3 Johnson BMGs

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Published on January 10, 2008

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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 MPam 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

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