Materials Design Approaches and Experiences V: Light Metals
Sponsored by: TMS Structural Materials Division, TMS: High Temperature Alloys Committee, TMS: Integrated Computational Materials Engineering Committee
Program Organizers: Akane Suzuki, GE Aerospace Research; Ji-Cheng Zhao, University of Maryland; Michael Fahrmann, Haynes International; Qiang Feng, University of Science and Technology Beijing; Michael Titus, Purdue University
Wednesday 2:00 PM
February 26, 2020
Room: 33A
Location: San Diego Convention Ctr
Session Chair: Amit Shyam, Oak Ridge National Laboratory; Michael Titus, Purdue University
2:00 PM Invited
Microstructural Design for Advanced Aluminium and Magnesium Alloys: Jian-Feng Nie1; 1Monash University
Precipitation hardened aluminium and magnesium alloys often contain plate-shaped precipitates of intermediate or equilibrium phases that form on rational planes of the matrix phase. While it is commonly accepted that a higher number density of such precipitates is critical for achieving higher strength, the potential effect of the shape of such precipitates on strengthening is still not widely recognized. Micro-alloying additions can change the shape and/or distribution of these precipitate plates, but the precise roles of the micro-alloying elements in the formation of such precipitate plates are again a subject of debate. In this talk, the latest understanding of such issues will be presented. The emphasis will be placed on the formation mechanism of the precipitate plates, solute segregation at precipitate-matrix interfaces and planar defects, and the development of strengthening models that account for the real particle shape.
2:30 PM
Strength Prediction in a Quaternary Mg Alloy System Using a Multi-scale Optimization Framework: Stephen DeWitt1; Brian Puchala1; Qianying Shi1; Anirudh Raju Natarajan2; Chaoming Yang1; Anton Van der Ven2; Liang Qi1; John Allison1; 1University of Michigan; 2University of California, Santa Barbara
When developing a multi-scale model for a material property, many of the steps performed are similar regardless of specific material property or system. These steps can be loosely classified as steps fitting existing data (e.g. with machine learning), steps deciding where new data should be collected, steps linking model components with each other or with data repositories, and steps deploying the multi-scale model (e.g. optimization, inverse parameter estimation, uncertainty quantification). We have created a new open-source Python package, called prisms.multiscale, that performs these common operations. Here, we describe the use of prisms.multiscale for strength prediction in a quaternary Mg alloy system. This optimization problem involves the integration of first-principles statistical mechanics calculations (CASM), a thermodynamic database (ThermoCalc), KWN simulations (TC-PRISMA), dislocation dynamics simulations (ParaDiS), and a solute strengthening database. We demonstrate the effects of alloy composition and aging time on the alloy strength and validate the predictions against experiments.
2:50 PM Cancelled
Titanium Alloy and Process Design: Gaining Insights Through Multi-scale Computation and Comparison with Experiments: Yang Rui1; 1Institute of Metal Research Ca
Titanium alloys possess a rich variety of phase transformations and multi-scale microstructures, and computing and simulation at different scales can play significant roles in composition design, microstructure optimisation and property improvement. This talk will review work conducted in the past few years using such an experiment plus computation approach, taking examples from near-alpha titanium alloys and titanium aluminides for aero engine applications and from beta-type titanium alloys for biomedical and marine use. Such an integrated approach accelerates the optmisation process and in many cases sheds new light on unresolved problems. The topics to be covered include alloying effects on the alpha phase and their relations to creep resistance and cold dwell fatigue propensity, alloying effects, phase stability and deformation mechanisms of high strength titanium aluminides, and metastable phases and stress induced transformations in beta-type titanium alloys.
3:20 PM Break
3:40 PM Invited
On the Use of Multiscale Modeling Strategies to Design Precipitation-hardened Al Alloys: Sha Liu1; Ioannis Papadimitriou1; Bárbara Bellón2; Hong Liu3; Gustavo Esteban-Manzanares1; Rodrigo Santos-Güemes2; Javier Llorca2; 1IMDEA Materials Institute; 2IMDEA Materials Institute & Technical University of Madrid; 3Katholieke Universiteit Leuven
Design of precipitation hardened Al-Cu alloys is carried out by means of multiscale modelling strategies based on three different types of simulation cascades. The first one includes the determination of the Al-rich part of the Al-Cu phase diagram from first principles calculations and cluster expansion. The second multiscale strategy is aimed at predicting the homogeneous and heterogeneous nucleation and growth of precipitates during high temperature ageing from the Al-Cu phase diagram and first-principles calculations. Precipitate nucleation is estimated from classical nucleation theory while precipitate growth is determined using the phase-field model. Finally, molecular dynamics simulations in combination with the transition state theory is used to determine the strengthening of small precipitates while discrete dislocation dynamics is used to examine the interaction of dislocations with large precipitate. The simulation results are validated by comparison with experiments, showing the potential of the multiscale modelling approaches yo design Al alloys
4:10 PM
Non-equilibrium Interfacial Solute Segregation as a Thermal Stabilization Mechanism in Al-Cu Alloys: Amit Shyam1; Dongwon Shin1; Jonathan Poplawsky1; James Morris2; Patrick Shower3; Lawrence Allard1; Matthew Chisholm1; Thomas Watkins1; Sumit Bahl1; Allen Haynes1; 1Oak Ridge National Laboratory; 2Ames Laboratory; 3GE Global Research
In this presentation, we identify a non-equilibrium interfacial solute segregation (NEISS) mechanism in Al-Cu alloy microstructures that imparts increased thermal stability of the metastable θʹ phase over the thermodynamically stable θ phase. The NEISS mechanism can be implemented in Al-Cu alloy microstructures through microalloying elements that have diffusion coefficients lower than Cu, and that have a driving force for segregating to critical interfaces between the θʹ and the matrix. Through examples from the Al-Cu-Mn-Zr (ACMZ) alloy system, where θʹ precipitates are stable up to 350oC, it will be demonstrated that the NEISS mechanism effectively improves the thermal stability of θʹ precipitates. It will be further demonstrated that density functional theory calculations are a useful tool to identify elements that possess a thermodynamic driving force to segregate to the critical interfaces. It will be shown that this mechanism can be applied to progressively stabilize or “rejuvenate” precipitation hardened alloy systems.