Microstructural study of hydride formation in Zr-1Nb alloy

Abstract

Hydriding of Zr-1Nb alloy having a microstructure comprising equiaxed α grains and a uniform distribution of spherical particles of the α -phase has been carried out in this study. The specimens were hydrided by gaseous charging method to different hydrogen levels. The microstructures of hydrided samples were examined as a function of hydrogen content. The formation of δ -hydride in slow cooled specimens and formation of γ -hydride in rapidly cooled specimens has been studied with their morphology, habit plane and orientation relationship with the a matrix in view. The habit planes of either type of hydride phase has been determined and compared with those observed in other Zr-Nb alloys. The orientation relationship between the a matrix and the δ -hydride was found to be the following: (0 0 0 1)_α||(1^- 1 1^-)_δ and [112^-0]_α||110]_δ; . The orientation relationship between the α matrix and the γ -hydride was of the following type: (000 1)_α||(001)_ϒ and [12^-10]_α||[11^-0]_ϒ. The internal structure of both types of hydride has been examined. The effect of the presence of the spherical β-phase particles in the a matrix on the growth of the hydride plates has been investigated.