Studying the elastic properties of nanocrystalline copper using a model of randomly packed uniform grains

TL;DR

This study introduces a Voronoi-based method to create dense nanocrystalline copper models and uses molecular dynamics to measure elastic properties, revealing that grain boundaries are less stiff than grain interiors.

Contribution

A new Voronoi protocol for generating dense nanocrystalline copper models and detailed MD-based elastic property measurements at finite temperature.

Findings

Grain boundary deforms more locally than grain interior.

Grain boundary elastic modulus is less than 30% of grain interior.

Results support improved continuum modeling of nanocrystalline metals.

Abstract

We develop a new Voronoi protocol, which is a space tessellation method, to generate fully dense (containing no voids) nanocrystalline models of copper (Cu) with precise grain size control; we also perform uniaxial tensile tests using molecular dynamical (MD) simulations to measure the elastic moduli of the grain boundary and the grain interior components at 300 K. We find that the grain boundary deforms more locally compared with the grain core region under thermal vibrations and is elastically less stiff than the core component at finite temperature. The elastic modulus of the grain boundary is lower than 30% of that of the grain interior. Our results will aid in the development of more accurate continuum models of nanocrystalline metals.