纳米压痕
材料科学
成核
位错
缩进
分子动力学
结晶学
应变硬化指数
冶金
复合材料
热力学
计算化学
化学
物理
作者
F.J. Domínguez-Gutiérrez,Aneta Ustrzycka,Qinqin Xu,René Alvarez-Donado,Stefanos Papanikolaou,Mikko J. Alava
标识
DOI:10.1088/1361-651x/ac9d54
摘要
Abstract Fe-based alloys with high chromium and nickel concentrations are very attractive for efficient energy production in extreme operating conditions. We perform molecular dynamics (MD) simulations of nanoindentation on fcc FeNiCr multicomponent materials. Equiatomic FeNi, Fe 55 Ni 19 Cr 26 , and Fe 74 Ni 8 Cr 18 are tested by using established interatomic potentials and similar conditions, for the elucidation of key dislocation nucleation mechanisms and interactions. Generally, we find that the presence of Cr in these alloys reduces the mobility of prismatic dislocation loops, and increases their area, regardless of crystallographic orientation. Dislocation nucleation and evolution is tracked during mechanical testing as a function of nanoindentation strain and Kocks–Mecking continuum modeling displays good agreement with MD findings. Furthermore, the analysis of geometrically necessary dislocations (GNDs) is consistent with the Ma–Clarke’s model at depths lower than 1.5 nm. The presence of Cr leads to a decrease of the GND density with respect to Cr-less FeNi samples, thus we find that Cr is critically responsible of increasing these alloys’ hardness. Post-indentation impression maps indicate that Ni–Fe–Cr compositions display strain localization and hardening due to high Cr concentration.
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