evaluation of mechanical properties and ...joics.org/gallery/ics-1175.pdfmicrostructural study of...

EVALUATION OF MECHANICAL PROPERTIES AND

MICROSTRUCTURAL STUDY OF ALUMINUM ALLOY 2014

REINFORCED WITH FLY ASH METAL MATRIX COMPOSITE

Sangadi BhyravaSwamy1*

Gurram Vijay Teja2

1* M.Tech Scholar, 2 Asst. Prof.

Department of Mechanical Engineering,

Kakinada Institute of Engineering and Technology, Kakinada, Andhra Pradesh, India

Email: [email protected]

ABSTRACT

Metal matrix composites (MMC) posses significantly improved properties

such as high specific strength, specific modulus, damping capacity and good wear resistance

compared to un-Reinforced alloys. There has been increasing interests in composites

containing low density and low cost reinforcement. However it is extremely difficult to

obtain uniform dispersion of the nano sized particles in liquid metals due to high viscosity,

poor wet ability and a large surface to volume ratio in the metal matrix. In this context it is

found from the literature that high intensity ultrasonic waves are useful to have uniform

dispersion in the liquid phase as they generate the essential non linear effects required. The

present work deals with the fabrication of the Aluminum matrix nano composites by

ultrasonic dispersion of nano sized Fly Ash particles in molten Aluminum alloy. AA2014 has

been selected as matrix alloy as it is readily castable. The mechanical properties such as

hardness, Young’s modulus, tensile strength will be studied and compared with those of the

base alloy. The correlation of the properties with respect to the variation of the processing

parameters, viz., weight percentage and particle size will be done. The weight percentage of

nano-sized Fly Ash will be varied from 0 to 20% in the step size of 5 while the average size

of the particle will be taken at 0.5µm-300µm. The proposed values are chosen based on the

literature data. In addition, the analysis of the micro-structural properties of metallurgical

structure and grain size were also be carried.

KEYWORDS: Aluminum matrix Nano- Composites, ultra-sonic dispersion, Fly Ash

reinforcement, Stir casting.

Journal of Information and Computational Science

Volume 9 Issue 7 - 2019

ISSN: 1548-7741

www.joics.org143

mailto:[email protected]

1. INTRODUCTION

Conventional monolithic materials have limitations in achieving good combination of

strength, stiffness, toughness and density. To overcome these shortcomings and to meet the

ever increasing demand of modern day technology, composites are most promising materials

of recent interest. Metal matrix composites (MMCs) possess significantly improved

properties including high specific strength; specific modulus, damping capacity and good

wear resistance compared to unreinforced alloys. There has been an increasing interest in

composites containing low density and low cost reinforcements. Composite material is a

material composed of two or more distinct phases (matrix phase and reinforcing phase) and

having bulk properties significantly different from those of any of the constituents. Many of

common materials (metals, alloys, doped ceramics and polymers mixed with additives) also

have a small amount of dispersed phases in their structures, however they are not considered

as composite materials since their properties are similar to those of their base constituents

(Fly Ash property of steel are similar to those of pure iron) . Favorable properties of

composites materials are high stiffness and high strength, low density, high temperature

stability, high electrical and thermal conductivity, adjustable coefficient of thermal

expansion, corrosion resistance, improved wear resistance etc.

Fig 1.1: Composite Classification on Basis of Material Structure

The Matrix Phase(primary phase) having a continuous character, usually more ductile and

less hard phase and holds the reinforcing phase and shares a load with it. Whereas

Reinforcing Phase is Second phase (or phases) is imbedded in the matrix in a discontinuous

form, Usually stronger than the matrix, therefore it is sometimes called reinforcing phase.

Metal Matrix Composites are composed of a metallic matrix (Al, Mg, Fe, Cu

etc) and a dispersed ceramic (oxide, carbides) or metallic phase (Pb, Mo, W etc). Ceramic

reinforcement may be silicon carbide, boron, palumina, silicon nitride, boron carbide, boron

nitride etc. whereas Metallic Reinforcement may be tungsten, beryllium etc. MMCs are used

for Space Shuttle, commercial airliners, electronic substrates, bicycles, automobiles, golf



ISSN: 1548-7741

www.joics.org144

clubs and a variety of applications. From a material point of view, when compared to

polymer matrix composites, the advantages of MMCs lie in their retention of strength and

stiffness at elevated temperature, good abrasion and creep resistance properties. Most MMCs

are still in the development stage or the early stages of production and are not so widely

established as polymer matrix composites. The biggest disadvantages of MMCs are their high

costs of fabrication, which has placed limitations on their actual applications. There are also

advantages in some of the phyFly Ashal attributes of MMCs such as no significant moisture

absorption properties, non-inflammability, low electrical and thermal conductivities and

resistance to most radiations. MMCs have existed for the past 30 years and a wide range of

MMCs have been studied. Due to the poor wettability between the metal matrix and the

ceramic particles, the particulates tend to agglomerate in the matrix. External field forces are

needed to break up the clusters and help disperse the particles into the metal.

The strengthening mechanisms of the composites are different with different

kind of reinforcing agent morphology such as fibers, particulate or dispersed type of

reinforcing elements. In case of Fiber Reinforced Composite high strength of the reinforcing

phase restrict the free elongation of the matrix especially in its vicinity, whereas later is free

to elongate at some distance away from the former. This type of non uniform deformation of

the matrix leads to a shear stress at the matrix reinforcement interface which results tensile

stress at the reinforcing phase. Thus the stress is transferred to the reinforcing phase. In case

of Dispersion Strengthening composite the second phase reinforcing agents are finely

dispersed in the soft ductile matrix. The strong particles restrict the motion of dislocations

and strengthen the matrix. Here the main reinforcing philosophy is by the strengthening of

the matrix by the dislocation loop formation around the dispersed particles. Thus the further

movement of dislocations around the particles is difficult. And in case of particulate

reinforced composite the size of the particulate is more than 1 µm, so it strengthens the

composite in two ways. First one is the particulate carry the load along with the matrix

materials and another way is by formation of incoherent interface between the particles and

the matrix. So a larger number of dislocations are generated at the interface, thus material

gets strengthened.



ISSN: 1548-7741

www.joics.org145

2. EXPERIMANTAL PROCEDURE

2.1 Equipment and Consumables Used

Table 2.1 process parameters table

Fig 2.1 AA-2014 Specimen

Cast alloy 2014 series of castings are used because of the High strength provided by the high

copper and remaining contents and its contribution to fluidity Plus their response to heat

treatment which provides a variety of high-strength options. Further the Cast alloy 2014

series may be cast by a variety of techniques ranging from relatively simple sand or die

casting to very intricate permanent mold, lost Foam/lost wax type castings, and the newer

thixos casting and squeeze casting technologies.

Fig. 2.2 Fly Ash

Fly ash is a heterogeneous material. SiO2,

Al2O3, Fe2O3 and occasionally CaO are the

main chemical components present in fly ashes.

The mineralogy of fly ashes is very diverse.

The main phase encounterd are a glass phase,

together with quarts, mullite and the iron oxide

hematite, magnetic and /or magnetite. Other

phases often identified are cristobalite,

anhydrite, freelime periclase, calcite, sylvite,

halite, portlandite, rutile, and anatse.

Matrix Alloy AA 2014

Reinforcement Fly ash Of Size 5µm-300 µm

Wetting agent Magnesium (Mg)

Crucible Graphite Material With 1.5 Kg Capacity

Dies Mild Steel

Inert Gas Argon.

Ultrasonic Transducer 20Khz, 2000W

Electrical Resistance Furnace 1200°C

Chamber Size 12×12×18



ISSN: 1548-7741

www.joics.org146

2.2 Fabrication of Metal Matrix Composite

Aluminium MMC can be produced by different techniques. Some of them are: Stir

casting, forced vortex technique and Powder metallurgy technique. For manufacturing of

composite material by stir casting knowledge of its operating parameter are very essential.

Various process parameters like stirring speed, stirring temperature, reinforcement preheat

temperature, stirring time, inert gas, preheated temperature mould and powder feed rate. if

they properly controlled can lead to the improved characteristic in composite material.

An electric resistance heating unit was used to melt the AA2014 in the graphite

crucible. A titanium waveguide which was coupled with a 20 kHz, 2000w ultrasonic

converter was dipped into the melt for ultra sonic processing.

Fig 2.3 stir casting set up

The nano-sized Fly Ash particles were added into melts during the process from the top of the

crucible. The aluminum melt pool was well protected by the argon gas. The ultrasonic

processing temperature was controlled to 1000C above the alloy melting point (610

0C). An

ultrasonic power of 1880 watts from the converter was used to generate adequate processing

function inside the crucible. Totally four varieties of nano composites were prepared in which

the weight percent of the reinforcement was considered at 5%, 10%, 15% and 20% for the

chosen Nano size of 0.5 µm-300 µm fly ash particles. As observed during the process the

viscosity of the melts significantly increased with the nano-sized Fly Ash particles in the

melts. Thus after efficient ultrasonic processing a higher casting temperature of 760*c was

used to ensure the flow ability inside the graphite mould. Thus we obtain 4 nano composites

with different fly ash percentages in each and one raw AA2014 is also prepared to compare

and observe the values.



ISSN: 1548-7741

www.joics.org147

3. MICROSTRUCTURE STUDY

3.1 Metallurgical microscope Results

The material sample is prepared by polishing, etching, cutting, vapor deposition etc.

The methods are known collectively as metallographic as applied to metals and alloys, and

can be used in modified form for any other material, such as ceramics, glasses, composites,

and polymers. Two kinds of optical microscope are generally used to examine flat, polished

and etched specimens: a reflection microscope and an inverted microscope. Recording the

image is achieved using a digital camera working through the eyepiece. Here we are using an

inverted microscope of magnification 10x.to 60x. We obtain the images of the nine

specimens as follows:

The figure below shows the micro structural study for the cast aluminum alloy

without fly ash particles and ultrasonic processing. It can be observed clearly that the dendrite

grains are clearly revealed.

Fig 3.1: Microstructure of Raw AA2014

The figure below shows the micro structural study for the specimen containing matrix

material as AA2014 and the reinforcement material as fly ash for the weight percent of 5%.

From the below image we can observe the distribution of the fly ash particles in the AA2014.

The grain sizes observed are smaller than that of the cast aluminum alloy without fly ash

particles and ultrasonic processing.

Fig 3.2: Microstructure with 5% Wt of Fly Ash



ISSN: 1548-7741

www.joics.org148

http://en.wikipedia.org/wiki/Metallography

http://en.wikipedia.org/wiki/Ceramic

http://en.wikipedia.org/wiki/Glass

http://en.wikipedia.org/wiki/Polymer

http://en.wikipedia.org/wiki/Inverted_microscope

Fig 3.3: Microstructure with 10%Wt of Fly

The figure below shows the micro structural study for the specimen containing matrix

material as AA2014 and the reinforcement material as fly ash for the weight percent of 10 %.

From the below image we can observe the distribution of the fly ash particles in the AA2014.

The grain sizes observed are smaller than that of the cast aluminum alloy without fly ash

particles and ultrasonic processing.

3.2 Scanning Electron Microscopic Images

The image show the dispersion of the Nano Fly Ash particles in the AA2014 matrix

alloy. From the images it is clear that the Nano-sized Fly Ash particles (from 5 to 20 wt. % of

size 5µm) were well dispersed in the AA2014 matrix, as shown. Tiny scratches/cracks due to

polishing are displayed. High intensity ultrasonic waves have generated strong cavitations

and acoustic streaming effects during mixing. Transient cavitations have produced an

impulsive impact strong enough to break up the clustered particles and disperse them more

uniformly in the liquid .Figures shows SEM images of 10 wt% and 15 wt %.

Fig 3.4 scanning electron microscopic images



ISSN: 1548-7741

www.joics.org149

3.3 Electron Dispersion Microscope Image

It seems that the composite was protected well during fabrication since the oxidation

level is quite low. Since the average size of the fly ash particle is 5µm, it is very difficult to

use EDS spot analysis due to the limitation of the e-beam resolution in the instrument.

Therefore, mapping scanning was employed. Shows the distribution of the elements

aluminum (Al), fly ash, respectively. The results show that C is distributed uniformly, which

indicates a good dispersion of Fly Ash particles in matrix. From the mapping of Si element,

there are some concentrations from the eutectic Si of the alloy.

4. RESULTS AND DISCUSSION

The characterization of the strength is characterized by finding out the tensile testing.

For tensile testing the AL composite was cut according to the ASTME8 standards. The

overall length be 150mm, Guage length 70mm, Width 12.5mm, Width of gripped area 20mm.

The bulk Al cast alloy was cut according to the above standerds in Wire Edm process.

Fig 4.1: Al Cast Alloy ASTME8 Standards Fig 4.2:Tensile Testing Pieces

Fig 3.4 Electron Dispersion Microscope image



ISSN: 1548-7741

www.joics.org150

As observed from the above figures the specimens were subjected to failure almost at

the same location. This breaking of the specimens at the same location indicates the uniform

distribution of the composite particles in the specimens the stress strain curves were taken as

shown below:

Wt (%) UTS

0 345 MPa

5 373 MPa

10 385 MPa

15 341 MPa

20 318 MPa

Table 4.1 Ultimate Tensile strength Values Fig 4.3: Graph Showing UTS Vs Wt.(%)

The above observations clearly dissipates that as the weight percentage of the nano-particles

increase the ultimate tensile strength also increases and it is a positive sign to be observed.

4.1 Yield Point:

The Yield point is the point where the elastic deformation stops and the plastic

deformation starts. From the stress strain diagrams obtained the following observations are

made:

Wt. (%) YIELD

STRENGTH

0 271 MPa

5 305 MPa

10 322 MPa

15 268 MPa

20 247 MPa

Table 4.2 Values of Yield Point Fig 4.4 Graph Yield Strength Vs Wt%

0

50

100

150

200

250

300

350

0 5 10 15 20

Series1

fly ash particles wt%

050

100150200250300350400450

0 5 10 15 20

Series1

fly ash particle wt%Ult

imat

ete

nsi

le s

treg

th (

)Mp

a



ISSN: 1548-7741

www.joics.org151

From the Fig 4.2 observations it can be clearly understood that the as the percentage

of the nano particles in the composite increase the yield strength value increases which is a

positive phenomenon to be observed.

4.2 Ductility

Ductility is measured in the terms of the percentage elongation.The elongation

percentage for the raw AL cast alloy is said to be 2.6%. The following observations are

observed as the percentage of the Fly Ash particles increase.

Wt. (%) 5(nm)

0 12%

5 9.1 %

10 8.4 %

15 8.2 %

20 7.8%

Table 4.3.Values of % Elongation Fig 4.5: Graph elongation% Vs Wt%

The percentage of elongation followed the gradually decreased trend on the addition

of Fly Ash content at all the sizes and percentages.The reason could be due to the effect of

Embrittlement of the composite due to the initiation of localized crack at the Fly Ash-

AA2014 interface. The percentage elongation of all the varieties of the nano composites is

slightly lesser than that of the base alloy.

4.3 Hardness

We used Brinell hardness for our experiment. The Brinell harness number is calculated by

dividing the load applied by the surface area of the indentation. The results obtained are the

values obtained show that as the composition and the percentage values are increased the

hardness values also increased which is a good sign to be noticed.

0

2

4

6

8

10

12

14

0 5 10 15 20

Series1

fly ash particles wt%



ISSN: 1548-7741

www.joics.org152

Wt. (%) 5 (nm)

0 62 BHN

5 75 BHN

10 81 BHN

15 71 BHN

20 58 BHN

Table 4.4 Hardness Values Obtained Fig 4.6 Graph Hardness Vs Wt (%)

5. CONCLUSION

AA2014 has been selected as matrix alloy as it is readily castable. The mechanical

properties such as hardness, Young’s modulus, tensile strength will be studied and compared

with those of the base alloy. The correlation of the properties with respect to the variation of

the processing parameters, viz., weight percentage and particle size will be done. The weight

percentage of nano-sized Fly Ash will be varied from 0 to 20% in the step size of 5 while the

average size of the particle will be taken at 0.5µm-300µm. In addition, the analysis of the

micro-structural properties of metallurgical structure and grain size were also be carried. The

maximum ultimate strength 385Mpa at 10 weight %, the maximum yield point is 322Mpa at

10 weight %, the maximum ductility is 9.1% at 5 weight % and the maximum hardness 81

BHN at 10 weight % are observed. It can be observed from the SEM images and EDS

analysis that the particles are well distributed in the base alloy and agglomeration of the

particles are greatly reduced, and the melt pool is well protected from the atmospheric

conditions

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20

Series1

fly ash particles wt%A



ISSN: 1548-7741

www.joics.org153

6. REFERENCES

1. S.Bandyopadhay, T. Das , and P.R. Munroe ,Metal Matrix Composites -The Light Yet

2. Stronger Metals For Tomorrow, A Treaise On Cast materials, p-17-38.

3. T.W.Clyne, (2001), Metal Matrix Composites: Matrices And Processing,

Encyclopedia Of Materials : Science And Technology ,P- 8.

4. Composite Materials: Engineering And Design By F.L.Matthews And R.D.Rawlings,

Chapman & Hall Publication.

5. Estimation Of Cavitation Pressure To Disperse Carbonnano Tubes In Aluminum

Metal Matrix Nano Composite.By,Suneel D.,Nageswar Rao D, Satyanarayana

.Ch,Pawan Kumar Jain.

6. Ultrasonic Cavitation Assisted Fabrication And Charecterization of A356 Metal

Matrix Nano Composite Reinforced With Fly Ash,B4c,Cnts.

7. Estimation Of Cavitation Pressure To Disperse Carbon Nano Tubes In Aluminium

Metal Matrix Nano Composites.

8. Fabrication And Study Of The Mechanical Properties Of AA2024 Alloy Reinforced

With B4c Nano Particles Using Ultrasonic Cavitation Method.

9. Effect of Micro Structural Changes on Mechanical Properties of Friction Stir Welded

Nano Fly Ash Reinforced Aa6061 Composite.

10. Micro Structure And Micro Hardness Of Fly Ash Nano Particle Reinforced

Magnesium Composites Fabricated By Ultrasonic Meathod; By Jie Lan, Yong Yang,

Xiaochun Li.

11. Processing Micro-structural And Tensile Properties Of Nano Sized Al2o3 Particle

Reinforced Aluminium Matrix Composites; By Hai Su, Wenli Gao, Zhaohui Feng,

Zheng Lu.

12. Ultrasonic Cavitation Based Nano Manufacturing Of Bulk Aluminium Matrix Nano

Composites.; By Yong Yang, Xiaochun Li.

13. Ultrasonic Nano Dispersion Technique Of Aluminum Alloy And Carbon Nano Tubes

For Automotive Parts Application By V.Giridhar; R.S.Arun Raj, R.Dhisondhar.



ISSN: 1548-7741

www.joics.org154

evaluation of mechanical properties and ...joics.org/gallery/ics-1175.pdfmicrostructural study of...

Documents