Ion-beam radiation-induced Eshelby transformations: The mean and variance in hydrostatic and shear residual stresses

Ion beam plays a pivotal role in ion implantations and the fabrication of nanostructures. However, there lacks a quantitative model to describe the residual stresses associated with the ion-beam radiation. Radiation-induced residual stress/transformation strain have been mostly recognized in the hydrostatic sub strain space. Here, we use molecular dynamics (MD) simulations to show that the response of a material to irradiation is generally anisotropic that depends on the ion-beam direction, and should be described using tensorial quantities. We demonstrate that accelerator-based ion beam irradiation, combined with the intrinsic lattice anisotropy and externally induced anisotropy (such as anisotropic mechanical loadings), causes radiation-actuated shear transformation strains in addition to hydrostatic expansion. We map out these complex correlations for several materials. Radiation-induced defects are shown to be responsible for residual shear stresses in the manner of Eshelby inclusion transformation. We propose such tensorial response model should be considered for accurate nanoscale fabrication using ion-beam irradiation.(c) 2023 Elsevier Ltd. All rights reserved.

Automated summary

Ion beam plays a crucial role in ion implantation and nanostructure fabrication. However, the quantitative model for describing the residual stresses induced by ion-beam radiation is lacking. In this study, molecular dynamics simulations are used to demonstrate that the material response to irradiation is generally anisotropic and should be described using tensorial quantities. We show that accelerator-based ion beam irradiation, combined with intrinsic and externally induced anisotropy, causes shear transformation strains in addition to hydrostatic expansion, and we propose that this tensorial response model should be considered for accurate nanoscale fabrication using ion-beam irradiation.