Michael J. DemkowiczDepartment of Materials Science and Engineering, Texas A&M University,

College Station TX, 77843

SSAP symposiumFeb. 26-27, 2020Washington, DC

This work was supported by the Department of Energy, National Nuclear Security Administration, under Award no. DE-NA0003857

• Lead: Texas A&M University, director: M. J. Demkowicz (MSEN)• Collaborating institutions: UCSB, U. Michigan, U. Connecticut• Goals:

• Discover, understand, and predict the influence of microstructural heterogeneities—such as interfaces, inclusions, and porosity—on the high strain rate (>104/s) mechanical response of multiphase metallic materials (M3)

• Apply this fundamental understanding to certification of high-performance additively manufactured M3

• Train the next generation of leaders in stockpile stewardship through close collaboration with partners at NNSA labs

Passionate faculty

Developing new capabilities

Training stewardship science leaders

NNSA/SSAA center of excellence, Est. July 2018

Who we are (see credds.tamu.edu for more details)Four institutions:

PI: M. J. Demkowicz Co-PI: I. J. Beyerlein Co-PI: A. Misra Co-PI: A. Dongare

28 team members:

7 external advisors:

• 10 faculty • 17 PhD students • 4 postdocs • 1 tech • 1 admin officer

Ellen Cerreta (LANL), Mukul Kumar (LLNL), Brad Boyce (SNL), Don Brenner (NCSU), Marisol Koslowski (Purdue), Lori Graham-Brady (JHU), Pradeep Guduru (Brown)

Faculty profilePrior employment

at NNSA labs (LANL)

NAE members Early career

Demkowicz

Misra

Beyerlein

NRC fellow at US-ARO

PollockPharr

NeedlemanMazumder

Selected honors at LANL:• LANL Fellow (Misra)• Oppenheimer fellow (Beyerlein)• Director’s fellow (Demkowicz)• EFRC directors (Misra, Beyerlein)

• Mazumder: direct metal deposition• Needleman: fracture modeling• Pharr: nanoindentation• Pollock: advanced metallic materials

Dongare

Senior facultyHartwig Zok

High strain rate testing

SPD processing

Student profile

• 17 PhD students currently supported by CREDDS, all US persons:

• 6 at TAMU, 4 at UM, 5 at UCSB, 2 at UConn

• 1st year (2):• UCSB: Lauren Poole, Wyatt Witzen

• 2nd year (7):• TAMU: Liya Semenchenko, Emmeline Sheu,

Ta Duong, Chris Walker• UM: Daniel Yin• UCSB: Toby Francis• UConn: Marco Echeverria, Jessica Maita

• 3rd year (2):• TAMU: Wesley Higgins, Edwin

Chiu• 4th year (4):

• UM: Ethan Sprague, Max Powers• UCSB: Avery Samuel, Paul

Christodoulou• 5th year (1):

• UM: Ben Derby

Multiphase metallic materials (M3)

Cu-Nb composite made by severe plastic deformation

Cu-W composite made by liquid metal dealloying

Additively manufactured Ni-base alloy Inconel 718

Microstructure is the key difference between M3 and single crystal solids

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Twins, precipitates, impurities, porosity

Misfit dislocations, disconnections, facets

Texture, grain shape Crystallographic character, complexions

Phase fraction, composite morphology

Interface connectivity

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Twins, precipitates, impurities, porosity

Cu/Ta multilayer under shock loading

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Misfit dislocations, disconnections, facets

General GB in Cu

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Texture, grain shape

Polycrystalline Ta

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Crystallographic character, complexions

GB character effect on intergranular fracture

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Phase fraction, composite morphology

DMD-CuFe

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Interface connectivityMixed strong/weak grain boundaries in a polycrystal

Levels of microstructure

Defect

Composite

Mesoscale

Phase Interface

Twins, precipitates, impurities, porosity

Misfit dislocations, disconnections, facets

Texture, grain shape Crystallographic character, complexions

Phase fraction, composite morphology

Interface connectivity

High strain rate response of M3

HAGB

J. P. Escobedo et al., J. Appl. Phys. 110, 033513 (2011)

Spall plane

Spall failure in polycrystalline Cu

R. F. Zhang et al., Scripta Mater. 68, 114 (2013)

Interfacial plasticity in Cu/Nb multilayers

TwinningNo twinning

PVD interfaces

ARB interfaces

An integrated research strategyAdvanced processing Pre-test characterization

High strain-rate testing Post-test characterization

Physics-based modeling

UM, TAMU, LANL TAMU, UCSB, UM

UCSB, UConn, TAMU, LANL, LLNL

TAMU, UCSB, LANL, LLNL UM, UCSB

Data-driven inference and optimization

UCSB, TAMU

Simultaneous testing and simulation of equivalent

microstructures

Optimization of successive experiments and microstructures to address science hypotheses

Data-based integration of experimental and

modeling results

New capability:Performance certification for AM M3

New capabilities:• High strain rate nanoindentation• High speed in situ DIC

Our work follows an iterative

”design-synthesize-test” (DST) model

Thrust 1: effect of interface microstructure on flow localization in high strength M3 under dynamic loading

The key to certification of additive and advanced manufactured M3 is linkinginterfacial microstructure with unit mechanisms of flow localization

Predictive models

Advanced Manufacturingof Novel M3

PVD DMD SPD

Interface Microstructure: Spacing Shape Crystallography, texture Defect structureChemistry

Certification Metrics- Strength level- Uniform vs localized

plastic flow

SHPB, Gas gun performance test

atomistic mesoscaleMulti-scale modeling

unit mechanisms:Twin and/or Slip Shear band formation

High-throughput Dynamic Behavior: Interface unit mechanisms

HRTEM: Twin and/or SlipHigh rate nanoindenter

Flow Localization Behavior:Interface effects measured in situ

in situ SEM nanomechanics in situ DCS

Shear band

Thrust 2: effect of interface microstructure on spall response of high strength M3 under dynamic loading

The key to certification of additive and advanced manufactured M3 is relating interfacial microstructure with void evolution

Advanced Manufacturingof Novel M3

PVD DMD SPD

Interface Microstructure: Spacing CrystallographyDefect structureChemistryPhase Shape and texture

Certification Metrics- Spall strength- Delocalized

void evolution

Flyer plate performance test

atomistic

Microstructure-sensitive modeling

Nucleation Heterogeneous stress states

High rate mechanical response: Mechanics and microstructure of void evolution

SHPB

DIC

Gas Gun

Incipient voids; coalesced voids

HRTEM.TEM/SEM

Data analysis and modeling

mesoscale

3D TriBeam Void at 4P

Microstructural CharacterizationInterface directed void evolution

Micro-CT

Example: flow localization in laminatesProcessing of Cu/Ta M3 by

accumulated roll bonding (ARB)

CREDDS goals:• Process layered

composites for plate impact testing

• Contrast Cu/Ta with Cu/Nb: comparable chemistry, but large density contrast

Engagement with LANL:• Spring 2019 working

at Sigma Division with D. Coughlin

• Optimize processing• Characterize products

Hydrocode modeling at SNL (ongoing)

Edwin Chiu(TAMU)

Avery Samuel (UCSB)

Flier plate impact testing (LANL, summer 2020)

LiyaSemenchenko

(TAMU)

Atomistic simulations (Dongare, Echeverria)Post-test characterization (Misra, Derby)

In situ testing at the Dynamic Compression Sector (Dongare, Misra, Kumar)

Example: ”weakest links” for spall failureDevelopment of 3-D FFT CP

mesoscale models

CREDDS goals:• Simulate site-specific

damage initiation in M3 under spall

• Apply to performance certification of AM M3

Engagement with LANL:• Spring 2019 working

at T-Division with Ricardo Lebensohn

• Improve models• Validate against

experiments

3-D reconstruction using TriBeam

Toby Francis (UCSB)

Compare to spalled samples from LANL

Multiphase M3 (Hartwig, Levin, Mazumder, Sprague)

Microstructure analysis (Demkowicz, Pollock)

Coil/magnet assembly

Leaf springs

Capacitance gauge

Indenter / Tip

Sample

Load Frame

New capabilities: >104/s nanoindentation

• High speed micromechanical testing• Nanoindentation• Micropillar compression

• High speed imaging• In situ digital image correlation (DIC)• High speed ultraviolet microscopy

George Pharr(TAMU)

Phani and Oliver, Materials 10, 663 (2017)

New capabilities: rapid screening of materials for dynamic response

High strain rate deformation during high speed cutting

Images courtesy of Dinakar Sagapuram (TAMU)

Continuum modeling of cutting

Umair Bin Asim(TAMU)

Bayesian inference of mechanical response by matching models to experiments

Students in residence at NNSA labs

• Five CREDDS students with ~semester-long stints at NNSA labs in FY1:

• Our goal is to send all of our PhD students for at least one such internship at a NNSA lab in the course of their PhD

• We are seeking to expand internship opportunities at SNL and LLNL

Paul Christodoulou Ben Derby Liya Semenchenko Avery Samuel

LANL, Ricardo Lebensohn (MST-8)

LANL, Kevin Baldwin (CINT)

LANL, Dan Coughlin (Sigma)

LANL, SaryuFensin (MST-8)

(UCSB) (Michigan) (TAMU) (UCSB)Marco Echeverria

LLNL, TomorrHaxhimali, Robert

Rudd (MSD)

(Connecticut)

Students in residence at NNSA labs

• Five CREDDS students with ~semester-long stints at NNSA labs in FY2:

• Our goal is to send all of our PhD students for at least one such internship at a NNSA lab in the course of their PhD

• We are seeking to expand internship opportunities at SNL and LLNL

Paul Christodoulou Edwin Chiu Liya Semenchenko Emmeline Sheu

LANL, Ricardo Lebensohn (MST-8)

SNL, John Mitchell (CCR)

LANL, SaryuFensin (MST-8)

LANL, Darrick Williams (CINT)

(UCSB) (TAMU) (TAMU)Ethan Sprague

LLNL, Ibo Matthews (NIF)

(Michigan)(TAMU)

CREDDS alumni transitioning to NNSA labs

We are seeking to create a pipeline to SNL and LLNL, as well

Ben Derby

Postdoc, LANL MST-8 (starts May 2020)

(Michigan PhD)Zachary Levin

TSM, LANL MST-16 (started Jan. 2020)

(TAMU postdoc)

Technical collaborations with NNSA labs

564K cycles 644K cycles 724K cycles

Collaboration between TAMU and CINT/SNL on crack healing during fatigue loading

Hydrostatic stress due to CTB migrationCollaborating with Boyce, Barr, Hattar,

Bufford (SNL)

Ta Duong(TAMU)

Crack healing in metals is an example of how microstructure modifies mechanical response

Outreach to undergraduates

CREDDS supported 12 undergraduate researchersSummer USRG students at TAMU Rowan Baird won 1st place in

the TAMU REU/USRG poster competition

Engagement between two NNSA centers at TAMU: CREDDS and CENTAUR

This effort builds a graduate recruiting pipeline for all SSAP programs

Organization of technical meetings• CREDDS PhD student, Max Powers (Michigan), co-

organized a student-run symposium at TMS 2019: “Science Policy Within the Materials Research Community”

• Demkowicz was on the program committee of LANL-sponsored workshop “Adaptive Sample Preparation and Target Fabrication for High-Throughput Materials Science”

• Dongare and Beyerlein co-organized fall 2019 MRS symposium “Extreme Mechanics”

• Dongare is co-organizing a TMS 2020 symposium on “Understanding and Predicting Dynamic Behavior of Materials”

• In 2021-2022 (FY4), CREDDS will hold a week-long summer school on materials research topics in stockpile stewardship

Poster presenters at 2020 SSAP symposiumEdwin Chiu

(TAMU)Umair Bin Asim

(TAMU)Max Powers(Michigan)

Lauren Pooler(UCSB)

Daniel Yin(Michigan)

Frank Zok(UCSB)

Ethan Sprague(Michigan)

Emmeline Sheu(TAMU)

Ted Hartwig(TAMU)

Ta Duong(TAMU)