Microstructural characteristics, atomic-scale features, and growth mechanisms of deuterides (hydrides) in hafnium

TL;DR

This study investigates the microstructure, chemistry, and growth mechanisms of deuteride-hafnium interfaces using advanced microscopy techniques, providing insights relevant for nuclear material design and performance.

Contribution

It offers detailed atomic-scale characterization of deuteride-matrix interfaces in hafnium, revealing crystallographic relationships, dislocation structures, and segregation phenomena.

Findings

Crystallographic orientation relationships identified

Dislocation distributions at interfaces characterized

Oxygen segregation during deuteride growth observed

Abstract

Hafnium hydride is a promising material for next-generation nuclear reactors, particularly as control rods for fast fission and shielding in fusion systems. The material's intrinsic brittleness encourages its use in the form of hydride-metal composites, where the functional and mechanical performance is strongly influenced by the multiscale structure of hydride-matrix interfaces. In this study, we employ a suite of microscopy techniques, including scanning electron microscopy with electron backscatter diffraction, transmission electron microscopy with electron energy-loss spectroscopy, and atom probe tomography, to investigate the deuteride-matrix interfaces in a deuterium-charged Hf alloy. We characterise their structure and chemistry, extracting key information including the deuteride-matrix crystallographic orientation relationship, microstructural features, misfit-induced dislocation distributions, electron energy-loss characteristics, and the segregation of oxygen during deuteride growth. These findings help clarify the mechanisms of interface evolution and may contribute to improved understanding of hydride-metal systems, with potential relevance for their processing, performance, and design in nuclear applications.