METALLURGICAL STATE OF LANTHANUM AND ITS EFFECTS ON THE ACTIVATION BEHAVIOR OF ZR(CR0.4NI0.6)(2) HYDRIDE FORMATION

Lanthanum was added to cubic C15 type Zr(Cr0.4Ni0.6)(2) to prepare Zr( Cr0.4Ni0.6)(2)La-0.05. Metallographical observation and microprobe ana lysis indicate that lanthanum does not dissolve in the Laves phase, bu t preferentially combines with nickel to form the LaNi phase which pre cipitates dispersively at the grain boundaries of the Laves phase toge ther with Zr7Ni10. It is found by X-ray diffraction that the cell para meters of the Laves phase before and after adding lanthanum are the sa me. However, Zr(Cr0.4Ni0.6)(2)La-0.05 shows much better activation beh aviour than Zr(Cr0.4Ni0.6)(2), both in solid-H-2 reaction and alkaline electrolyte, which is believed to result from the presence of the LaN i phase.