中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 17 No. 4 August 2007 |
（1. Department of Functional Material Research,
Central Iron and Steel Research Institute, Beijing 100081, China;
2. School of Material and Metallurgy, Inner Mongolia University of Science and
Technology, Baotou 014010, China;
3. School of Materials Science and Engineering,
University of Science and Technology Beijing, Beijing 100083, China）
Abstract:The La0.7Mg0.3Ni2.55−xCo0.45Cux (x=0, 0.1, 0.2, 0.3, 0.4) electrode alloys were prepared by casting and rapid quenching. Ni in the alloy was partially substituted by Cu in order to improve the cycle stability of La-Mg-Ni system (PuNi3-type) hydrogen storage alloy. The effects of substituting Ni with Cu on the microstructures and cycle stability of the alloys were investigated in detail. The results obtained by XRD, SEM and TEM show that the substitution of Cu for Ni is favourable for the formation of an amorphous in the as-quenched alloy, and this leads to an obvious refinement of the as-quenched alloy grains and a growth of the lattice constants and cell volumes of the as-cast and quenched alloys. The results obtained by the electrochemical measurement indicate that the cycle stability of the alloys significantly rises with the incremental variety of Cu content. When Cu content changes from 0 to 0.4, the cycle lives of the as-cast and quenched (30 m/s) alloys are enhanced from 72 to 88 cycles and from 100 to 121 cycles, respectively.
Key words: La-Mg-Ni alloy; La0.7Mg0.3Ni2.55−x alloy; Ni; microstructures; cycle stability
