快速凝固制备La2Mg0．9Ni7．5Co1．5Al0.1贮氢合金的相结构及电化学性能

采用感应熔铸＋退火处理及快速凝固方法制备了La2Mg0．9Ni7．5Co1．5Al0.1贮氢合金。系统研究了快速凝固对合金的相结构、微观组织及电化学性能的影响。XRD分析表明，随着冷却速率的增加，La2Mg0．9Ni7．5Co1．5Al0.1合金的相组成发生了明显变化。退火合金由αLa2Ni7主相（Ce2Ni7型结构）和少量LaNi3相（PuNi3型结构）组成。随着冷却速率的增加，合金中出现LaNi5相（CaCu5型结构）和LaMgNi4（MgCu4Sn型结构）相，且新相的相丰度增加，aLa2Ni7相和LaNi3相的丰度减少。EPMA分析表明，快速凝固方法制备的La2Mg0．9Ni7．5Co1．5Al0.1贮氢合金为柱状晶组织且晶粒细小。合金电极的电化学测试表明，冷却速率对合金的活化性能影响不大。随冷却速率的增加，合金的最大放电容量减少、高倍率放电性能下降。在较低的冷却速率下（5m／s），合金电极的循环稳定性改善不明显，而随着凝固速度的进一步增加（20m／s），合金电极表现出较好的循环稳定性。

Phase Structure and Electrochemical Properties of La-Mg-Ni System La2Mg0.9Ni7.5Co1.5Al0.1 Hydrogen Storage Alloys Prepared by Melt Spun

The hydrogen storage alloys were prepared using induction melting followed by heating treatment and melt spun. The effect of melt spun on the phase structure, microstructure and electrochemical properties of La2Mg0.9Ni7.5Co1.5Al0.1 was investigated systematically XRD analysis shows that the obvious change of the phase composition of the La2Mgo.gNi7.5Co1.5Al0.1 alloy took place with the increase of quenching rate. The annealed alloy consists of aLa2Ni7 main phase with Ce2Ni7 type structure and a little LaNi3 second phases with PuNi3 type structure. With the increase of quenching rate, the LaNis phase with CaCus type structure and LaMgNi4phase with MgCu4Sn type structure appear in the alloys, the content of the new phases increases but the content of aLa2Ni7 phase and LaNij phase decreases. EPMA analysis indicates that the La2Mg0.9Ni7.5Co1.5Al0.1 alloys prepared by melt spun have fine columnar crystal structure. The electrochemical measurement shows that the quenching rate has little effect on the activation property but the maximum discharge capacity and the high rate discharge ability decrease with the increase of quenching rate. It has a little improvement of the cyclic stability at the lower quenching rate as 5m/s, but the alloy electrode demonstrates better cyclic stability with the further increase of quenching rate as 20 m/s