Preferred hydride growth orientation of U−0.79 wt.%Ti alloy with β+U2Ti microstructure

Abstract

The nucleation and propagation during the early stage of the hydriding of U–0.79wt.%Ti were investigated in order to ascertain the influence of texture and microstructure on hydride initiation and growth. Several samples of the so-called “β+U2Ti” microstructure were prepared in a specially designed manner. The topographical characteristics of the post-hydrided sample surface were collected via laser confocal microscope and Scanning Electron Microscope (SEM). Good correlation was found between the strip-type hydride and the underlying metal matrix. The discontinuities in the oxide layer and the differences in thickness, composition and structure of the oxide on α-U and U2Ti may influence the hydrogen diffusion through the oxide barrier. The difference of hydriding reaction tendency and durability against hydride powdering between α-phase and U2Ti were proposed to account for the anisotropic hydride growth, which resulted in the strip-type hydride. The results suggest that the metal properties, including microstructure, inclusions and affinity toward hydrogen, is the dominants of nucleation sites.