Systematic investigation of the deformation mechanisms of a {\gamma}-TiAl single crystal

TL;DR

This paper introduces a theoretical framework combining stacking fault energy and Schmid factor to predict deformation mechanisms in {}-TiAl single crystals, validated by molecular dynamics simulations and applicable to other ductile intermetallics.

Contribution

A novel theoretical approach predicting deformation mechanisms in {}-TiAl crystals without lattice defects, validated against simulations and experiments.

Findings

Accurately predicts slip, twinning, and fracture mechanisms.

Matches experimental results with few exceptions.

Method applicable to other ductile intermetallics.

Abstract

We propose a theoretical framework to predict the deformation mechanism of the {\gamma}-TiAl single crystal without lattice defects by combining the generalized stacking fault energy and the Schmid factor. Our theory is validated against an excellent testbed, the single crystal nanowire, by correctly predicting four major deformation mechanisms, namely, ordinary slip, super slip, twinning, and mixed slip/fracture observed during the tensile and compressive tests along 10 different orientations using molecular dynamics simulations. Interestingly, although lattice defects are not taken into account, the theoretical predictions match well with existing experiments on bulk specimen with only a few exceptions; the exceptions are discussed based on the size-dependent deformation mechanism in the presence of preexisting dislocation sources. We expect that the method in this paper can be generalized to study various ductile intermetallic crystals where conventional Schmid law does not hold well.