Damage nucleation from repeated dislocation absorption at a grain boundary

TL;DR

This study uses molecular dynamics simulations to investigate how repeated dislocation absorption at grain boundaries leads to damage nucleation, revealing the influence of atomic shuffling and strain rate on crack formation.

Contribution

It introduces a simulation methodology to analyze damage nucleation at grain boundaries, highlighting atomic shuffling and strain rate effects on crack initiation.

Findings

Slower strain rates lead to earlier crack nucleation.

Atomic shuffling at the boundary influences damage mode.

Crack nucleation can be preceded by dislocation emission.

Abstract

Damage nucleation from repeated dislocation absorption at a grain boundary is simulated with molecular dynamics. At the grain boundary-dislocation intersection site, atomic shuffling events determine how the free volume brought by the incoming dislocation is accommodated. This process in turn determines the crack nucleation mechanism, as well as the critical strain and number of dislocations that can be absorbed before cracking. Slower strain rates promote earlier crack nucleation and a damage nucleation mode where cracking is preceded by dislocation emission. The simulation methodology presented here can be used to probe other types of boundaries as well, although multiple thermodynamically equivalent starting configurations are required to quantify the damage resistance of a given grain boundary.