# An atomistic view of grain boundary diffusion

## TL;DR

This paper reviews recent atomistic simulations of grain boundary diffusion, highlighting mechanisms at different temperatures and drawing parallels with supercooled liquids, advancing understanding of atomic-scale diffusion processes.

## Contribution

It provides a comprehensive overview of atomistic simulation results and introduces new insights into diffusion mechanisms in grain boundaries at various temperatures.

## Key findings

- Diffusion at low temperatures involves point defect-mediated collective jumps.
- High-temperature diffusion resembles supercooled liquid behavior with collective atomic displacements.
- Diffusion mechanisms include string-like atomic group movements.

## Abstract

This paper presents an overview of recent computer simulations of grain boundary (GB) diffusion focusing on atomistic understanding of diffusion mechanisms. At low temperatures when GB structure is ordered, diffusion is mediated by point defects inducing collective jumps of several atoms forming a chain. At high temperatures when GB structure becomes highly disordered, the diffusion process can be analyzed by statistical methods developed earlier for supercooled liquids and glasses. Previous atomistic simulations reported in the literature as well as the new simulations presented in this paper reveal a close similarity between diffusion mechanisms in GBs and in supercooled liquids. GB diffusion at high temperatures is dominated by collective displacements of atomic groups (clusters), many of which have one-dimensional geometries similar to strings. The recent progress in this field motivates future extensions of atomistic simulations to diffusion in alloy GBs, particularly in glass-forming systems.