Microtextural investigation of hydrided α-uranium

The local orientation features in as-cast α-uranium were investigated in order to ascertain the influence of texture and heterogeneity in the microstructure on hydride initiation and growth. Several samples were interrogated via automated electron back-scattered diffraction measurements in the post-hydride state. Characterization included orientation mapping, deformation twin identification, and grain boundary analysis. It was found that preferential hydride initiation sites were associated with general high-angle grain boundaries, low-angle boundaries, and twin boundaries of two systems. Linear segregation or precipitation features suggest the existence of unresolved twins that could be correlated with many of the remaining hydrides. The tendency of certain orientations to exhibit differing hydride potentials based on atomic density in the habit plane was also considered. The results suggest the dominant role of enhanced sub-surface hydrogen diffusion at misoriented regions in controlling hydride nucleation and growth. [Copyright &y& Elsevier]