Microstructure of alloy MlNi_(3.75)Co_(0.75)Mn_(0.3)Al_(0.2) (Ml—La-rich mischmetal) during electrochemical hydriding-dehydriding process

摘要

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.