Assessing size effects on the deformation of nanovoids in metallic materials

TL;DR

This study develops an experimental method to evaluate how nanovoids in metals deform under stress, revealing size-dependent effects mainly for voids smaller than 10 nm, and suggests a possible interface hardened layer influences deformation.

Contribution

It introduces a new experimental approach to assess size effects on nanovoids deformation and links findings to surface tension and interface properties through simulations.

Findings

No size effects for voids larger than 10 nm

Small size effects observed for voids smaller than 10 nm

Data compatible with a hardened interface layer

Abstract

An experimental methodology is developed to evaluate size effects in nanovoids deformation under macroscopic uniaxial stress loading conditions. Quantitative evaluation of voids deformation as a function of voids size shows both a crystallographic effect, albeit small compared to the scatter, and no evidence of size effects for voids diameter larger than 10 nm, while a slight effect is present for smaller voids. Critical assessment of the data in light of theoretical models indicates that these results may be compatible with the presence of a hardened layer at the void/matrix interface, which is illustrated through finite element simulations accounting for surface tension.