Defect dynamics and uniaxial tensile deformation of equi and non-equi-atomic configuration of multi-elemental alloys

Abstract

In this article, molecular dynamics and statics-based simulations were carried out to study the effect of equi-atomic and non-equi-atomic compositions of multi-elemental alloys on defect dynamics and tensile deformation. High and medium entropy alloy configurations were subjected to uni-axial tensile loading, and deformation governing mechanism was identified with the help of dislocation extraction algorithm and common neighbour analysis. Due to low or negative stacking fault energy, phase transformation from FCC to HCP in conjunction with solid solution hardening was identified as the governing mechanism for the plastic deformation in most of the multi-elemental alloys. Atomistic snapshots of simulation box containing deformed configurations of medium and high entropy alloys also show heterogenous nucleation, pinning of dislocations, cross channelling of twin boundaries. It was predicted that in alloys with higher Cr content twinning and stacking fault is prominent mode of deformation. Nudged elastic band algorithm was used to predict the vacancy migration energies in each of the atomistic configurations. The results presented in the article are in qualitatively in agreement with the experimental results, and higher fidelity simulations helps in developing better understanding about the plastic deformation in equi and non-equi-atomic composition of multi-elemental alloys.