Atomistic investigation of elementary dislocation properties influencing mechanical behaviour of Cr15Fe46Mn17Ni22 alloy and Cr20Fe70Ni10 alloy

Abstract

In this work, molecular dynamics (MD) simulations were used to investigate elementary dislocation properties in a Co-free high entropy (HEA) model alloy (Cr15Fe46Mn17Ni22 at. %) in comparison with a model alloy representative of Austenitic Stainless Steel (ASS) (Cr20Fe70Ni10 at. %). Recently developed embedded-atom method (EAM) potentials were used to describe the atomic interactions in the alloys. Molecular Statics (MS) calculations were used to study the dislocation properties in terms of local stacking fault energy (SFE), dissociation distance while MD was used to investigate the dissociation distance under applied shear stress as a function of temperature and strain rate. It was shown that higher critical stress is required to move dislocations in the HEA alloy compared with the ASS model alloy. The theoretical investigation of simulation results of the dislocation mobility shows that a simple constitutive mobility law allows to predict dislocation velocity in both alloys over three orders of magnitude, covering the phonon drag regime and the thermally activated regime induced by dislocation unpinning from local hard configurations.