A synchrotron X-ray diffraction study of strain and microstrain distributions in α-Zr caused by hydride precipitation

A thin zirconium hydride layer was deposited electrolytically on a hot-rolled and annealed Zr-2.5 wt.% Nb material. Changes in the alpha-Zr phase associated with the hydride precipitation were studied by synchrotron X-ray diffraction. Strain variations and the dislocation density in the alpha-Zr matrix were estimated from changes in diffraction peak positions and using X-ray Line Profile Analysis, respectively. It was shown that the dislocation density increased measurably in the alpha-Zr matrix due to the precipitation of the hydrides which corroborates previous transmission electron microscopy (TEM) observations indicating that the alpha-Zr accommodates some of the volume misfit by plastic deformation. The probable strain profile in the Zr-H system as a function of tested layer thickness is discussed.