INFLUENCE OF ANNEALING ON HYDROGENATION CHARACTERISTICS AND MICROSTRUCTURE OF LANI4.55AL0.45 ALLOY

The influence of annealing time and temperature on the plateau slope and microstructure of a hydrogen-absorbing LaNi4.55Al0.45 alloy was investigated. The homogenizing behaviour during annealing was also analysed to clarify the effects of annealing quantitatively. Electron probe microanalysis and X-ray powder diffraction analysis indicated that the plateau slope is caused mainly by the fluctuation of Al concentration in the dominant phase. The dependence of the homogenizing behaviour on the annealing conditions is reasonably explained with a non-steady-state Al diffusion model where A is distributed periodically.