HEAT-TREATMENT EFFECTS OF V-BASED SOLID-SOLUTION ALLOY WITH TINI-BASED NETWORK STRUCTURE ON HYDROGEN STORAGE AND ELECTRODE PROPERTIES

Heat-treatment at 973-1473 K was conducted on a V3TiNi0.56 alloy which consisted of a V-based solid solution main phase for hydrogen storage and a TiNi-based secondary phase for electrochemical reaction. Heat-t reatment at 1073 K was found to improve the durability during electric al charge-discharge cycles in Ni-MH cells because the corrosive vanadi um content in the secondary phase was decreased by the heat-treatment. High-rate capability, however, was decreased by heat-treatment above 1273 K because of the increased grain size of the main phase and degra dation of the TiNi-based network structure of the secondary phase.