U.S. Army Research, Development and Engineering Command
U.S. Army Research, Development and Engineering Command
The “Nanocrystalline Metals” Renaissance of the 21st Century: Tailoring “Bulk” Nanocrystalline Metals for Enhanced Thermal Stability and Mechanical Properties
Mark Tschopp, Heather Murdoch, Laszlo Kecskes, Kris Darling Lightweight & Specialty Metals Branch U.S. Army Research Laboratory
Approved for Public Release / Distribution Unlimited
U.S. Army Research, Development and Engineering Command
The “Nanocrystalline Metals” Renaissance of the 21st Century: Tailoring “Bulk” Nanocrystalline Metals for Enhanced Thermal Stability and Mechanical Properties
Mark Tschopp, Heather Murdoch, Laszlo Kecskes, Kris Darling Lightweight & Specialty Metals Branch U.S. Army Research Laboratory
Approved for Public Release / Distribution Unlimited
U.S. Army Research, Development and Engineering Command
The “Nanocrystalline Metals” Renaissance of the 21st Century: Tailoring “Bulk” Nanocrystalline Metals for Enhanced Thermal Stability and Mechanical Properties
Mark Tschopp, Heather Murdoch, Laszlo Kecskes, Kris Darling Lightweight & Specialty Metals Branch U.S. Army Research Laboratory Mark de’ Medici
Approved for Public Release / Distribution Unlimited
The “Renaissance” period
"Renaissance" (French for "rebirth“) perfectly describes the intellectual and economic changes that occurred in Europe from the 14th through the 16th centuries.
In the feudal structure of the Middle Ages, the nobles who lived in the country provided the king with protection in exchange for land. Peasants worked the land for the nobles, for which they received protection and their own small parcels of land. These rural peasants worked from sunup to sundown, but even the nobles had few creature comforts. In feudal cities, where there was a small middle-class population, life was a little easier and individuals had the freedom to pursue whatever trade or industry they liked. In the late Middle Ages, when the threat of invasion from barbarians had lessened, people left the country for towns and cities so they could engage in more profitable pursuits.
The “Renaissance” period
"Renaissance" (French for "rebirth“) perfectly describes the intellectual and economic changes that occurred in Europe from the 14th through the 16th centuries.
In the feudal structure of the Middle Ages, the nobles who lived in the country provided the king with protection in exchange for land. Peasants worked the land for the nobles, for which they received protection and their own small parcels of land. These rural peasants worked from sunup to sundown, but even the nobles had few creature comforts. In feudal cities, where there was a small middle-class population, life was a little easier and individuals had the freedom to pursue whatever trade or industry they liked. In the late Middle Ages, when the threat of invasion from barbarians had lessened, people left the country for towns and cities so they could engage in more profitable pursuits.
The “Renaissance” period
"Renaissance" (French for "rebirth“) perfectly describes the intellectual and economic changes that occurred in Europe from the 14th through the 16th centuries.
Life in the city was soon to change drastically. During the late Middle Ages and early Renaissance (1350-1450) the bubonic plague, also called the "Black Death," devastated one half of the population of Europe. The plague, which was almost always fatal, spread most rapidly in cities, where people were in close contact with each other. The only way to avoid the disease was to leave the city for the country. This solution was, unfortunately, available only to those wealthy enough to make the trip.
The “Renaissance” period
"Renaissance" (French for "rebirth“) perfectly describes the intellectual and economic changes that occurred in Europe from the 14th through the 16th centuries.
The population decrease caused by the plague led to an economic depression. As incidence of the plague decreased in the late fifteenth century, populations swelled, creating a new demand for goods and services. A new middle class began to emerge as bankers, merchants, and tradespeople once again had a market for their goods and services. As the fortunes of merchants, bankers, and tradespeople improved, they had more than enough money to meet their basic needs for food, clothing, and shelter. They began to desire larger, more luxurious homes, fine art for these residences, sumptuous clothing to show off their wealth in public, and exotic delicacies to eat. These desires of the middle class stimulated the economy.
Army Research Laboratory What does the Army Research Laboratory do?
Army Research Laboratory The primary mission of the U.S. Army Research Laboratory is to “Provide the underpinning science, technology, and analysis that enables full-spectrum operations.” Army of Today
Rapid Innovation
Fundamental Research That Accelerates Development for Future Needs of the Army Transformative Vision
Armed with Science
State of the Art, Art of the Possible!
Army of the Future
Army Research Laboratory The primary mission of the U.S. Army Research Laboratory is to “Provide the underpinning science, technology, and analysis that enables full-spectrum operations.”
WMRD (Weapons & Materials Research Directorate)
Jones, T., et al. ARL-TR-4664, ARL-TR-4664
Army Research Laboratory The primary mission of the U.S. Army Research Laboratory is to “Provide the underpinning science, technology, and analysis that enables full-spectrum operations.”
WMRD ARL-TR-4664
Capability
Old Paradigm
Weight
Materials research that focuses on reducing weight as well as increasing strength and/or functionality can help extend operating ranges of vehicles, increase available mission scope and add additional sensors or payloads.
Army Research Laboratory The primary mission of the U.S. Army Research Laboratory is to “Provide the underpinning science, technology, and analysis that enables full-spectrum operations.”
WMRD e.g., Heat Treatment, Severe Plastic Deformation
Capability
Capability
Old Paradigm
Weight
e.g., Alloy Change, Material Change
Weight
Materials research that focuses on reducing weight as well as increasing strength and/or functionality can help extend operating ranges of vehicles, increase available mission scope and add additional sensors or payloads.
Army Research Laboratory The primary mission of the U.S. Army Research Laboratory is to “Provide the underpinning science, technology, and analysis that enables full-spectrum operations.”
WMRD
New Paradigm
Capability
Capability
Old Paradigm
Weight
Weight
Materials research that focuses on reducing weight as well as increasing strength and/or functionality can help extend operating ranges of vehicles, increase available mission scope and add additional sensors or payloads.
Army Research Laboratory
What is the underlying fundamental science that contributes to performance in these applications? TODAY’S SEMINAR: Innovative Materials Science and Design of “Bulk” Nanocrystalline Metals
GBs in Nanocrystalline At Small Grain Sizes Macroscopic Deformation is Governed To a Large extent By GB-Mediated Processes
10 nm ~ 30 vol% Defects
10%
1%
As grain size decreases to the nanocrystalline regime (< 50 nm), the volume fractions of grain boundaries and triple junctions are increased, which leads to different properties.
Smaller is Better! Nano-Fe surpassing previous Steels!!!
Youssef, Scattergood, Murty, APL (2005)
Yield Strength (MPa)
1000% Increase in Mechanical Strength!!!
Nanocrystalline materials have a corresponding increase in mechanical properties and changes in the deformation mechanisms due to the increased fraction of grain boundaries and the peasants rejoiced…
Smaller is Better? T = 100 C Pure Cu
However, nanocrystalline materials have problems pertaining to thermal stability, which limits processing techniques as well as applications at moderate to high (and sometimes low) temperatures. S.Simoes, R.Calinas, P.J. Ferreira, M.T. Vieira, F. Viana and M.F. Vieira, Mat. Sci. For. Vols. 587, 2008, p 483-487. S.Simoes, R.Calinas, P.J. Ferreira, M.T. Vieira, F. Viana and M.F. Vieira,, Nanotech. 21 2010 pg 145701 .
aaaah…
Outline ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing:
Powder Consolidation (ECAE Processing)
Thermal Stability
Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Outline ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing:
Powder Consolidation (ECAE Processing)
Thermal Stability
Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
A Processing Introduction: High Energy Mechanical Alloying
Motivation: While many nanocrystalline processes focus on electrodeposition and vapor deposition, we are interested in creating bulk parts and materials with dimensions greater than 1 mm.
Mechanical alloying is a scalable powder metallurgy process for generating bulk nanocrystalline parts!
Mechanical Alloying can be applied to: Nanocrystalline Alloys, Amorphous Metals, Nanostructured Composites, Energetic Materials, Intermetallics, High Entropy Alloys, Solid State Foaming, Thermoelectrics, etc.
A Processing Introduction: High Energy Mechanical Alloying
Milling Time
Grain Size Reduction
Al-Mn
Fe-Zr
With increasing milling time, the mixing within powders increases, solute can be forced into solution, particles can be dispersed, and the grain size is reduced! KA Darling, AJ Roberts, L Armstrong, D Kapoor, MA Tschopp, LJ Kecskes, SN Mathaudhu, MSEA 589, 2014, pg. 57-65 KA Darling, BK VanLeeuwen, JE Semones, CC Koch, RO Scattergood, LJ Kecskes, MSEA , 528, 2011, pg. 4365-4371
A Processing Introduction: High Energy Mechanical Alloying
Nanocrystalline Material Processing Elemental Powders
High energy Mechanical Alloying
Nanostructured Powder
Fast Kinetic Studies & Characterization
Consolidation & Mechanical Testing
Nanocrystalline Material Process Flow Path
Critical Step in Nanocrystalline Preparation: Powder consolidation (e.g., sintering) requires temperatures greater than 0.5Tm (melting temperature). Thermal stability of nanocrystalline grain size is important!
Surface Nanocrystallization: Surface Mechanical Attrition Treatment
High Energy Cryogenic Surface Mechanical Attrition Treatment
A
B
C
Surface Mechanical Attrition Treatment (SMAT) produces ultrafine or nanocrystalline grains at the surface. At ARL, we have used cryogenic SMAT to further refine the grain size (60% smaller) through a change in deformation mechanism at the surface (dislocation based to shear band based). KA Darling, MA Tschopp, AJ Roberts, J Ligda, L Kecskes, Scripta Mat. 69, 2013, pg. 461-464.
Solid State Foaming:
Exceeding the Theoretical Limit of Porosity
Additive Expansion by the Reduction of Oxides (AERO)
Developed a new solid state foaming processing route whereby intraparticle expansion enables porosity levels that exceed 70% porosity (previously identified as the theoretical limit for solid state foaming). Reconstructing a 3D microstructure shows pore widths and wall thicknesses on the order of 1 micron. Parts have been produced with ~70% porosity. MA Atwater, KA Darling, MA Tschopp, Adv. Engr. Mat. 2014 (selected for cover image).
Outline ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing:
Powder Consolidation (ECAE Processing)
Thermal Stability
Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Achieving Stability:
Kinetic and Thermodynamic Approaches
Pure Cu
2 0 Qm v M P M 0 exp r RT
v = velocity of grain boundary M = mobility of grain boundary P = pressure on grain boundary M0 = pre-exponential factor Qm = activation energy for GB mobility γ0 = interfacial energy per unit area r = mean grain radius
Two approaches for thermal stability: Kinetic (M) and Thermodynamic (γ) S.Simoes, R.Calinas, P.J. Ferreira, M.T. Vieira, F. Viana and M.F. Vieira, Mat. Sci. For. Vols. 587, 2008, p 483-487. S.Simoes, R.Calinas, P.J. Ferreira, M.T. Vieira, F. Viana and M.F. Vieira,, Nanotech. 21 2010 pg 145701.
Achieving Stability:
Kinetic Grain Size Stability
Kinetic (M)
Qm M M 0 exp RT http://aluminium.matter.org.uk/
Pinned Grain Boundary
The kinetic approach for thermal stability relies on second phase particles, pores, and solute drag to pin grain boundaries and reduce their mobility. However, the grain boundary mobility follows an Arrhenius temperature dependence.
Achieving Stability:
Thermodynamic Grain Size Stability
Thermodynamic (γ)
Before segregation
After segregation
Solvent (B) Solute (A) Grain boundary
Reduction in Energy
The thermodynamic approach for thermal stability relies upon a reduction in grain boundary energy by solute segregation to the boundary, thereby reducing the driving force for grain growth (i.e., lowering the grain boundary energy).
Outline ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing:
Powder Consolidation (ECAE Processing)
Thermal Stability
Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Thermodynamic Stability: Solute Segregation
Visual representation of thermodynamic stability changes as function of grain size, solute fraction, and temperature
Developed a methodology that utilizes thermodynamic principles and experimental data to predict solutes that would tend to stabilize the nanocrystalline grain structure. MA Atwater, KA Darling, ARL-TR-6007; MA Tschopp, KA Darling, MA Atwater, et al. ARL-TR-6743; KA Darling, MA Tschopp , BK Vanleeuwen, MA Atwater, ZK Liu, Comp. Mat. Sci. (2014)
Thermodynamic Stability: Solute Segregation
Thermodynamic Stability Map
Experimental Validation
(1294 binary systems)
The present thermodynamic stability model agrees with previously measured stabilized grain sizes as a function of temperature. Recently, it has been extended to map all solutes in our database as well as the stabilizing solute concentration. MA Tschopp, KA Darling, et al. ARL-TR-6743; KA Darling, MA Tschopp, BK Vanleeuwen, MA Atwater, ZK Liu, Comp. Mat. Sci. (2014)
Thermodynamic Stability: Solute Segregation
The present thermodynamic stability model agrees with previously measured stabilized grain sizes as a function of temperature. Recently, it has been extended to map all solutes in our database as well as the stabilizing solute concentration. Tschopp, M.A., Murdoch, H.A., Kecskes, L.J., Darling, K.A., JOM (2014); KA Darling, MA Tschopp , BK Vanleeuwen, MA Atwater, ZK Liu, Comp. Mat. Sci. (2014).
Achieving Stability:
Thermodynamic Grain Size Stability
Thermodynamic stability is a function of 1. Grain size 2. Solute fraction 3. Temperature
Thermodynamic Stability:
Thermokinetic Model for Grain Growth
Towards a predictive grain growth model
Sensitivity Analysis
QL
~25% increase (300 C)
Model extended to account for temperature dependence
T Model overly sensitive to temperature
> 300% increase (100 C)
High temperature XRD measurements
A thermokinetic model that incorporates the thermodynamics and kinetics of grain growth has been extended to include temperature dependence of grain growth in nanocrystalline materials using high temperature XRD measurements. MA Tschopp, KA Darling, MA Atwater, KN Solanki, ARL TRL, in press.
Grain Boundaries in nc Metals: Atomistic Simulations of Segregation
Atomistic simulations are used to quantify segregation behavior and long term dynamics of substitutional and interstitial species (solute, impurities, point defects) at the grain boundary and how grain boundary character (atomic structure) affects segregation. MA Tschopp et al. (2011) Scripta Materialia; MA Tschopp et al. (2012) PRB; NR Rhodes et al. (2013) MSMSE; KN Solanki et al. (2013) Met Trans; MA Tschopp et al. (2014) JAP.
Outline ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing: Thermal Stability
EXAMPLE: PowderCu-Ta Consolidation (ECAE Processing) Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Microstructural Evolution: Cu Grain Size
Increasing Temperature
Cu-Ta TEM
Grain Growth Peak
nc CuTa
0
100
200
300
400
Temperature Increase 500
600
700
800
900
DSC Ave Cu GS 6 nm
to
20 nm
Ave Ta 25 nm
to
130 nm
DSC measurements combined with interrupted SEM/TEM can show the evolution of grain size and particle size with increasing temperature. First, the grain size increases (grain growth regime). KA Darling, AJ Roberts, Y Mishin, SN Mathaudhu, LJ Kecskes, J. Alloys. Comp. 573, 2013, pg. 142-150
Microstructural Evolution: Ta Particle Size
Increasing Temperature
Cu-Ta SEM
Grain Growth Peak
nc CuTa
0
100
200
300
400
Temperature Increase 500
600
700
800
900
DSC Ave Cu GS 6nm
to
20nm
Ave Ta 25nm
to
130 nm
DSC measurements combined with interrupted SEM/TEM can show the evolution of grain size and particle size with increasing temperature. Next, precipitation occurs and the Ta particle size increases. KA Darling, AJ Roberts, Y Mishin, SN Mathaudhu, LJ Kecskes, J. Alloys. Comp. 573, 2013, pg. 142-150
Thermal Stability:
Molecular Dynamics Modeling
Pure Cu Anneal at 750 K for 0.4 ns
Cu-6.5 at% Ta Anneal at 750 K for 24 ns
Cu-6.5 at% Ta Anneal at 1100 K for 24 ns
Molecular dynamics simulations of pure Cu and Cu-6.5%Ta show very different responses with respect to grain size stability. At 750 K, Ta stays at the grain boundaries. At 1100 K, Ta forms clusters! T Frolov, KA Darling, LJ Kecskes, Y Mishin, Acta Mat. 60, 2012, pg. 2158-2168
Thermal Stability:
TEM Evidence of Ta clusters
Atomic Clusters of Ta Dislocation
BCC TEM analysis shows the formation of large and small Ta clusters. Notice the string of small Ta clusters similar to the molecular dynamics simulations. KA Darling, AJ Roberts, Y Mishin, SN Mathaudhu, LJ Kecskes, J. Alloys. Comp. 573, 2013, pg. 142-150
Molecular Dynamics Modeling: Cluster and Grain Boundary Pinning
Grain stability in nc Cu (1200 K)
Initial
Final (18 ns)
Grain stability in nc Cu-5%Ta (1200 K)
Initial
Molecular dynamics simulations of pure Cu and Cu-5%Ta show very different responses with respect to grain size stability. This mechanism can be attributed to kinetic pinning. T Frolov, KA Darling, LJ Kecskes, Y Mishin, Acta Mat. 60, 2012, pg. 2158-2168
Final (18 ns)
Microstructural Evolution:
High Energy Mechanical Alloying of Cu-Ta
MD simulations
Atom probe results show a portion of the Ta forms clusters with the balance (4 at%) in a solid solution with Cu, similar to molecular dynamics simulations.
Stabilizing Grain Size Through:
Kinetic and Thermodynamic Mechanisms
Mean 166 nm Median 160 nm STDEV 50 nm
Nanocrystalline Cu-Ta isothermally annealed at 1040°C or 97%TM for 4 hrs.
Stabilizing Grain Size Through:
Kinetic and Thermodynamic Approaches
Vickers Hardness (GPa)
5.3
Cu 10at% Ta
4.8
Nanocrystalline Pure Cu
4.3
Melting Point of Cu
Avg Grain size 10 nm
3.8 3.3
Conventional Cu
Avg Grain size 60 nm
2.8
2.3 Avg Grain size 200 nm
1.8 Avg Grain size 5 mm
1.3 0.8 0.3 0
200
400
600
800
1000
Annealing Temperature (oC) Nanocrystalline Cu-10%Ta isothermally annealed at 1040°C or 97%TM for 4 hrs.
Outline ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing:
Powder Consolidation (ECAE Processing)
Thermal Stability
Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Powder Consolidation: High Temperature ECAE
Route BC 90°
Three ECAE conditions: a) Cu- 1%Ta 700 °C b) Cu-10%Ta 900 °C c) Cu-10%Ta 700 °C
High temperature ECAE processing route 4Bc was utilized for bulk consolidation Tschopp, M.A., Murdoch, H.A., Kecskes, L.J., Darling, K.A., JOM (2014); Darling, K.A., Tschopp, M.A., et al., Acta Materialia (2014)
Post-ECAE Processing: Cu Grain Size Distributions
mean grain size
168 nm
213 nm
70 nm
Cu Darling, K.A., Tschopp, M.A., Kecskes, L.J., et al., Acta Materialia (2014).
Post-ECAE Processing:
Ta Particle Size Distributions
Grain Boundary vs Lattice Diffusion: Bimodal Particle size Distribution • Large Ta particles located on grain boundaries • Small particles located within the lattice
• Distribution a function of both temperature and Ta concentration • Both small and large particle fraction increase in size with temperature
Darling, K.A., Tschopp, M.A., Kecskes, L.J., et al., Acta Materialia (2014).
ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing:
Powder Consolidation (ECAE Processing)
Thermal Stability
Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Mechanical Properties Capabilities
Indentation Creep Shear Punch Test
1 mm
A combination of mechanical testing is used to assess the properties and performance of nanocrystalline materials, even at high strain rates and high temperatures, including: shear punch test, indentation creep, miniature tension (FIB), split Hopkinson bar, micropillar compression, dynamic hardness, etc.
Mechanical Properties
Shear Punch Test
Shear punch testing probes the shear, relaxation (creep), and strain rate sensitivity response of nanocrystalline materials at small volumes (punch diameter currently down to 1 mm) in a multiaxial stress state.
Mechanical Properties:
Shear Punch Testing: Activation Volume
b
YS 650 MPa US 690 MPa
Initial shear punch relaxation tests show physical activation volumes for nanocrystalline Cu-Ta that are ~1 order of magnitude lower than conventional coarse-grained Cu samples (i.e., faster relaxation, but at much higher stresses).
Mechanical Properties:
Activation Volume vs Grain Size
Physical activation volume measured through stress relaxation agrees with values for pure Cu of similar grain size taken from literature. Ta precipitation does not appear to alter dislocation mechanisms governing plasticity. Darling, K.A., Tschopp, M.A., Kecskes, L.J., et al., Acta Materialia (2014).
J Chen, L, Lu and K. Lu Scripta Mat. 54 (2006) 1913
Mechanical Properties: Strain Rate Sensitivity
Strain Rate Sensitivity
3kT 3 3kT m v vH
Hardness values are 2X higher than pure Cu of similar grain size
H = hardness Activation volumes measured via instrumented indentation strain rate sensitivity experiments agree reasonable well with shear punch measured values Materials
Cu-10Ta-700
Cu-10Ta-900
Cu-1Ta-700
V*(b3)
17
30
23
Darling, K.A., Tschopp, M.A., Kecskes, L.J., et al., Acta Materialia (2014).
RJ Asaro, S Suresh Acta Mat. 53 (2005) 3369
Mechanical Properties: Strain Rate Sensitivity
Strain Rate Sensitivity, m, falls in line with previous results as a function of grain size.
Darling, K.A., Tschopp, M.A., Kecskes, L.J., et al., Acta Materialia (2014); Tschopp, M.A., Murdoch, H.A., Kecskes, L.J., Darling, K.A., JOM (2014).
Mechanical Properties: Hall-Petch plot
Tschopp, M.A., Murdoch, H.A., Kecskes, L.J., Darling, K.A., JOM (2014); Darling, K.A., Tschopp, M.A., et al., Acta Materialia (2014).
Mechanical Properties:
Quasi Static Room and High Temperature Compression
Room Temperature Quasi-Static Compression
High Temperature Quasi-Static Compression
• Strength values 2X higher than pure nanocrystalline Cu of similar GS
• Dramatic decrease in YS with increasing temperature
Mechanical Properties:
Quasi Static Room and High Temperature Compression
High Temperature Yield Stress vs Post-test RT Yield Stress
At Temperature YS Room Temperature YS Measured by taking the Hv/3 Post Testing Softening due to Thermal Energy Softening due to Microstructure Evolution
Softening is due to thermal effects and not microstructure evolution! (Notice that the strength of nc Cu-Ta at 1000 deg C is same as RT nano Cu)
ARL Expertise in Nanocrystalline Materials Material Processing:
Microstructure Control:
Properties:
Mechanical Alloying
Thermodynamic Stability
Mechanical Properties
Material Processing:
Powder Consolidation (ECAE Processing)
Thermal Stability
Bulk Consolidation
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Large Scale Power Production: Zoz Milling
Large scale mechanical alloying equipment was utilized for powder processing of large bulk objects • Different types of technology available • Processing times are relatively short • System is hermetically sealed • Semi-continuous scale up is possible • Can be done cryogenically
Large Scale Processing: Near Net Shaping
Pilot Scale Manufacturing Field Assisted Sintering (FAST) • Drastically reduced sintering times • Near net shaping possible
Hot Isostatic Pressing • Can produce large billets • Initial starting microstructure can be retained in consolidated bulk parts
World Class ARL facility visited by university, national laboratory and industry partners: Specializing in Rapid Development of New Materials
Large Scale Processing: Cu-Ta Dome
Fully Dense with nc structure! No visible porosity via SEM
Schematic of the HIP canister with SS tooling
Dome after machining out of the HIP can
Compare to nc Tantulum
2-3 times stronger Cu-1Ta 700 (168 nm)
Cu-10Ta 900 (213 nm)
Cu-10Ta 700 (70 nm)
NC Pure Cu (70 – 250 nm)
NC Ta (44 – 250 nm)
HV
2.12
2.12
3.75
1.35-1.0
4.1-2.5
HV/3
0.7
0.7
1.23
0.45-0.35
1.36-0.83
HV/6
0.35
0.35
0.62
0.23-0.18
0.68-0.42
0.45-0.35
1.3-0.9
SPT
σYS
0.43
0.45
0.69
QS
σYS
0.7
0.66
1.1
σ0.1
0.8
0.8
1.3
σ0.1
1.0
1.0
1.5
DY
1.6-0.95 0.88-0.55
2.0-1.2
Who would have thought that you can get the strength of nc Ta by adding 90% Cu?
Cu-10Ta 700 (70 nm)
NC Pure Cu (70 – 250 nm)
NC Ta (44 – 250 nm)
HV
2.12
2.12
3.75
1.35-1.0
4.1-2.5
HV/3
0.7
0.7
1.23
0.45-0.35
1.36-0.83
HV/6
0.35
0.35
0.62
0.23-0.18
0.68-0.42
0.45-0.35
1.3-0.9
σYS
0.43
0.45
0.69
QS
σYS
0.7
0.66
1.1
σ0.1
0.8
0.8
1.3
σ0.1
1.0
1.0
1.5
DY
1.6-0.95 0.88-0.55
2.0-1.2
100% Cu
SPT
Cu-10% Ta
Cu-10Ta 900 (213 nm)
Strength
Cu-1Ta 700 (168 nm)
100% Ta
Summary
Assumes same nanocrystalline grain size
% Ta Addition to Cu
ARL is STRENGTHENING and STABILIZING nc metals, enabling BULK nanocrystalline specimens to be a reality
Other Research Interests HCP mechanical behavior
crashworthiness & vehicle design
Bridging the gap between materials science & solid mechanics
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Other Research Interests L W S M MMSD M R B D
PE Deformation
Future Work / Working on: • 3D Characterization • VPSC - HCP metals • Small Scale Testing • Material Informatics • Neural Networks • nc Grain Boundaries • Mg Atomistic Modeling • First Principles / Mesoscale Models
Polymer Potential Development
Nanocrystalline Design Maps
3D Materials Science – Metal Foam
Thermokinetic Grain Growth Model
MEDE Metals Modeling CTRG
Lightweight & Specialty Metals Branch (LSMB)
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Other Research Interests Deformation in HCP metals
Army Interest in HCP and Magnesium
Twinning in FCC
Challenges for Magnesium
Generalized Framework for Shear and Shuffles
Twinning in HCP
Flat and Corrugated K 1
Discussion, Experiments, Implications, Conclusions
Collaboration with Haitham El Kadiri, Kip Barrett (MSU)
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Other Research Interests High Temperature Materials, 3D Materials Science
AFOSR funded, w/ AFRL (A. Rosenberger, J. Miller), MSU (A. Oppedal), and ASU (K. Solanki)
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Other Research Interests Scale Bridging / Understanding Interatomic Potentials
Tools That Can Help
Potential Design and Design Optimization Understanding Potentials and their Parameterization
Collaboration with S. Nouranian (Ole Miss), K. Solanki (ASU), and M. Baskes (MSU/LANL/UCSD)
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
Other Research Interests Integrated Computational Materials Engineering
How do we accelerate the materials discovery cycle and engineer transformational materials?
Statistical Sampling StructureProperty Database Data Reduction & Informatics
Metamodel Generation
PROCESSING
Design Optimization
Materials Design Sensitivity Analysis / Uncertainty Quantification
Optimal Alloy / Process
Virtual Experiments
STRUCTURE
PROPERTY
PERFORMANCE
Other Research Interests Grain Boundary (Segregation) Engineering
Atomistic and Mesoscale Modeling of Grain Boundaries: Exploiting Interfacial Structure-Property Relationships to Improve the Damage Tolerance of Boron Carbide and Boron Suboxide TASK 5
Expand time/length scales towards the mesoscale calculated
experiment TASK 4
Evaluate and develop interatomic potentials
TASK 3
Quantify, predict, and validate grain boundary properties
LEVERAGE INTERNAL PROGRAMS & MEDE B4C CMRG
Kleebe et al., 2008
V TASK 2
Characterize and validate grain boundary structures
B4C B6O
TASK 1
Develop and optimize grain boundary generation State of the Art, Art of the Possible!
Virtual Diffraction Techniques (LAMMPS)
PROCESSING
STRUCTURE
PROPERTY
PERFORMANCE
A L I D A T E W I T H
E X P E R I M E N T S
Any Questions?
Mark de’ Medici
Contact Info: Mark Tschopp, U.S. Army Research Lab
[email protected]