Pinning of dislocations in disordered alloys: Effects of dislocation orientation

TL;DR

This paper investigates how dislocation orientation affects pinning in disordered alloys, revealing anisotropic stress correlations and multiple pinning minima, especially near screw orientations.

Contribution

It introduces an analytical framework for understanding dislocation pinning considering anisotropic long-range stress correlations in complex alloys.

Findings

Edge dislocations follow standard pinning behavior.

Near screw dislocations exhibit two types of pinning energy minima.

Stress correlations are anisotropic with long-range tails.

Abstract

The current interest in compositionally complex alloys including so called high entropy alloys has caused renewed interest in the general problem of solute hardening. It has been suggested that this problem can be addressed by treating the alloy as an effective medium containing a random distribution of dilatation and compression centers representing the volumetric misfit of atoms of different species. The mean square stresses arising from such a random distribution can be calculated analytically, their spatial correlations are strongly anisotropic and exhibit long-range tails with third-order power law decay. Here we discuss implications of the anisotropic and long-range nature of the correlation functions for the pinning of dislocations of arbitrary orientation. While edge dislocations are found to follow the standard pinning paradigm, for dislocations of near screw orientation we demonstrate the co-existence of two types of pinning energy minima.