Structural phase transformations in metallic grain boundaries

TL;DR

This paper introduces a new simulation methodology that reveals multiple reversible phase transformations in metallic grain boundaries, enhancing understanding of defect absorption and radiation damage healing.

Contribution

The study presents a novel simulation approach enabling the observation of multiple grain boundary phases and their transformations, addressing previous methodological limitations.

Findings

Multiple grain boundary phases identified

Reversible phase transformations observed with temperature and defects

Potential mechanism for radiation damage healing proposed

Abstract

Structural transformations at interfaces are of profound fundamental interest as complex examples of phase transitions in low-dimensional systems. Despite decades of extensive research, no compelling evidence exists for structural transformations in high-angle grain boundaries in elemental systems. Here we show that the critical impediment to observations of such phase transformations in atomistic modeling has been rooted in inadequate simulation methodology. The proposed new methodology allows variations in atomic density inside the grain boundary and reveals multiple grain boundary phases with different atomic structures. Reversible first-order transformations between such phases are observed by varying temperature or injecting point defects into the boundary region. Due to the presence of multiple metastable phases, grain boundaries can absorb significant amounts of point defects created inside the material by processes such as irradiation. We propose a novel mechanism of radiation damage healing in metals which may guide further improvements in radiation resistance of metallic materials through grain boundary engineering.