Dislocation nucleation mechanisms during nanoindentation of concentrated FeNiCr alloys: unveiling the effects of Cr through molecular simulations

F. J. Dominguez-Gutierrez*, A. Ustrzycka, Q. Q. Xu, R. Alvarez-Donado, S. Papanikolaou, M. J. Alava

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)
66 Downloads (Pure)

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, Fe55Ni19Cr26, and Fe74Ni8Cr18 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.

Original languageEnglish
Article number085010
JournalModelling and Simulation in Materials Science and Engineering
Volume30
Issue number8
DOIs
Publication statusPublished - Dec 2022
MoE publication typeA1 Journal article-refereed

Keywords

  • continuum model
  • dislocation dynamics
  • MD simulations
  • nanoindentation
  • Ni alloys
  • Plasticity

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