Grain growth beyond the Mullins model, capturing the complex physics behind universal grain size distributions

TL;DR

This paper uses advanced simulations to explore grain growth in metallic films, revealing complex physics behind universal grain size distributions that differ from classical models and capturing experimental features like the 'ear' and 'tail'.

Contribution

The study introduces large-scale phase field crystal simulations that accurately reproduce experimental grain size distributions and uncover the non-universality of the dynamic growth exponent.

Findings

Simulations match experimental grain size distributions, including 'ear' and 'tail' features.

Geometric and topological characteristics are universal, but the growth exponent is not.

The phase field crystal model effectively captures complex grain growth phenomena.

Abstract

Grain growth experiments on thin metallic films have shown the geometric and topological characteristics of the grain structure to be universal and independent of many experimental conditions. The universal size distribution, however, is found to differ both qualitatively and quantitatively from the standard Mullins curvature driven model of grain growth; with the experiments exhibiting an excess of small grains (termed an "ear") and an excess of very large grains (termed a "tail") compared with the model. While a plethora of extensions of the Mullins model have been proposed to explain these characteristics, none have been successful. In this work, large scale simulations of a model that resolves the atomic scale on diffusive time scales, the phase field crystal model, is used to examine the complex phenomena of grain growth. The results are in remarkable agreement with the experimental results, recovering the characteristic "ear" and "tail" features of the experimental grain size distribution. The simulations also indicate that while the geometric and topological characteristics are universal, the dynamic growth exponent is not.