A molecular dynamics study of path-dependent grain boundary properties in nanocrystals prepared using different methods

TL;DR

This study uses molecular dynamics simulations to explore how different preparation methods affect the properties of grain boundaries in nanocrystals, revealing some properties are path-dependent while others are not.

Contribution

It demonstrates the path-dependent nature of certain grain boundary properties in nanocrystals based on their formation method, advancing understanding of nanocrystalline material behavior.

Findings

Quenched nanocrystals have lower boundary energy and smaller free volume.

Some properties like Young's modulus are unaffected by preparation method.

Differences are linked to annealing twins in quenched samples.

Abstract

Grain boundaries are thermodynamically unstable. Hence, their properties should be path-dependent: grain boundaries in nanocrystals prepared using different methods might exhibit different properties. Using molecular dynamics simulations, we investigated grain boundaries of nanocrystals formed by quenching,solidification with pre-induced nucleation sites, and Voronoi tessellation. Some properties were found to be path depend: the quenched model has lower boundary energy per atom, smaller boundary excess free volume per atom, and slower grain growth than the Voronoi model. We surmise that these differences are attributed to the abundant annealing twins in the quenched model. On the other hand, other properties are path independent, such as Young's modulus, Poisson's ratio, and the ratio between grain boundary energy and boundary excess free volume. The results of this study further the understanding of the structural-property relationship of nanocrystals and provide guidance to future simulation-based studies of nanocrystalline materials.