A computational alloy design framework for the promotion of amorphous grain boundary complexions

TL;DR

This paper introduces a computational framework using density functional theory to identify dopants that promote amorphous grain boundary complexions in alloys, aiding faster alloy design.

Contribution

The framework enables systematic selection of dopants for amorphous complexions, validated with W alloys and complex concentrated alloys, advancing alloy microstructure engineering.

Findings

Y and transition metals like Co and Ni lower energetic barriers for amorphization.

The framework correlates well with experimental sintering temperatures.

Electronic and charge analyses explain dopant effectiveness.

Abstract

Amorphous grain boundary complexions have been shown to be radiation tolerant interfaces that can also reduce grain boundary embrittlement, marking them as favorable microstructural features. However, the incorporation of these features into new alloy systems is often a slow and arduous process based on trial and error. Here, a computational framework for alloy design is presented which enables the selection of dopants that promote the formation of amorphous grain boundary complexions. This framework is primarily built on density functional theory calculations and is demonstrated for W-rich binary and ternary alloys, which represent a promising target for fusion energy materials. Our framework first evaluates the grain boundary segregation tendency of dopants and then the energy penalty for amorphization alongside targeted interfacial energy comparison, with the end goal of identifying the best dopants. For a W base, Y and some transition metals such as Co and Ni are found to significantly lower these energetic barriers. Electronic structure analysis, local lattice distortion, and charge density distributions are calculated and used to provide mechanistic explanations for these dopant selections. Finally, the framework is validated by comparing with experimental literature for W alloys and a refractory complex concentrated alloy, showing a strong correlation between our dopant selections and low sintering onset temperatures that have been attributed to activated sintering. As a whole, this work establishes a transferable pipeline for designing alloys with grain-boundary complexions across diverse alloy systems.