Cr-

Cu-Mg-Co High Entropy Alloys by High Energy Ball Milling

Vikas Shivam*, Santhosh K. Alla, R.K Mandal and N.K. Mukhopadhyay

Department of Metallurgical Engineering,

Indian Institute of Technology (BHU), Varanasi-221005

The design of conventional multicomponent alloy systems includes one major element along

with the additions other elements and seldom has it required more than three principal metallic

elements. Generally, this type of multicomponent alloys always display formation of solid

solution along with intermetallic compounds and complex microstructural forms. But, high

entropy alloys (HEAs) are the multicomponent alloys having at least five principal metallic

elements without the formation of intermetallic compounds. These HEAs possess excellent

properties like higher hardness, strength as well as improved wear, oxidation, good corrosion

resistance and other functional properties. The purpose of present work is to design and

develop new high entropy alloy avoiding HCP structure. With this consideration, Fe-Al-Zn-

Cr-Cu-Mg and Fe-Al-Zn-Cr-Cu-Mg-Co high entropy alloys were selected for mechanical

alloying. Alloys were synthesized by high energy ball milling using P-5 Planetary ball mill

PM400 (Retch) up to 45 hours. Structural characterization has been carried out by X-ray

diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy

(TEM). In both the cases, body-centered cubic (bcc) structure with lattice parameter of 2.88 Å

was observed. Microhardness of FeAlZnCrCuMg high entropy alloy sintered at 900 °C was

910 HV. All FeAl, FeAlZn, FeAlZnCr, FeAlZnCrCu, FeAlZnCrCuMg five systems are

forming BCC structure and FeAlZnCrCuMgCo also forming nearly single phase BCC

structure. It should be noted that, all systems are having BCC structure elements like Fe and

Cr are stronger elements which are more open structure with high melting point. This may be

the reason that formation of BCC structure in these systems. Finally, even though, constituents

of two alloys are having different crystal structure and large difference in the atomic radii,

showing formation of single phase. Attempts will be made to discuss the results on the

structure and stability of the phases during milling.

40

An ICME approach for Development of Ductile Single Phase High Entropy

Alloy

Tazuddin, N. P. Gurao, Krishanu Biswas*

Department of Materials Science and Engineering, Indian Institute of Technology Kanpur

Kanpur-208016

High Entropy Alloy (HEA) is a new class of material with tunable properties that have excellent

potential to be used in high temperature, aerospace, automotive and biomedical applications.

The HEAs derive their exceptional properties like excellent strength, oxidation resistance, wear

and corrosion resistance due to their higher configurational entropy (≥1.61R) compared to

conventional multi element alloys. These properties along with ductility are expected to be

enhanced in single phase high entropy alloys. However, till date only few single phase HEAs

with five or more elements have been found and only one study on secondary processing of

these alloys by cold rolling has been reported. Integrated computational materials engineering

(ICME) approach is very effective in terms of cost and time to develop and optimize new

alloys. In the present investigation, we apply CALPHAD (CALculation of PHAse Diagrams)

approach to unearth a single phase FCC HEA composition of equiatomic MnCuCoFeNi HEA.

The cast alloy after homogenization could be subjected to cold rolling to 90% thickness

reduction and showed a single component Brass {110}<1-12> texture which is characteristic

of low stacking fault energy FCC material. There was an increase in hardness with rolling and

the hardness more than doubled after 90% rolling reduction (163±8.5 to 399±5.96 VHN) like

conventional FCC materials deforming by dislocation activity. The formation of characteristic

Brass component can be attributed to extensive planar slip in the low SFE HEA. The

deformation texture remained unaltered with decrease in hardness (399±5.96 to 191±2.61

VHN) after annealing to temperature as high as 900 °C (0.75 Tm) for one hour. It is expected

that ductile MnCuCoFeNi HEA can have excellent creep and oxidation resistance and can be

used for engineering applications at high temperature.

41

Phase Separation in Mechanically Alloyed High Entropy Alloys (HEAs)

Taraknath Maity, Sutanuka Mohanty and Krishanu Biswas

Department of Materials Science and Engineering,

Indian Institute of Technology Kanpur 208016

The multi-component high entropy alloys (HEAs) are defined as solid solution alloys

containing equal to or more than five principal elements in equal or near equal atomic

percentage [1]. In the earlier investigation, it has been explored that multi principal elements

in alloys leads to the formation of intermetallic phases, complex microstructure and poor

mechanical properties. However, the HEAs are found to be consisting of FCC and/or BCC

phases and HCP phase [2]. Therefore these alloys are drawing the attention in both

scientific and technological community as they exhibit interesting fundamental physics and

technological promises [2]. In the literature, most of the HEAs are reported to be multi-

phase rather than single-phase solid solutions. Phase separations have been observed in

HEAs e.g. in AlCoNiCuZn [2], AlCoCrFeNi [3]. The microstructure of as cast AlCoCrFeNi

HEAs shows clearly distinguishable dendrites and interdendrites that has been investigated

using transmission electron microscopy and atom probe tomography indicating the

formation of Cr-Fe rich precipitate into Al-Ni rich matrix. AlCoNiCuZn HEA revealed the

formation of ordered LI2 structure within the grains of FCC HEA [2].

The present investigation is, therefore, focused on the phase separation in equiatomic

multi component TiFeNiCoCu and AlCoCrFeNi HEAs, prepared by mechanical alloying

under protective argon atmosphere followed by consolidation using spark plasma sintering

(SPS) at different sintering temperatures. Both the as milled powder and sintered specimens

are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM)

for phase identification. The detailed XRD of TiFeNiCoCu HEA (fig.1a) indicate the

presence of a single phase , FCC (α) solid solution in 15 hours ball milled powder and after

consolidation of the powder using SPS at different temperatures indicate the presence of one

major FCC1 (β) phase and another minor FCC2 (γ) phase. SEM micrograph of sintered

sample shows spinodally decomposed microstructure consisting of FCC (Cu)SS and FCC

(Co)SS phases. The detailed XRD of AlCoCrFeNi HEA (fig.1b) indicates the presence of a

single phase, FCC (γ) solid solution in the 25 hours ball milled powder. However the sintering

of the as-milled powder at 900 ºC and 1000 ºC revealed the formation of σ (Fe-Cr) phase in an

Al-Ni rich matrix with ordered FCC (LI2) structure. The hardness studies show significant

increase from 1.54 to 8.1 GPa as the sintering temperature increases from 800 ºC to 1000 ºC

because of the formation of σ (Fe-Cr) phase.

42

Fig.1a X-ray diffraction patterns of TiFeCoNiCu HEAs pellets sintered at different sintering

temperatures. The pattern at the bottom is from 15 hours ball milled sample.

Fig.1b X-ray diffraction patterns of AlCoCrFeNi HEAs pellets sintered at different sintering

temperatures. The pattern at the bottom is from 25 hours ball milled powder

References:

1. Yong Zhang, Ting Ting Zuo, Zhi Tang, Michael C. Gao, Karin A. Dahmen, Peter K. Liaw,

Zhao Ping Lu, Prog. Mater. Sci. 61 (2014) 1–93

2. Sutanuka Mohanty, N.P Gurao, Krishanu Biswas, Mater. Sci. Eng..A, 617 (2014) 211-218

3. A. Manzoni, H. Daoud, R. Volkl, U. Glatzel, N. Wanderka, Ultramicroscopy 132 (2013)

212–215.

43

Powder Metallurgy of High Entropy Alloys

Rahul Mane, Ashif Equbal, Y. Rajkumar, Bharat B. Panigrahi*

Department of Materials Science and Metallurgical Engineering

Indian Institute of Technology Hyderabad, Yeddumailaram, 502205

High entropy alloys are relatively new class of alloy, having minimum five principal

components with high configurational entropy. The mixing of the elements are done usually in

equiatomic ratio. However, some non-equiatomic elements in small fractions may be added to

alter the properties of the alloy. These alloys exhibit unique combination of properties such as,

high strength combined with relatively high ductility, high oxidation and corrosion resistance,

etc. This material has potential to replace many of the existing super-alloys and high

temperature materials in various engineering and strategic applications. Induction melting or

arc-melting and castings have been the conventional route to produce bulk material. Since

manufacturing through powder metallurgy (PM) has several advantages for many applications;

it is the need of the hour to investigate the potential of these alloys for PM processing route.

So far, the mechanical alloying of elemental powders has been there for producing high entropy

alloy powders. However, there have been many issues in mechanical alloying route and

subsequent sintering stages; which need to be understood. Some of the objectives of the present

study are: synthesis and optimization of alloying conditions, study the sintering bahviour and

their phase evolution during sintering. Initially the work was started with the preparation of

FeCrCoMnNi alloy and has been extended to the other alloys systems. A planetary ball mill

with tungsten carbide milling system has been used in this study to synthesise the powder.

Sintering studies have been carried out in under inert atmosphere and vacuum.

44

Effect of Starting Grain size on Thermos-Mechanical Processing Response

of CoCrFeMnNi High Entropy Alloy

G.D. Sathiaraj, P.P. Bhattacharjee*

Department of Materials Science and Metallurgical Engineering

Indian Institute of Technology Hyderabad

Ordnance Factory Estate, Yeddumailaram, 502205

The effect of initial grain size on the formation of microstructure and texture in heavily

cold rolled equiatomic CoCrFeMnNi high entropy alloy (HEA) was investigated. For

this purpose two alloys with average grain size ̴7 µm (fine grained starting material or FGSM)

and 200 µm (coarse grained starting material or CGSM) were cold-rolled to 95% reduction in

thickness and isochronally annealed for one hour over a wide temperature range. The

FGSM showed finer grain size as compared to CGSM after annealing at high temperatures. In

contrast, the starting grain sizes did not show any pronounced effect on texture formation. The

mechanism of texture evolution could be explained based on the absence of preferential

nucleation and growth in the experimental HEA.

45

Microstructure and Texture Evolution during Hot Deformation of

Equiatomic High Entropy CoCrFeMnNi Alloy

E.R. Reddy, P.P. Bhattacharjee*

Department of Materials and Metallurgical Engineering

Indian Institute of Technology Hyderabad

ODF Estate, Yeddumailaram 502205

High Entropy Alloys (HEAs) are multicomponent equiatomic or near equiatomic alloys which

exhibit many novel properties. The present work attempts to investigate the evolution of

microstructure and texture during hot deformation of CoCrFeMnNi alloy. Hot deformation

of this material is carried out to 60% reduction by uniaxial compression over a wide

range of temperature (700°C-1000°C) and strain rate (0.001/s-1/s). The evolution of

microstructure and texture are investigated using Electron Backscatter Diffraction (EBSD).

The present results show that hot deformation can lead to the formation of near ultrafine

microstructure and characteristic texture in HEAs.

46

Understanding Structural Evolution and Associated Mechanical Behaviour

in a Nanocrystalline AlCrCuCoFeNi High Entropy Alloy System

G. Ramya Sree1, Ravi C. Gundakaram2 and Koteswararao V. Rajulapati1* 1School of Engineering Sciences and Technology

University of Hyderabad, Hyderabad 500046 2International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI),

Hyderabad 500005.

Nanocrystalline AlCrCuCoFeNi High Entropy Alloy (HEA) was synthesized by mechanical

alloying of Al, Cu, Cr, Co, Fe and Ni elemental powders in equal atomic ratios for 60 hours

where the ball to powder weight ratio was 5:1. Alloy after milling period showed a plate like

structure with thickness of about 1 µm. Structural characterization was done using XRD, SEM

and TEM. The crystallite size gradually decreased and reached a saturated size of 9 nm with

milling time (measured using TEM analysis). As the milling time increased all the elemental

peaks disappeared and formed a single solid solution with FCC crystal structure. Spark Plasma

Sintering (SPS) is being used to make bulk components out of the milled powders. Mechanical

behavior has been investigated using microindentation and nanoindentation. In the end

structure-property correlations will be discussed and challenges will be outlined.

47

Synthesis and Mechanical Properties of

Ti-V-Cr-Zn-Nb Multi-Component High Entropy Alloy

Akanksha Dwivedi1, Ravi C. Gundakaram2 and Koteswararao V. Rajulapati1,*

1School of Engineering Sciences and Technology

University of Hyderabad, Hyderabad-500046 2International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI),

Hyderabad 500005

Traditional alloys are based on one or two major principal elements. High entropy alloys are

equiatomic multicomponent alloys, wherein configurational entropy increases and hence single

phase solid solution is obtained. These alloys can be potentially used in different application

that demand high temperature strength, oxidation resistance, corrosion resistance and wear

resistance. The present study describes the synthesis and characterization of a novel

nanocrystalline equiatomic Ti-V-Cr-Zn-Nb high entropy alloy by mechanical alloying and

spark plasma sintering. The prepared high entropy alloy was characterized for its structural,

morphological, compositional and thermal properties by using XRD, SEM, EDS, DSC and

TEM. The effects of milling duration on phase and structure evolution were investigated.

Average crystallite size was measured by TEM. The 60 hours ball milled powder was found to

exhibit the lattice parameter and average crystallite size as 4.203A° and 7.0 nm respectively.

The prepared alloy was observed to be solid solution having FCC crystal structure by XRD.

The obtained powders are consolidated into bulk components using spark plasma sintering and

the mechanical properties are being evaluated using Vickers microindentation and depth

sensing nanoindentation. In the end structure-property correlations will be established in this

novel alloy system.

48

Structural Stability of Nanocrystalline Multi-Component Ti-Ni-Cr-Co-Fe

Alloy

Abhijit1, Muvva D. Prasad2 and Koteswararao V. Rajulapati1*

1 School of Engineering Sciences and Technology,

University of Hyderabad, Hyderabad 500046 2Centre for Nanotechnology, University of Hyderabad, Hyderabad 500046

In the present work, a new HEA system was synthesized, characterized and analyzed. Ti-Ni-

Cr-Co-Fe alloy was prepared from the powders of individual elements in equiatomic ratio

through vacuum arc melting route. As-cast alloy possessed heterogeneous microstructural

details. In order to break this heterogeneity, the sample was subjected to ball milling.

Mechanical alloying of this cast sample was carried out using SPEX 8000D high energy ball

mill and it resulted in homogeneous single solid solution. The milled powder samples were

sintered using spark plasma sintering at 0.5TM and 0.6TM (where TM is the theoretical melting

point of this alloy, 1885.6 K). These sintered samples were then characterized using XRD,

SEM-EDS for compositional analysis and TEM. In this poster, the final structural details will

be presented and stability issues/challenges will be outlined.

49

Effect of Thermo-Mechanical Processing on the Microstructure and

Mechanical Properties of Ti-Al-Ni-Cr-Co based High-Entropy Alloys

Anand Sekhar R1, Niraj Nayan2, G Phanikumar1, Bakshi S R1,

1Department of Metallurgical and Materials Engineering,

Indian Institute of Technology, Madras, Chennai – 600036 2Vikram Sarabhai Space Centre, Thumba, Thiruvananthapuram - 695022

The objective of this work was to synthesize TiAlNiCr and TiAlNiCrCo multicomponent

alloys and study their microstructure and mechanical properties. The alloy powders were

prepared by ball milling of elemental powders and consolidated by Spark Plasma Sintering

(SPS). These alloy compositions show two BCC phases after 8 hours of milling. Thermo-

mechanical processing studies were carried out using Gleeble®3800 to understand the effect

of high temperature deformation on the microstructure and mechanical properties of these

HEAs. Samples were subjected to compression tests at 600, 700, 800, 900 and 1000 °C. Room

temperature compressive test were also conducted on the samples. The phase evolution after

the compression tests were studied using XRD. Microstructural characterization was done

using Optical microscope and SEM. Effect of phase evolution on the mechanical properties

was studied using nano-indentation with a Berkovich indenter. Elastic modulus and hardness

of the phases were measured from load the displacement curves. Results explain the

contribution of each phase on the mechanical property. Microhardness was also measured on

the samples before and after compression.

50

Symmetry Considerations for Computation of Orientational Entropy in

Jahn-Teller active systems

Rameshwari Naorem, Anandh Subramaniam

Materials Science and Engineering,

Indian Institute of Technology Kanpur, Kanpur-208016

In Orientational High Entropy Alloys (OHEA) the entropic benefit more than makes up for the

strain energy cost and stabilizes the disordered phase in preference to an orientationally ordered

compound (of lower symmetry). In one class of OHEA reported, the degeneracy of multiple

orientations of the distorted polyhedron gives rise to the entropy in the disordered state, which

arises due to Jahn-Teller effect. For crystal structures with ocathedrally and tetrahedrally

coordinated metal ions (d-orbital bonding), which display Jahn-Teller distortion, the number

of orientational variants can be computed using crystallographic equivalence. In the current

work the configurational entropy benefit due to the orientational degeneracy is calculated for

systems, wherein Jahn-Teller distortion (due to removal of eg degeneracy for octahedral

coordination and t2 degeneracy for tetrahedral coordination) leads to a lowering of the

symmetry of the coordination polyhedron. A subset of these Jahn-Teller active crystals are

orientational high entropy systems.

Keywords: Orientational High Entropy Alloys, Orientational Disorder, Jahn-Teller Distortion.

51

Phase Prediction in Multi-principal Element Systems through CALPHAD

Method: A case study on Co-Cr-Fe-Ni System

K. Guruvidyathri, B.S. Murty and K.C. Hari Kumar

Department of Metallurgical and Materials Engineering

Indian Institute of Technology Madras, Chennai 600036

The name high entropy alloys was first used about a decade ago [1] for equiatomic/near

equiatomic multicomponent alloys. The high configurational entropy resulting from such

compositions was believed to stabilize simple solid solutions in their microstructure [2,3].

Quantities such as Gibbs energy, enthalpy of mixing, atomic size mismatch, valence electron

concentration, electronegativity difference, etc. are also have been used explain their formation

[4,5]. Moreover, kinetic factors are also expected to play a role in deciding the long-time

stability of these phases at elevated phases.

In order to develop better understanding on phase formation in such alloys, phase prediction

by computational materials thermodynamics has been attempted in this study. CALPHAD

(CALculaion of PHAse Diagram) technique for phase prediction has proven to be successful

in the last few decades [6]. The challenge in applying this technique for equiatomic/ near

equiatomic multicomponent alloys is in developing a database that works for wider range of

compositions [7].

For Co-Cr-Fe-Ni system such a database is made and the vertical sections of phase diagrams

are computed. Experimentally, a single phase FCC solid solution is observed in this system for

equiatomic composition at room temperature [8,9]. Interestingly, the predicted vertical sections

show that single phase FCC is possible only at high temperature range. About 600°C and below

more than one phase is seen. Long term heat treatments for about 15 days at 600°C have been

carried out to see whether it results in more than one phase as predicted by CALPHAD. This

is expected to bring insight into the reason behind the stability of single phase FCC in this

system.

References:

1. J.W. Yeh, S.K. Chen, J.Y. Gan, T.S. Chin, T.T. Shun, C.H. Tsau and S.Y. Chang, Adv. Eng.

Mater., 6 (2004) 299–303.

2. S. Praveen, B.S. Murty and Ravi S. Kottada, Mater. Sci. Eng. A, 534 (2012) 83– 89.

3. F. Otto, Y. Yang, H. Bei and E.P. George Acta Mater., 61 (2013) 2628–2638.

4. Y. Zhang, Y. J. Zhou, J. P. Lin, G. L. Chen and P. K. Liaw, Adv. Eng. Mater., 10 (2008),

534- 538.

5. A. K. Singh and A. Subramaniam, J. Alloys Compd., 587 (2014), 113-119.

6. N. Saunders and A. P. Miodownik, CALPHAD (Calculation of Phase Diagrams): A

Comprehensive Guide, Pergamon (1998).

7. F. Zhang, C. Zhang, S. L. Chen, J. Zhu, W. S. Cao and U. R. Kattner, CALPHAD: Computer

Coupling of Phase Diagrams and Thermochemistry, 45 (2014), 1–10.

8. S. Guo, C. Ng, Z. Wang and C. T. Liu, J. Alloys Compd., 583 (2014), 410-413.

9. A. Durga, K.C. Hari Kumar and B.S. Murty, Trans Ind. Inst. Metals, 65 (2012) 375-380.

52

Amorphisation by destabilisation of binary crystalline intermetallic

compound with equiatomic multicomponent substitution

S. Ranganathana, S. Kashyapa, C. Chattopadhyayb, A. Takeuchic, Y. Yokoyamac, B.S.

Murtyb aDepartment of Materials Engineering, Indian Institute of Science, Bangalore - 560012

bDepartment of Metallurgical and Materials Engineering, Indian Institute of Technology

Madras, Chennai - 600036 cInstitute of Materials Research, Tohoku University, Sendai, Japan

The present work investigates the effects of equiatomic substitution of two or more elements

in place of each element in stable binary intermetallic compounds. Thus, highly stable, binary

intermetallic compounds Ni2Ti (alloy 1), NiTi (alloy 2) and NiTi2 (alloy 3) were chosen and

Ni and Ti were substituted with Ni-Cu and Ti-Zr-Hf, respectively, in equiatomic proportions.

Electric arc furnace melting and thereafter melt spinning were utilised to form amorphous

alloys. The XRD, DSC and TEM studies revealed that the alloys formed complete amorphous

structure. Very interestingly, the crystallisation studies of the three alloys show that alloy 1 and

2 show considerably high temperature of crystallisation (above 750 K) and high activation

energy of crystallisation (435 and 452 kJ/mol for alloy 1 and 386 and 347 kJ/mol for alloy 2),

which invariably indicate that the amorphous structure is highly stable in these alloys.

53

Kinetic Model for Prediction of Phase Formation in High Entropy Alloys

C. Chattopadhyay and B.S. Murty*

Department of Metallurgical and Materials Engineering

Indian Institute of Technology Madras, Chennai -600036, India.

A completely predictive theoretical model has been proposed which is principally based on

kinetic parameter, viscosity, along with several thermodynamic and structural properties of the

final alloy based on the constituting elements. In order to predict the phase formation among

amorphous, BCC, FCC or HCP phases, TTT diagrams of four experimentally examined alloys,

ZrTiCuNiBe, AlCoCrFeNi, CoCrFeMnNi and AlCuMgMnZn, were generated with the help of

the viscosity data. The prediction of amorphous, BCC and FCC phase in these alloys matches

excellently with the experimental findings. The present approach acts as an efficient guide for

the cooling rate that should be adopted for obtaining a particular phase in a given

multicomponent equiatomic elemental combination, via the critical cooling rate Rc obtained

through the predicted TTT diagrams.

54

Microstructural and mechanical behaviour of

2024 aluminium - high entropy alloy composites

K Praveen Kumar1 M Gopi Krishna2 J Babu Rao3 NRMR Bhargava3

1Dept. of Mechanical Engineering, R.V.R. & J.C. College of Engineering, Guntur-522019 2Dept. of Mechanical Engineering, ANU College of Engineering &Technology, Guntur-

522510 3Dept. of Metallurgical Engineering, College of Engg., Andhra University, Visakhapatnam-

530003

Work has been carried out to produce composites with high strength and good ductility by

maximizing a uniform and smooth interface for effective transfer of load and minimizing

reinforcement agglomerations / cracking / pull outs. High strength, high entropy alloy (ternary)

in particulate (HEAp) form was used as reinforcement in 2024 aluminium. AA 2024-HEAp

composite was prepared through stir cast route by dispersing an average particle size of 125

μm as reinforcement with various weight fractions varying between 5 and 15%. Subsequently,

billets were hot extruded to 14 mm Ø rods. All the extrudates were thoroughly homogenized

with industrial furnace at 1000C for 24 hours. The mechanical behaviour of alloy and

composites was studied in terms of resistivity, hardness, and tensile studies. An increment of

62% in hardness has been observed. Increased reinforcement contents enhance the mechanical

properties such as yield strength, tensile strength and Young’s modulus.

Keywords: Metal Matrix Composites, Stir-casting, Composite Metallic Materials, High

Entropy alloy.

55

List of Participants for the Workshop

S.No Name Institute E-mail ID

1. JW Yeh

National Tsing Hua

University, Taiwan

jwyeh@mx.nthu.edu.tw

2. D Miracle US Air Force Base, USA daniel.miracle@us.af.mil

3. Rajiv Mishra University of North

Texas, USA

Rajiv.Mishra@unt.edu

4. Chris Berndt

Swinburne University,

Australia

cberndt@swin.edu.au

5. James D Cotton Boeing Research &

Technology, USA

james.d.cotton@boeing.com

6. John Lembo Boeing Research &

Technology, USA

John.r.lembo@boeing.com

7. Natalia

Mitropolskaya

Boeing research &

Technology, Russia

Natalia.m.mitropolskaya@boein

g.com

8. Mahender Reddy Boeing Research &

Technology, USA

Mahender.c.reddy@boeing.com

9. Sera Wang Boeing Research &

Technology, USA

Seraphine.n.wang@boeing.com

10. KG Pradeep RWTH Aachen,

Germany

kgprad@gmail.com

11. R Krishnan Bangalore rangachari.krishnan@gmail.com

12. Umesh Waghmare JNCASR, Bangalore waghmare@jncasr.ac.in

13. Meha Bhogra JNCASR, Bangalore megabhogra@gmail.com

14. S Ranganathan IISc Bangalore rangu2001@yahoo.com

15. K Chattopadhyay IISc Bangalore kamanio@materials.iisc.ernet.in

16. AH Chokshi IISc Bangalore achokshi@materials.iisc.ernet.in

17. Abhik Chowdhury IISc Bangalore abhiknc@materials.iisc.ernet.in

18. Vijay Sethuraman IISc Bangalore vijay@materials.iisc.ernet.in

19. Sanjay Kasyap IISc Bangalore kashyapsanjay@gmail.com

20. M Surendra Kumar IISc Bangalore surendra.makineni@gmail.com

21. Shalini Roy IISc Bangalore koneru.shaliniroy@gmail.com

22. Praful Pandey IISc Bangalore prafull1011@gmail.com

23. VS Raja IIT Bombay vsraja@iitb.ac.in

24. Prita Pant IIT Bombay pritapant@iitb.ac.in

25. Gururajan IIT Bombay guru.mp@iitb.ac.in

26. Pinaki Bhattacharjee IIT Hyderabad pinakib@iith.ac.in

27. BB Panigrahi IIT Hyderabad bharat@iith.ac.in

28. Saswata

Bhattacharya

IIT Hyderabad saswata@iith.ac.in

29. Rahul Mane IIT Hyderabad ms14resch11004@iith.ac.in

30. GD Sathiaraj IIT Hyderabad ms12p0003@iith.ac.in

31. E Rajeshwar Reddy IIT Hyderabad ms13m1005@iith.ac.in

32. Y Rajkumar IIT Hyderabad ms12p1005@iith.ac.in

33. K Biswas IIT Kanpur kbiswas@iitk.ac.in

34. Anand Subramanian IIT Kanpur anandh@iitk.ac.in

35. Nilesh Gurao IIT Kanpur npgurao@iitk.ac.in

56

36. Kaustubh Kulkarni IIT Kanpur kkaustub@iitk.ac.in

37. K Mondal IIT Kanpur kallol@iitk.ac.in

38. Tazuddin IIT Kanpur tazuddin@iitk.ac.in

39. Tarak Nath Maity IIT Kanpur maity@iitk.ac.in

40. Rameshwari

Naorem

IIT Kanpur naorem@iitk.ac.in

41. Surekha Yadav IIT Kanpur surekhay@iitk.ac.in

42. Rahul Mitra IIT Kharagpur rahul@metal.iitkgp.ernet.in

43. BS Murty IIT Madras murty@gmail.com

44. KC Harikumar IIT Madras kchkumar@iitm.ac.in

45. Srinivas Rao Bakshi IIT Madras sbakshi@iitm.ac.in

46. Ravi Sankar Kottada IIT Madras ravi.sankar@iitm.ac.in

47. G Phanikumar IIT Madras gphani@iitm.ac.in

48. VS Sarma IIT Madras vsarma@iitm.ac.in

49. Anand Kanjarla IIT Madras kanjarla@iitm.ac.in

50. Uday Chakkingal IIT Madras udaychak@iitm.ac.in

51. V Srinivas IIT Madras veeturi@iitm.ac.in

52. S Varalakshmi IIT Madras varasun@gmail.com

53. Chinmoy

Chattopadhyay

IIT Madras techchinmoy@gmail.com

54. S Praveen IIT Madras spravin88@gmail.com

55. K Guruvidyathri IIT Madras guruvidyathri@gmail.com

56. Ameey Anupam IIT Madras ameeyanupam@gmail.com

57. R Lavanya IIT Madras lavanya.metly@gmail.com

58. Anoop K IIT Madras anoopk23290@gmail.com

59. Anand Shekar R IIT Madras anandskhr@gmail.com

60. Adil Shaik IIT Madras adilmmt01@gmail.com

61. Raghavendra

Kulkarni

IIT Madras rkphy2009@yahoo.com

62. R Anil Prasad IIT Madras anil007prasad@gmail.com

63. NK Mukhopadhyay IIT BHU, Varanasi mukho.met@iitbhu.ac.in

64. Nandhini Singh IIT BHU, Varanasi nandini.singh.met11@itbhu.ac.in

65. Vikas Shivam IIT BHU, Varanasi vikasmit24@gmail.com

66. K Siva Prasad NIT Trichy ksp@nitt.edu

67. Kumaran NIT Trichy kumara@nitt.edu

68. Vinod Kumar MNIT Jaipur vkt.mnit@gmail.com

69. Ornov Maulik MNIT Jaipur maulikornov@gmail.com

70. Jatin Bhatt VNIT Nagpur jatinbhatt@mme.vnit.ac.in

71. Satish Idury VNIT Nagpur satishidury@gmail.com

72. R Koteswara Rao University of Hyderabad kvrse@uohyd.ernet.in

73. G Ramya Sree University of Hyderabad ramyasree2626@gmail.com

74. Akanksha Dwivedi University of Hyderabad akanksha.msme@gmail.com

75. Abhijit University of Hyderabad abhijit18061991@gmail.com

76. J Babu Rao Andhra Univ., Vizag brjinugu@gmail.com

77. KR Ravi PSG Tech krravi.psgias@gmail.com

78. J Nagalakshmi RGUKT, Basara lakshmi.mme@gmail.com

79. Mohan Murali

Krishna

RGUKT, Nuzvid mohanmuralikrishna9@gmail.co

m

57

80. K Praveen Kumar R.V.R & J.C College of

Engg. Guntur

kpraveen717@yahoo.com

81. S Kumar ARCI, Hyderabad skumar@arci.res.in

82. Amit Srivastava BARC, Mumbai apsrivas@gmail.com

83. Sankara

Subramanian

DMRL, Hyderabad sankara@dmrl.drdo.in

84. Bhaskar Majumdar DMRL, Hyderabad bhaskarmajumdar1@gmail.com

85. R Ramakrishnan DMRL, Hyderabad rraghavan@dmrl.drdo.in

86. Joysurya Basu IGCAR, Kalpakkam jbasu@igcar.gov.in

87. S Abhaya IGCAR Kalpakkam sab@igcar.gov.in

88. Jayaraj IGCAR Kalpakkam jraj@igcar.gov.in

89. M Vijayalakshmi IGCAR, Kalpakkam mvl@igcar.gov.in

90. S Raju IGCAR, Kalpakkam sraju@igcar.gov.in

91. A Sasikumaran IGCAR Kalpakkam saikumaran@igcar.gov.in

92. Chiranjit Poddar IGCAR Kalpakkam poddaraditya12@gmail.com

93. R Mythili IGCAR Kalpakkam rm@igcar.gov.in

94. Alphy George IGCAR Kalpakkam alphy@igcar.gov.in

95. Chanchal Gosh IGCAR Kalpakkam chanchal@igcar.gov.in

96. Raj

Narayan Hajra

IGCAR Kalpakkam rnhajra@igcar.gov.in

97. K Sridhar NMRL, Ambarnath sridsudi@gmail.com

98. S Gowtam NMRL, Ambarnath satyag@nmrl.drdo.in

99. Vivek Srivastava NMRL, Ambarnath viveks@nmrl.drdo.in

100. Somnath

Bhattacharya

TIFR, Mumbai somnath@tifr.res.in

101. Amit Salvi TRDDC, Pune salvi.amit@tcs.com

102. Govind VSSC, Trivandrum govind@vssc.gov.in

103. Bala K Bharadvaj Boeing India, Bangalore bala.k.bharadvaj@boeing.com

104. Om Prakash Boeing India, Bangalore Om.Prakash2@boeing.com

105. K Anand GE, Bangalore k.anand@ge.com

106. Sanjay Vaidya Hysitron, Bangalore sanjay@hysitron.com

107. Hemant Gourkar Anton Par hemant.gourkar@anton-

paar.com

108. Verghese Mammen Anton Par verghese.mammen@anton-

paar.com

58

Organising Committee

Chairman Prof M Kamaraj

Convener Prof BS Murty

Co-Convener Dr Ravi Sankar Kottada

Members Prof KC Hari Kumar

Dr Srinivasa Rao Bakshi

Dr Chinmoy Chattopadhyay

Mr Guruvidyarthi

Ms Ameey Anupam

Ms R Lavanya

Mr Adil Shaik

Mr Anil Prasad

Mr K Anoop

Mr R Anand Shekar