Generalized stacking fault energetics and dislocation properties: compact vs. spread unit dislocation structures in TiAl and CuAu

TL;DR

This paper introduces a unified scheme combining ab-initio calculations and the Peierls-Nabarro model to analyze dislocation structures and mobility in TiAl and CuAu, revealing core dissociation paths and differences in dislocation properties.

Contribution

It develops a general, ab-initio-based approach to study dislocation structures and energetics, linking core configurations with stacking fault energetics in TiAl and CuAu.

Findings

Differences in dislocation core structures are related to $\gamma$-surface features.

Unified description of compact, spread, and split dislocation cores.

Identification of dissociation paths in dislocation cores.

Abstract

We present a general scheme for analyzing the structure and mobility of dislocations based on solutions of the Peierls-Nabarro model with a two component displacement field and restoring forces determined from the ab-initio generalized stacking fault energetics (ie., the so-called $\gamma$-surface). The approach is used to investigate dislocations in L1$_{0}$ TiAl and CuAu; predicted differences in the unit dislocation properties are explicitly related with features of the $\gamma$-surface geometry. A unified description of compact, spread and split dislocation cores is provided with an important characteristic "dissociation path" revealed by this highly tractable scheme.