Deformation Induced Microstructural Modification: Session III: Computational Studies of Deformation
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Shaping and Forming Committee
Program Organizers: Arun Devaraj, Pacific Northwest National Laboratory; Suveen Mathaudhu, Colorado School of Mines; Kester Clarke, Los Alamos National Laboratory; Bharat Gwalani, North Carolina State Universtiy; Daniel Coughlin, United States Steel Corp
Tuesday 8:30 AM
March 16, 2021
Room: RM 38
Location: TMS2021 Virtual
Session Chair: Peter Sushko, Pacific Northwest National Laboratory; Suveen Mathaudhu, University of California Riverside
8:30 AM Invited
Grain Boundary Segregation in Nanocrystalline Alloys: Multicomponent, Anisotropy, and Stress Effects: Malek Alkayyali1; Yasir Mahmood1; Josh Arrington1; Fadi Abdeljawad1; 1Clemson University
The ever-growing demand for advanced structural alloys with optimal properties underpins the need to fundamentally understand the many microstructural features affecting materials performance. Of particular interest is the interaction of elemental species with grain boundaries (GBs), as it greatly influences the thermal stability and mechanical behavior of these systems. In this talk, we will present our recent efforts, employing atomistic simulations and mesoscale models, to investigate the impact of GB solute segregation on GB migration in nanocrystalline (NC) alloys. Several mesoscale phase field studies will be presented highlighting the role of multi-elemental segregation and GB anisotropy effects in grain growth processes in NC alloys. Atomistic simulations of stress-driven migration of pure and doped GBs highlight the paramount role of solute drag in the thermal stability of NC alloys. On the whole, our results reveal a plethora of mesoscale dynamical processes that emerge when multicomponent and anisotropy effects are considered.
9:00 AM
Effect of Loading Path on Grain Misorientation Evolution in Polycrystalline Al under Large Deformation: Wenkai Fu1; Yulan Li1; Shenyang Hu1; Peter Sushko1; Suveen Mathaudhu2; 1Pacific Northwest National Laboratory; 2Pacific Northwest National Laboratory & University of California, Riverside
Predictive understanding of microstructure evolution during solid phase processing is crucial to optimize loading path that affects grain misorientation for desired material microstructures and properties. In this work, the crystal plasticity theory is employed to investigate inhomogeneous and anisotropic deformation in polycrystalline aluminium under linear reciprocating tribometric loads. Several tribometric loading paths with shear deformation gradient up to 30% were studied. The dislocation density and lattice misorientation were calculated, and their dependence on the loading path was analyzed. It is found that 1) local lattice rotation starts from the grain boundaries of grains with large Schmid factors, and propagates with increasing density of geometrically necessary dislocations, and 2) load paths (or applied strains) impact dislocation recovery and dislocation structures and, hence, affect lattice rotation and grain misorientation. We demonstrate how to utilize this information to calculate the driving force of grain refinement and to determine the orientation of recrystallized grains.
9:20 AM
A First Principles Criterion for Microstructure Evolution in Deformation Twinned FCC Materials: Matthew Daly1; Ritesh Jagatramka1; Junaid Ahmed1; 1University of Illinois at Chicago
The process of deformation twinning influences the flow behavior of FCC metals through two signature features – plasticity accommodation and dynamic crystal refinement. These dual features raise an interesting question: under which conditions do FCC materials nucleate or thicken deformation twins in response to plastic deformation? Nucleation-favored twinning causes a rapid segmentation of a microstructure, whereas thickening-favored twinning leads to a unit-step decrease in crystal size. Here, a first-principles criterion to evaluate the competition between nucleation and thickening of deformation twins in FCC materials is presented. This criterion is based on activation barriers retrieved from the generalized stacking fault energy landscapes of common FCC materials and is therefore free from phenomenological fitting. Microstructure parameters such as the twin density and dislocation mean free path can be readily accessed through this approach. Ongoing efforts to expand this criterion to predict microstructure evolution in concentrated FCC solid solutions are also overviewed.
9:40 AM Invited
Microstructure-based Modeling of Impact-Induced Plastic Deformation: Qi Tang1; Mostafa Hassani1; 1Cornell University
Extreme plastic deformation occurs in a variety of impact-based material processes from surface mechanical attrition to cold spray. The strain levels in these processes are in principle large enough to lead to grain refinement by plasticity alone, while the addition of adiabatic heat opens the door to possible local recrystallization at the impact site. Due to the complexity of these processes predictive frameworks that can capture metal hardening up to very large strains are indispensable for process optimization. Here we present a microstructure-based constitutive model combined with finite element to predict impact-induced microstructural evolution. We apply the framework to surface mechanical attrition and cold spray impacts and discuss the evolution of dislocation density and grain refinement in these processes.
10:10 AM
Molecular Dynamics Simulations of Defect Structure Evolution under Shear Deformation in Polycrystalline Al: Nanjun Chen1; Shenyang Hu1; Wahyu Setyawan1; Peter Sushko1; Suveen Mathaudhu2; 1Pacific Northwest National Laboratory; 2University of California, Riverside
Materials subjected to solid-phase processing (SPP) often accumulate tremendous energy stored in the form of stress, causing dramatic structure transformations. To guide SPP towards achieving desired microstructures and material properties, it is essential to understand deformation mechanism and defect structure formation. Here, large-scale molecular dynamics simulations are used to investigate defect structure evolution under shear deformation in polycrystalline Al. Effects of temperature, deformation rates, and roughness of contact interface are systematically simulated with consideration of interatomic potential impact. The results reveal that high energy dislocations including [1-10](001) and ½[1-1-2](1-11) are activated, which affects defect reactions and evolution. The inhomogeneous and anisotropic stress field leads to the formation of different slip bands and, hence, to different defect substructures. We analyze spatial correlations among defects, energy and lattice misorientation and discuss how they enable establishing relationships between substructure and energy, in turn, leading to understanding of deformation behavior and metastable structure formation.
10:30 AM
Modeling the Bonding and Structure of Non-metallic Inclusions within a Nickel Matrix during Forging: Brandon Mackey1; Thomas Siegmund1; Michael Sangid1; 1Purdue University
Forging of metallic materials requires both high temperatures and large plastic deformation. During this process, three-dimensional defects, such as non-metallic inclusions, are known to debond from the metallic matrix and break up, resulting in a linear array of smaller inclusions, known as stringers. The presence of stringers can be detrimental to the fatigue life of the final forged component, especially when present near the free surface. By performing process modeling, we aim to provide a contribution to the understanding of deformation and failure sequences leading to the formation of stringers. A finite element model combining both solid and cohesive zone elements is solved with ABAQUS/Explicit to simulate the debonding and break up of an alumina inclusion in a nickel matrix, under isothermal forging conditions. Forging temperature, deformation per pass, and strain rate are examined to determine processing parameters correlating to the least detrimental stringer geometry in relation to fatigue loading.