Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 15 No. 1 February 2005|
（1. Central Laboratory, Zhejiang University, Hangzhou 310028, China;
2. Chemical Engineering Department, Zhejiang University of Technology,
Hangzhou 310014, China）
Abstract:Evolution of microstructures of alloy MlNi3.75Co0.75Mn0.3Al0.2 (Ml—La-rich mischmetal) during the electrochemical hydriding-dehydriding process was studied by using in-situ X-ray diffraction method. It is indicated that both the crystallite sizes of α phase (solid solution phase) and β phase (hydride phase) decrease with the hydrogen content increasing during this process. β phase is found to be composed of the plate-like and the needle-like crystallites, while the crystallite size of the former changes more rapidly than that of the later during the hydriding-dehydriding process. It’s also clearly found that strains along (110) plane and (001) plane of α phase and β phase are higher in the α+β region than those in the corresponding single phase region. Based on the microstructural studies, mechanism for the hydride growth has also been proposed.
Key words: in-situ X-ray diffraction; crystallite size; hydrogen storage alloy; hydride