Amorphous intergranular films mitigate radiation damage in nanocrystalline Cu-Zr

TL;DR

This study demonstrates that amorphous intergranular films in nanocrystalline Cu-Zr alloys reduce radiation-induced defects and limit grain growth, thereby enhancing radiation tolerance.

Contribution

It introduces the use of amorphous intergranular films to improve radiation tolerance and grain stability in nanocrystalline metals.

Findings

Fewer and smaller defect clusters with amorphous films

Limited grain growth in films-containing alloys

Enhanced radiation tolerance observed

Abstract

Nanocrystalline metals are promising radiation tolerant materials due to their large interfacial volume fraction, but irradiation-induced grain growth can eventually degrade any improvement in radiation tolerance. Therefore, methods to limit grain growth and simultaneously improve the radiation tolerance of nanocrystalline metals are needed. Amorphous intergranular films are unique grain boundary structures that are predicted to have improved sink efficiencies due to their increased thickness and amorphous structure, while also improving grain size stability. In this study, ball milled nanocrystalline Cu-Zr alloys are heat treated to either have only ordered grain boundaries or to contain amorphous intergranular films distributed within the grain boundary network, and are then subjected to in situ transmission electron microscopy irradiation and ex situ irradiation. Differences in defect density and grain growth due to grain boundary complexion type are then investigated. When amorphous intergranular films are incorporated within the material, fewer and smaller defect clusters are observed while grain growth is also limited, leading to nanocrystalline alloys with improved radiation tolerance.