Nucleation of Grain Boundary Phases

TL;DR

This paper develops a theoretical model for the homogeneous nucleation of grain boundary phases, incorporating elastic interactions and junction energies, and applies it to tungsten simulations to explain structural stability.

Contribution

It introduces a comprehensive theory accounting for junction energies and elastic forces in GB phase nucleation, advancing understanding of phase transformations.

Findings

The model predicts nucleation barriers based on junction and elastic energies.

Simulations in tungsten validate the theory's predictions.

The theory explains conditions preventing spontaneous GB phase changes.

Abstract

We derive a theory that describes homogeneous nucleation of grain boundary (GB) phases. Our analysis takes account of the energy resulting from the GB phase junction, the line defect separating two different GB structures, which is necessarily a dislocation as well as an elastic line force due to the jump in GB stresses. The theory provides analytic forms for the elastic interactions and the core energy of the GB phase junction that, along with the change in GB energy, determine the nucleation barrier. We apply the resulting nucleation model to simulations of GB phase transformations in tungsten. Our theory explains why under certain conditions GBs cannot spontaneously change their structure even to a lower energy state.