New Insights on Stacking Fault Behavior in Twin Induced Plasticity from Meta-Atom Molecular Dynamics Simulations

TL;DR

This study uses meta-atom molecular dynamics simulations to reveal new insights into stacking fault behavior in twin induced plasticity, highlighting dislocation reactions and the role of stacking fault energy in deformation twinning.

Contribution

It provides novel understanding of stacking fault interactions and their dependence on stacking fault energy, advancing knowledge of twin-induced plasticity mechanisms.

Findings

Stacking fault interactions are dominated by spontaneous dislocation reactions.

Stacking fault energy influences the competition among fault, twinning partial, and trailing partial dislocation.

Deformation twins act as both dislocation barriers and storage sites, enhancing strength and ductility.

Abstract

There is growing interest in promoting deformation twinning for plasticity in advanced materials, as highly organized twin boundaries are beneficial to better strength-ductility combination in contrast to disordered grain boundaries. Twinning deformation typically involves the kinetics of stacking faults, its interaction with dislocations, and dislocation - twin boundary interactions. While the latter has been intensively investigated, the dynamics of stacking faults has been less known. In this work, we report several new insights on the stacking fault behavior in twin induced plasticity from our meta-atom molecular dynamics simulation: The stacking fault interactions are dominated by dislocation reactions taking place spontaneously, different from the proposed mechanism in literatures; The competition among generating a single stacking fault, a twinning partial and a trailing partial dislocation is dependent on a unique parameter, i.e. stacking fault energy, which in turn determines deformation twinning behaviors. The complex twin-slip and twin-dislocation interactions demonstrate the dual role of deformation twins as both dislocation barrier and storage, potentially contributing to the high strength and ductility of advanced materials like TWIP steels where deformation twinning dominated plasticity accounts for the superb strength-ductility combination.