Peak broadening in X-ray powder diffraction (XRD) profiles of LaNi5-based a
lloys after hydriding and dehydriding processes, was investigated in order
to clarify the relation between the formation of lattice strain and degrada
tion by the hydriding-dehydriding cycling.
The degree of peak broadening in XRD profiles was calculated by the Rietvel
d method and hydrogen capacity was evaluated from P-C isotherms for LaNi5 a
nd LaNi5-alphaMalpha (M: Mn, Fe, Cu, Al; alpha= 0.25, 0.5) after activation
and after 1000 hydriding-dehydriding cycles, It was found that an anisotro
pic peak broadening parameter expressing lattice strain after activation ha
s a linear relation with the decrease in hydrogen capacity. The above param
eter is a suitable indicator of the ease of degradation in LaNi5-based allo
ys. (C) 2000 International Association for Hydrogen Energy. Published by El
sevier Science Ltd. All rights reserved.