Atomistic Study of Irradiation-Induced Plastic and Lattice Strain in Tungsten

TL;DR

This study uses atomistic simulations to analyze how irradiation causes plastic deformation and lattice strain in tungsten, revealing dislocation dynamics and the emergence of plasticity at high doses.

Contribution

It introduces a novel method to decompose elasto-plastic deformation from atomistic data and links dislocation loop behavior to lattice strain changes in irradiated tungsten.

Findings

Dislocation loops initiate plastic strain in irradiated metals.

Plastic strain emerges at high irradiation doses, causing lattice swelling.

Plastic transformations are categorized into slip and slip with swelling.

Abstract

We demonstrate a practical way to perform decomposition of the elasto-plastic deformation directly from atomistic simulation snapshots. Through molecular dynamics simulations on a large single crystal, we elucidate the intricate process of converting plastic strain, atomic strain, and rigid rotation during irradiation. Our study highlights how prismatic dislocation loops act as initiators of plastic strain effects in heavily irradiated metals, resulting in experimentally measurable alterations in lattice strain. We show the onset of plastic strain starts to emerge at high dose, leading to the spontaneous emergence of dislocation creep and irradiation-induced lattice swelling. This phenomenon arises from the agglomeration of dislocation loops into a dislocation network. Furthermore, our numerical framework enables us to categorize the plastic transformation into two distinct types: pure slip events and slip events accompanied by lattice swelling. The latter type is particularly responsible for the observed divergence in interstitial and vacancy counts, and also impacts the behavior of dislocations, potentially activating non-conventional slip systems.