Molecular dynamics simulation of Ga penetration along Al grain boundaries under a constant strain rate condition

TL;DR

This study uses molecular dynamics simulations to investigate how liquid gallium penetrates aluminum grain boundaries under constant strain, revealing dislocation mechanisms that contribute to embrittlement.

Contribution

It provides detailed atomic-level insights into Ga penetration along Al grain boundaries and identifies dislocation behaviors during the process, which were previously not well understood.

Findings

Dislocation nucleation at grain boundary groove tips

Dislocation climb along the grain boundary during Ga penetration

Atomic structure characterization of dislocations

Abstract

While diverse fracture characteristics have been observed in liquid metal embrittlement (LME) depending on the solid-liquid metal pairs, the penetration of nanometer-thick liquid metal films along the grain boundary has been identified as one of the key mechanisms for embrittlement in many classical LME systems, such as Al-Ga, Cu-Bi and Ni-Bi. For example, liquid Ga quickly penetrates deep into grain boundaries in Al, leading to intergranular fracture under very small stresses. We report on a series of molecular dynamics simulations of liquid Ga in contact with an Al bicrystal under a constant strain rate. We identify the grain boundary dislocations that are nucleated at the grain boundary groove tip and climb down along the grain boundary during Ga penetration and characterize their atomic structures based on topological method.