Atomistic and mean-field estimates of effective stiffness tensor of nanocrystalline materials of hexagonal symmetry

TL;DR

This paper extends an anisotropic core-shell model to estimate the effective elastic stiffness of nanocrystalline metals with hexagonal symmetry, validated by atomistic simulations and analyzing grain size effects.

Contribution

It introduces a mean-field model for nanocrystalline hexagonal metals that accounts for grain boundary and core properties, validated against atomistic simulations.

Findings

Model accurately predicts elastic moduli of nanocrystalline metals.

Grain size significantly influences overall elastic properties.

Validation confirms the model's applicability to real materials.

Abstract

Anisotropic core-shell model of a nano-grained polycrystal is extended to estimate the effective elastic stiffness of several metals of hexagonal crystal lattice symmetry. In the approach the bulk nanocrystalline material is described as a two-phase medium with different properties for a grain boundary zone and a grain core. While the grain core is anisotropic, the boundary zone is isotropic and has a thickness defined by the cutoff radius of a corresponding atomistic potential for the considered metal. The predictions of the proposed meanfield model are verified with respect to simulations performed with the use of the Large-scale Atomic/Molecular Massively Parallel Simulator, the Embedded Atom Model, and the molecular statics method. The effect of the grain size on the overall elastic moduli of nanocrystalline material with random distribution of orientations is analysed.