Effect of helium bubbles on the mobility of edge dislocations in copper

TL;DR

This study uses molecular dynamics simulations to explore how helium bubbles influence the movement of edge dislocations in copper, revealing pressure-dependent interaction mechanisms relevant for nuclear material durability.

Contribution

It provides new insights into how helium bubble pressure affects dislocation interactions, advancing understanding of deformation in helium-irradiated copper.

Findings

High-pressure bubbles weaken obstacle strength

Super-jog formation occurs at high bubble pressure

Transition in interaction mechanism confirmed by activation energies

Abstract

Helium bubbles can form in materials upon exposure to irradiation. It is well known that the presence of helium bubbles can cause changes in the mechanical behavior of materials. To improve the lifetime of nuclear components, it is important to understand deformation mechanisms in helium-containing materials. In this work, we investigate the interactions between edge dislocations and helium bubbles in copper using molecular dynamics (MD) simulations. We focus on the effect of helium bubble pressure (equivalently, the helium-to-vacancy ratio) on the obstacle strength of helium bubbles and their interaction with dislocations. Our simulations predict significant differences in the interaction mechanisms as a function of helium bubble pressure. Specifically, bubbles with high internal pressure are found to exhibit weaker obstacle strength as compared to low-pressure bubbles of the same size due to the formation of super-jogs in the dislocation. Activation energies and rate constants extracted from the MD data confirm this transition in mechanism and enable upscaling of these phenomena to higher length-scale models.