Grain Boundaries and Interfaces: Metastability, Disorder, and Non-Equilibrium Behavior: On-Demand Poster Session
Sponsored by: TMS Materials Processing and Manufacturing Division, TMS: Computational Materials Science and Engineering Committee, TMS: Chemistry and Physics of Materials Committee, TMS: Phase Transformations Committee
Program Organizers: Yue Fan, University of Michigan; Liang Qi, University of Michigan; Jeremy Mason, University of California, Davis; Garritt Tucker, Colorado School of Mines; Pascal Bellon, University of Illinois at Urbana-Champaign; Mitra Taheri, Johns Hopkins University; Eric Homer, Brigham Young University; Xiaofeng Qian, Texas A&M University
Monday 8:00 AM
March 14, 2022
Room: Mechanics & Structural Reliability
Location: On-Demand Poster Hall
Configurational Entropy of Amorphous Undoped and Doped ZrO₂ and SiO₂: Megan Owen1; Michael Rushton1; Antoine Claisse2; William Lee1; Simon Middleburgh1; 1Bangor University; 2Westinghouse Electric Sweden AB
Amorphous regions may form along grain boundaries due to dopant segregation, radiation damage, and temperature effects. However, their thermodynamic favourability is not well understood. Experimental work shows vibrational entropy in crystalline and glassy, Cu₅₀0Zr₅₀0 and Cu₄₆Zr₄₆Al₈, are similar, with differences observed in configurational entropy [1]. These differences may be key to understanding how and why amorphous regions form along grain boundaries in bulk crystalline materials. Undoped and doped, amorphous and crystalline, ZrO₂ and SiO₂ were investigated due to their presence in nuclear environments. Simulated melt-quench procedures were conducted, and Voronoi tessellations characterised the configurational entropy, relating configurational entropy to favourability of formation. This work aims to analyse the favourability of amorphous regions as a function of dopant concentration and temperature to aid understanding of amorphous material thermodynamics.[1] H. L. Smith et al., “Separating the configurational and vibrational entropy contributions in metallic glasses,” Nat. Phys., 2017, doi: 10.1038/NPHYS4142.
Effect of Effective Range of Precipitate on Final Grain Radius of Grain Growth Simulation Based on the Local Curvature Multi-vertex Model: Shota Morimoto1; Shuichi Nakamura1; 1Nippon Steel
The local curvature multi-vertex model is an effective model to describe grain growth under the existence of precipitates, which is also applied to some industrial materials. In the model, it is possible to evaluate the free energy changes with movements of grain boundaries by introducing the concept of effective range of a precipitate on the matrix, composed of precipitate radius rp and its effective length reff, and grain growth is simulated based on the evaluated free energy changes. In order to clarify roles of the effective range on grain growth, we investigate Rg: average grain radius in a final state of the simulations under various conditions of rp and reff. As a result, Rg is a function of a pinning parameter k(=reff/rp) that is the independent variable of the pinning criteria whether a grain boundary is pinned by a precipitate, and becomes larger with the increase of k.
Self-healing Mechanisms in Shape Memory Alloys: Molecular Dynamics Study: Ahmed Shaker1; Tarek Hatem1; Iman El-Mahallawi1; 1The British University in Egypt
Self-healing materials have been an interest for researchers for the past 15 years for their importance in increasing the lifespan of mechanical parts and structures. On the other hand, Shape Memory Alloys (SMAs) is a class of materials with unique behaviour (including superelasticity and high-damage tolerance) and that made it highly desirable for commercial applications. SMAs show a promising self-healing behaviour which will be the investigation in this paper. Using molecular dynamics simulations (using LAMMPS) the behaviour of SMAs (specifically NiTi) is investigated. A single crystal with a crack is modelled under both shear and compressive loadings at different temperatures, where the impact of self-healing mechanisms are explored. The simulations showed a relation between the temperature and the amount of shear and compression needed for self-healing. Also, the investigation shows a different behaviour around the phase transformation temperature of NiTi.