Texture and Anisotropy by Formation and Decomposition of NickelHydride

The effect of microstructure and crystal direction on the extent of phase transformation (EPT) of Ni into β-NiH by cathodic charging with H has been investigated by X-ray diffraction, EPT is controlled by the crystal direction in the case of heat-treated specimens. In the case of electrodeposited specimens, the imperfections of which are commensurate with those of cold-worked metals, EPT is controlled by both the crystal direction and the “dislocation-induced” anisotropy at the same time. The decomposition of β-NiH follows the Kolmogorov–Avrami–Johnson–Mehl kinetics. The microstructural anisotropy induces anisotropy in the rate of decomposition of β-NiH.