Void-induced cross slip of screw dislocations in fcc copper

TL;DR

This study uses molecular dynamics to explore how voids influence screw dislocation movement in fcc copper, revealing temperature-dependent depinning mechanisms including cross slip and prismatic loop formation.

Contribution

It uncovers new depinning mechanisms involving multiple glide planes and void surface interactions, advancing understanding of dislocation behavior at different temperatures.

Findings

Depinning stress increases with complex mechanisms at higher temperatures.

Cross slip occurs on void surfaces above 300 K, enabling multi-plane dislocation motion.

Intrinsic prismatic loop formation is observed during depinning.

Abstract

Pinning interaction between a screw dislocation and a void in fcc copper is investigated by means of molecular dynamics simulation. A screw dislocation bows out to undergo depinning on the original glide plane at low temperatures, where the behavior of the depinning stress is consistent with that obtained by a continuum model. If the temperature is higher than 300 K, the motion of a screw dislocation is no longer restricted to a single glide plane due to cross slip on the void surface. Several depinning mechanisms that involve multiple glide planes are found. In particular, a depinning mechanism that produces an intrinsic prismatic loop is found. We show that these complex depinning mechanisms significantly increase the depinning stress.