Magnesium Technology: Computational Materials Engineering
Sponsored by: TMS Light Metals Division, TMS: Magnesium Committee
Program Organizers: Petra Maier, University of Applied Sciences Stralsund; Steven Barela, Terves, Inc; Victoria Miller, University of Florida; Neale Neelameggham, IND LLC

Thursday 2:00 PM
March 3, 2022
Room: 210A
Location: Anaheim Convention Center

Session Chair: Sean Agnew, University of Virginia; Christopher Barrett, Mississippi State University

2:00 PM  
First-principles Investigation of Early-stage Precipitation in Mg-Sn and Mg-Zn Alloys: Du Cheng1; Kang Wang1; Bi-Cheng Zhou1; 1University of Virginia
    Mg-Sn and Mg-Zn alloys exhibit strong age-hardening effect and have become promising bases for high-strength and low-cost Mg alloys. However, the stoichiometries, atomic structures, phase stabilities, and formation mechanisms of the various nanoscale precipitates and intermetallic compounds during the heat treatment in these systems remain unclear. Here we use a combined approach of first-principles calculations, cluster expansion, and Monte Carlo simulation to investigate the atomic structures and thermodynamic stabilities of the experimentally reported precipitates as well as orderings on the FCC and HCP lattices in Mg-Sn and Mg-Zn alloys. The morphologies and formation mechanisms of precipitates are further inferred from the constituent strain energy analysis. In addition to the structure and stability of commonly observed compounds, potential Guinier-Preston (GP) zones are identified from preferred HCP orderings. Metastable phase diagrams with GP zones are constructed with both chemical and strain energy contributions which could help design better age-hardened Mg alloys.

2:20 PM  
A Predictive Multisurface Approach to Damage Modeling in Mg Alloys: Vigneshwaran Radhakrishnan1; Amine Benzerga1; 1Texas A&M University
    Two independent developments of multi-surface plasticity are consistently combined towards developing a robust method for predictive modeling of ductile damage in Mg alloys. The first development concerns a two-surface, pressure-insensitive plasticity model to describe the mechanical behavior of damage-free materials. The two surfaces separately account for the primary deformation mechanisms of glide and twinning. The model captures the 3D plastic anisotropy and the tension-compression asymmetry as the behavior evolves during straining. The second development concerns the effective behavior of porous plastic materials. Two or more surfaces account for one mode of homogeneous yielding (void growth in triaxial tension) and one or more modes of inhomogeneous yielding (void coalescence in triaxial tension and void distortion under severe shear). The model captures failure by internal necking or by void-sheet coalescence quite well.

2:40 PM  
Phase Field Modeling of Deformation Twinning and Dislocation Slip Interaction in Polycrystalline Solids: Eric Ocegueda1; Kaushik Bhattacharya1; 1California Institute of Technology
    Mechanical twinning is a form of inelastic deformation in magnesium and other hexagonal close-packed (hcp) metals, which has a drastic effect on material behavior. Magnesium’s high strength to weight ratio has led to its interest in structural, automotive, and armor applications, requiring a comprehensive understanding of twinning’s effect on material response. Past studies have taken either a microscopic approach, through molecular dynamics, or a macroscopic approach, through simplified pseudo-slip. However, twins interact across the mesoscale, forming collectively across grains with complex local morphology propagating into bulk behavior. To this end, we propose a variational model where twinning is treated using a phase-field approach, while slip is considered using crystal plasticity. Lattice reorientation, twinning length-scale, and twin-slip interactions arise naturally through energy minimization. We present GPU accelerated simulations on polycrystalline solids and summarize the insights gained from these studies and the implications on the macroscale behavior of hcp materials.

3:00 PM  
PRISMS-plasticity: Recent Advancements for Simulating Deformation of Mg Alloys: Mohammadreza Yaghoobi1; Aaditya Lakshmanan1; Zhe Chen1; Duncan A. Greeley1; John E. Allison1; Veera Sundararaghavan1; 1University of Michigan
    An open-source parallel 3-D crystal plasticity finite element (CPFE) software package PRISMS-Plasticity is presented here as a part of an overarching PRISMS Center integrated framework. Highly efficient rate-independent and rate-dependent crystal plasticity algorithms are implemented. Additionally, a new twinning-detwinning mechanism is incorporated into the framework based on an integration point sensitive scheme to model Mg alloys. The integration of the software as a part of the PRISMS Center framework is demonstrated. This integration includes well-defined pipelines for use of PRISMS-Plasticity software with experimental characterization techniques such as electron backscatter diffraction (EBSD), Digital Image Analysis (DIC), and high-energy synchrotron X-ray diffraction (HEDM), where appropriate these pipelines use popular open source software packages DREAM.3D and Neper. In addition, integration of the PRISMS-Plasticity results with the PRISMS Center information repository, the Materials Commons, will be presented. The parallel performance of the software demonstrates that it scales exceptionally well for large problems running on hundreds of processors.