IRG-2: Synthesis, Properties, and Modeling of Bulk Metallic Glass Materials W.L. Johnson (Team Lead) : IRG-2: Synthesis, Properties, and Modeling of Bulk Metallic Glass Materials W.L. Johnson (Team Lead)
Synthesis & Processing
E. Ustundag and W.L. Johnson (Mat. Sci., Caltech)
Mechanical Properties
G. Ravichandran, A.J. Rosakis, & D. Owen (Appl. Mech., Caltech),
R. Dauskardt (Mat. Sci., Stanford)
Simulation and Modeling
M. Ortiz (Appl. Mech., Caltech)
W.A. Goddard (Chemistry, Caltech)
Outline of Presentation : Outline of Presentation Overview of IRG - program components, intellectual themes, rationale for MRSEC funding
Related Projects (DARPA SAM), Industrial Interactions
Selected Examples/Highlights of Project
Production of Glassy Samples (casting)
Studies of Deformation & Flow Laws
Mechanical Testing vs. temperature, strain rate, failure modes
An in-situ study of shear bands
Free Volume Studies with Positron Annihilation etc.
Tempering of Metallic Glasses - Residual Stresses
Molecular Dynamics Simulations
Finite Element Modeling
Summary and Conclusions
CSEM -IRG-2 Overview : CSEM -IRG-2 Overview Simulation and Modeling
Goddard & Johnson-
(MD Simulation - Constitutive Laws, Deformation Mechansms)
Ortiz/Goddard/Johnson/ Ravichandran
(Finite Element Modeling)
Microstructure, Design and Optimization Mechanical Testing Validation of Models
Constitutive Laws
Dynamic Deformation & High Speed Diagnostics
Rosakis, Ravichandran, Ustundag, Dauskardt DARPA SAM CENTER
(initiated May 2001)
ARO, ARL, AFRL
INDUSTRIAL PARTNERS
Liquidmetal Technologies, Howmet, GM, Luxfer, MMM, Primex, + others Materials Development, Synthesis, Processing, and Characterization
Johnson, Ustundag
(Industrial Partners) Howmet & ATI) Interfaces A B C
MRSEC-IRG-2 & DARPA-CSAM Distinct but Mutually Leveraging and Complementary Projects : MRSEC-IRG-2 & DARPA-CSAM Distinct but Mutually Leveraging and Complementary Projects CCSAM is focused on Developing Specific Materials Systems according to “Challenge Problems”
CCSAM utilizes MRSEC Infrastructure - DARPA SAM specifically does not fund equipment & infrastructure)
Examples of MRSEC Infrastructure Utilization
Casting facility, Electron Microscopy, Mechanical Testing Laboratory, MRSEC computational facility
MRSEC IRG-2 stresses development of fundamental scientific underpinnings => critical input to CSAM
MRSEC IRG-2 has a strong simulation and modeling component => forms basis for modeling specific engineering problems in CCSAM (e.g. ballistic impact/pentrators , etc.)
Interdisciplinary “Team Efforts” : Interdisciplinary “Team Efforts” Mechanical Testing and Evaluation
=> Analytic Models
=>Comparison with MD Results
=>Develop 2nd Generation Models
=> Input to FEM Molecular Dynamics
=> Microscopic Flow Mechanicsm
=> Develop Flow Laws
=>Compare with MT&E
=>Input to FEM Finite Element Modeling
=>Building blocks -
Analystic Constitutive Laws
Modeling of Multiphase Structures
Prediction of Mechanical Properties
=> Input Materials Design Concepts
for S&P 2nd Generation Materials Materials Development
Synthesis & Processing =>
Provide Materials for MT&E
<=> Utilize Inputs from Modeling
<=> Designed Microstructures for
Mechanical Performance Experiment Theory and Modeling New Structural Engineering Materials
IRG-2 - A Unique Inter-disciplinary Approach to Development of New Engineering Materials - Rationale for MRSEC Funding : IRG-2 - A Unique Inter-disciplinary Approach to Development of New Engineering Materials - Rationale for MRSEC Funding Brings together Broad Intellectual Components:
A. Use of phase equilibria, thermodynamics, kinetics to synthesize and process novel glassy metals containing engineered microstructures
B. Use of “state of the art” mechanical testing to evaluate mechanical response of materials to:
quasistatic loading, dynamic loading, fatigue and failure etc.
C. Use molecular dynamics (MD) and finite element modeling (FEM) to:
understand microscopic deformation and flow mechanisms using MD and mesoscopic MULTI-LENGTH-SCALE modeling of shear banding and crack physics with MD+FEM, + incorporate this knowledge into macroscopic models of mechanical behavior through FEM.
D. Iterative use of A+B+C for optimization of materials for engineering
Slide7 : Vitreloy
Alloys Copper Alloys Steel Titanium Alloys Aluminum Alloys Window Glass Useful Engineering Properties - Specific Strength
IRG-2 Over-riding Intellectual Themes Example - Length Scales in Processing, Microstructure and Mechanics : IRG-2 Over-riding Intellectual Themes Example - Length Scales in Processing, Microstructure and Mechanics
Slide9 : Exemplary scaling relations for Mechanical Properties of some SAM composites Predicting Properties => Testing => Modeling =>Materials Development => Microstructure Control of s and d Energy Absorption (to failure) ~ y global ~ 0.02Y (s/d)
example - Charpy or Izod impact energy
Fracture Toughness ~ [y p]1/2 ~ [0.02 Y(s/d)]1/2
Notice that these scale typically with a power of “1/d”
If t d => global participation in plasticity, then we get (s/d) ~ 1
For a Vitreloy Composite, => Potential Properties
Charpy ~ 200-400 Joules!
K1c ~ 120 MPa-m1/2 Very Tough Materials ! s = shear band width
d = shear band spacing
IRG-2 Industrial Outreach - Collaborations : IRG-2 Industrial Outreach - Collaborations Amorphous Technologies Primex Corp. Head Sports Inc. General Motors
Net Shape Forming MMM Micro-Replication Ordinance Army Research Labs
Examples of Technology Transfer & Commercial Product Development : Examples of Technology Transfer & Commercial Product Development Caltech MRSEC Liquidmetal Technologies
Sports Products
Defense Applications/Composites
Thermoplastic Forming Howmet - Howmet Metal Mould
Commercial High Pressure Vacuum
Injection Casting (Drs. N. Paton & G. Woelter) Alloy Development => Commercial Castings Patent Licenses Technology Transfer Cross Licensing
Partnering Agreements
Commercial Parts (golf) Army Research Lab
Ballistic Testing, L. Magness
ARDEC
System Integration Prototypes (ordinance)
Computer Modeling, Test Results ARO/SBIR Phase II
Larger Numbers of Protoypes
Commercial Scale UP Primex/General Dynamics
System Engineering Insertion into
Systems
Development of “Super-Vitreloy” a beta-phase BMG-matrix composite- A successful collaboration with Howmet : Development of “Super-Vitreloy” a beta-phase BMG-matrix composite- A successful collaboration with Howmet In-situ Beta-Phase Reinforced Composite
developed at Caltech - Johnson group Howmet
Develop Commercial Processing
(40 lbs.)
High Pressure Die Casting into
2’ x 2.5’ x1/8” plates
Fatigue Testing Mechanical Testing
Caltech - Ravichandran
Stanford - Dauskardt Plates for testing Alloy formulation to Howmet
Plates to Caltech for characterization Microstructure/Mechanical
Properties Correlation Commercial Material
for Components
Industrial Collaborations and Technology Transfer Activities : Industrial Collaborations and Technology Transfer Activities Processing/Manufacturing
Liquidmetal Technologies, US
technology transfer interface
product development
partnering agreements with suppliers and end users
Howmet Corporation, US
Alloying and Casting Technology
Commercial Component Manuafacturing
Process Technology Development
Kaitech & Dongyang LTD, Korea
casting equipment
thermoplastic processing
End Use - Products
General Motors (Automotive)
Head Sports & Liquidmetal Golf (Sports)
MMM (Replication Technology)
General Dynamics/Primex & ARL/ARDEC (Ordinance)
Boeing, Northrup Grummund, (Aircraft Components) - to be developed
Goal - Commercialization of Bulk Metallic Glass for Engineering Applications
Providing High Quality Test Specimens - A Requirement for Mechanical Testing & Evaluation - MRSEC Role : Providing High Quality Test Specimens - A Requirement for Mechanical Testing & Evaluation - MRSEC Role A Key Research Problem!
The Study of Mechanical Properties Requires
Fabrication of High Quality Test Specimens
of New Materials in the Form of Plates, Rods, Etc.
Development of a “Scaled Up”
Laboratory Facility Required
Solution => New Caltech Casting Facility
(collaboration with Dongyang LTD, Korea)
enabled by MRSEC Infrastructure!
Caltech High Pressure Injection Casting Machine for large Metallic Glass Castings => Tested 9/01-10/01 (Korea) - Set up at Caltech completed12/01 - Now near-operational : Caltech High Pressure Injection Casting Machine for large Metallic Glass Castings => Tested 9/01-10/01 (Korea) - Set up at Caltech completed12/01 - Now near-operational
Metallic glass plates cast with MRSEC casting system Plates are used for mechanical testing testing project [P. Kim, W. Johnson, with Kaitech & Dongyang groups] : Metallic glass plates cast with MRSEC casting system Plates are used for mechanical testing testing project [P. Kim, W. Johnson, with Kaitech & Dongyang groups] Copper Mold Amorphous Castings
Flat Plate
Tiered Plate High Quality Specimen for most mechanical testing
can produce in 1 mm thickness!
Internal Stresses in Bulk Metallic Glasses - Tempering (E. Ustundag, Clausen, Lee - collaboration with Johnson group members, Yim, ) : Internal Stresses in Bulk Metallic Glasses - Tempering (E. Ustundag, Clausen, Lee - collaboration with Johnson group members, Yim, ) THERMAL TEMPERING OF BMGs
Generation of compressive residual stresses on specimen surfaces balanced by tension in the middle.
Results from the viscoelastic nature of BMGs and the fast cooling used in their processing.
Significant stresses can be generated this way, e.g., ~500-700 MPa on plate surfaces.
For the first time, we modeled these stresses using an analytical calculation*.
Preliminary measurements confirm model predictions.
* C.C. Aydiner, E. Ustundag and J.C. Hanan, Metall. Mater. Trans., vol. 32A (2001), in print. Tempering Stress Profile Across Thickness of a Plate*
(as a function of Biot number, Bi = hk/l) Center Surface Compression Tension Cast Plate
Slide18 : “ Phase” / BMG Composites: Elastic and Plastic Anisotropy - In-situ Loading & Neutron Scattering Ustundag, Clausen, Lee, in collaboration with Kim, Choi-Yim, etc. E. Ustundag and co-workers Sample M1 (as cast) Sample M2 (heat treated) Single peak fits: large difference in elastic anisotropy (spread between reflections).
AI (M1) = 5.5, AI (M2) = 1.6.
Slide19 : Positron Annihilation Results Plastic strain increases free volume
Hydrogen charging decreases free volume Dauskardt et. al., Stanford
Slide20 : Positrons Annihilate Preferentially near Zr and Ti Momentum Spectrum Elemental Contributions Zr and Ti have disproportionately large contribution
Free volume not evenly distributed
Straining increases Zr contribution ~2%
Chemical reordering associated with strain
Slide21 : Free Volume and Flow (free volume creation/annihilation) Dauskardt, Flores, et. al. , Stanford
Mechanical Testing at Variable Strain Rates and Temperatures (Lu, Ravichandran, Dauskardt, Johnson, etc.)) -> Deformation Maps : Mechanical Testing at Variable Strain Rates and Temperatures (Lu, Ravichandran, Dauskardt, Johnson, etc.)) -> Deformation Maps Dynamic Strain Rate of 250 per s
variable T Deformation Maps Vary T
fixed strain rate Fixed T
Vary strain rate
From Homogeneous to Inhomogeneous Flow - Vitreloy 1 Lu, Ravichandran, Johnson, Bossuyt => Input to Modeling => Input to Casting & Processing : From Homogeneous to Inhomogeneous Flow - Vitreloy 1 Lu, Ravichandran, Johnson, Bossuyt => Input to Modeling => Input to Casting & Processing An experimental “Flow” Map
Shear Localization - Analytic Approaches : Shear Localization - Analytic Approaches Impose Constant Strain Rate dx/dt L = (1/L)dx/dt = constant
= G el
Overall strain rate fixed
Carry out linear stability analysis of the steady state flow state
Competition between strain softening (free volume creation), strain rate softening (non-Newtonian effect), and thermal heating effect -> dT/dt
Shear Band
Implementation of the Models - A hierarchy of flow conditions Mechanical Testing <=> Modeling =>Validation of Models : Implementation of the Models - A hierarchy of flow conditions Mechanical Testing <=> Modeling =>Validation of Models I. Newtonian Flow governed by empirical Vogel-Fulcher Law
homogeneous, steady state, II.Non-Newtonian Homogeneous and Steady State
steady state, homogeneous, finite III. Non-Newtonian Transient & Homogeneous
homogeneous, time dependent, finite IV. Non-Newtonian Inhomogeneous and Transient
inhomogeneous, time dependent, finite
=> shear banding
Slide26 : Analytic Constitutive Models for Deformation, Flow, and Heat (Lu et. al.)
Mechanical Testing (Ravichandran & Rosakis) => Modeling (Ortiz & Goddard)
Ductile Phase Toughened Bulk Metallic Glass Composites : Ductile Phase Toughened Bulk Metallic Glass Composites Tensile Bar Pulled to Failure. BMG-composite containing ductile dendrites
TEM - In-situ Imaging of Shear Bands in Composite : TEM - In-situ Imaging of Shear Bands in Composite Evgenia Pekerskaya & W.L. Johnson
J. Mater. Res., in press (2001) Composite Microstructure Shear Bands in Monolithic Glass
In-situ Deformation TEM images of Shear Band Propagation in Beta-Phase Composite (Pekerskaya & Johnson, 2001) A collaboration with Univ. of Illinois TEM Center : In-situ Deformation TEM images of Shear Band Propagation in Beta-Phase Composite (Pekerskaya & Johnson, 2001) A collaboration with Univ. of Illinois TEM Center Shear Bands Propogating in composite - observed directly during deformation
80% Tungsten Reinforced Bulk Metallic Composite : 80% Tungsten Reinforced Bulk Metallic Composite Flow Stress Dependence on strain and strain rate - Deformation Behavior
Slide32 : HIGH-SPEED CGS INTERFEROGRAMS OF GROWING MODE-I OPENING CRACKS (Rosakis and Owen) straight curving branching Cracks tip locations Field-of-view = 50 mm diameter
Cracks propagating from bottom to top corresponding
to different loading conditions Pre-cracks locations
Slide33 : Crack Tip Speeds (v/cs) DYNAMIC TOUGHNESS AND CRACK TIP SPEEDS (Rosakis, Owen, et. al.) Loading rate (MPa m1/2 s-1) Dynamic toughness versus
loading rate
Slide34 : DT (K)
1500
750
0 Field of View 1.3 mm square t = 10 ms t = 22 ms t = 34 ms TEMPERATURE RISE ACROSS A PROPAGATING SHEAR BAND During an Asymmetric Impact experiment - Rosakis, Owen, etc. High Speed Infrared Imaging (1 million frames per sec.) Room Temp. > 1500 C Velocity Asymmetric Impact Experiment
Plasticity Induced Heating - Mode II Infrared Imaging of Moving Crack Tip - (Dauskardt group) : Plasticity Induced Heating - Mode II Infrared Imaging of Moving Crack Tip - (Dauskardt group) Stable
KII = 77.3 MPam
Tmax = 0.55 K t = 0 t = 5 ms t = 10 ms Camera Parameters:
64 x 64 pixel array
30 mm pixels, 1000 Hz Temperature Change (K) Crack Growth Direction
The Role of Multi-scale Modeling : The Role of Multi-scale Modeling Understand the fundamental processes that govern the mechanical behavior of BMGs
- Multiscale simulations of deformation, flow laws, failure in BMGs + thermophysical properties of the glass/liquid
Provide microstructure-properties relationshipsfrom modeling
Provide guidelines for the development of processable BMG-based materials with improved properties (high strength density, stiffness, fracture toughness, impact resistance, fatigue resistance, etc.) A Collaboration among Goddard, Ortiz, Dauskardt, Ravichandran, & Johnson Groups
Multi scale modeling: new strategies for BMGs with enhanced plasticity and toughness : Multi scale modeling: new strategies for BMGs with enhanced plasticity and toughness Molecular Dynamics, Mesoscopic,
Finite Element Modeling
MD simulations of deformation in Amorphous Metals : Localized plastic deformation (shear at ~45 º) MD simulations of deformation in Amorphous Metals N=1370 atoms
strain rate = 0.5% / 10 ps
T = 300 K Uniaxial tension MD simulations Amorphous (Cu-Cu*) nano-wire We developed an algorithm to find groups of atoms that moved collectively
Shear Bands in Finite Element Models of BMG + Penetrator Impact Model (DARPA-SAM) Mota, Ortiz, in collaboration with Ravichandrun, Lu, Johnson, .. : Shear Bands in Finite Element Models of BMG + Penetrator Impact Model (DARPA-SAM) Mota, Ortiz, in collaboration with Ravichandrun, Lu, Johnson, .. Finite Element Simulation
of Penetrator Impact on Plate Shear Band Formation in Monolithic Glass
Summary : Summary