Abstract
Formation of hydride in the surface layer of nickel and Ni-(10, 30, 50 at%)Fe alloys cathodically charged with hydrogen has been investigated by means of X-ray analysis and transmission electron microscopy. It has been found that the nickel hydride, which is of the face-centered cubic structure with a lattice constant about 6% larger than that of nickel, is formed by dissolution of hydrogen into a nickel lattice, and plastic deformation is caused by the formation of the hydride. In Ni-(10, 30, 50 at%)Fe alloys, several kinds of hydride with fcc structure were formed in the surface layer. The hydrides in Ni-(0, 10, 30, 50 at%)Fe specimens were not stable in air at room temperature, and the lattice constants decreased as they decomposed gradually. Based on the concentration of hydrogen in the specimens calculated from the change in the lattice constant, the phase diagram of (Ni, Fe)-H system was obtained.
