Electrochemical performance of Sn-substituted, LaNi5-based rapidly solidified alloys

Sn-substituted, LaNi5-based rapidly solidified alloys with low Co content, La(1-x)A(x)Ni(4.25)Co(0.5)Sn(0.25)(A=La, Nd, Ce,and x=0.2),were prepared by melt-spinning. The microstructure of the as-spun alloys was observed with SERI and the element distribution of the as-spun and annealed alloys was an alyzed by EDX. It is found that the as-spun alloys had fine grains. However , there was Sn segregation in the grain boundaries of the as-spun alloys. X RD patterns show that for the as-spun alloys the lattice strain could be al leviated through vacuum annealing. The electrochemical performance of the a s-spun and heat-treated alloys was investigated. It is found that the Ce-co ntaining as-spun alloy had a cycle Life more than 300 cycles. After heat-tr eatment, the electrochemical performance of the Ce-free alloys could be fur ther improved, which is attributed to the alleviation of the lattice strain and the change of Sn distribution. (C) 1999 Elsevier Science S.A. All righ ts reserved.