Texture growth characterization in rare earth hydrogen storage alloys

By using X-ray diffraction technique and electrochemical measurements, the texture growth and its effects on the electrochemical properties have been explored under various cooling rates in rare-earth hydrogen storage alloys. It was shown that: (1) the different texture growth characters were obtained in the rare earth hydrogen storage alloys with various compositions under conventional fast cooling and a columnar structure was formed so that the c-axis of the hexagonal structure was oriented parallel to the cooling plane and a higher capacity was attained; (2) the alloy prepared from rapid solidification exhibits a strong (0002) based pole texture in the surface of alloy sheet, i.e. c-axis texture. Its crytal growth character is consistent well with the alloy MmNi(3.5)Co(0.7)Al(0.8) which has a columnar structure with very high endurance, and low lattice strain was obtained under controlled conditions including high rate cooling in the casting process for obtaining a columnar structure.