(西安交通大学 材料科学与工程学院 金属材料强度国家重点实验室， 西安 710049)
摘 要: 以La0.8Mg0.2Ni2.8Co0.6合金为基材， 采用感应熔炼法制得以Ce， Pr， Nd部分替代La的系列储氢合金。 3种稀土元素的加入对合金的组织没有本质的影响。 与La0.8Mg0.2Ni2.8Co0.6的相组成相似， 新合金也是在主相LaNi5中含有LaNi3第二相，且随着Ce，Pr，Nd替换量的增多， LaNi3相所占比例升高。 在La0.8-xRExMg0.2Ni2.8Co0.6合金中， 当Pr替换至x=0.2时， 新合金基本保持La0.8Mg0.2Ni2.8Co0.6的放电容量375mA·h/g； 其他添加比例及添加元素都在一定程度上降低了新合金的放电容量。加入Ce和Pr普遍提高放电电位， 而Nd对放电电位的影响不大。 La0.8Mg0.2Ni2.8Co0.6的容量衰减速率为1.07mA·h/(g·cycle)， 当Ce， Pr, Nd分别替换至x=0.3, 0.6, 0.6时， 新合金的容量衰减速率依次降低到0.566， 0.625, 0.453mA·h/(g·cycle)，循环稳定性有了很大提高。
关键字: 储氢合金； 放电容量； 循环稳定性； 稀土元素
La0.8Mg0.2Ni2.8Co0.6 hydrogen storage alloy
（State Key Laboratory for Mechanical Behavior of Materials,
School of Materials Scienceand Engineering,
Xi′an Jiaotong University, Xi′an 710049, China）
Abstract:A new series hydrogen storage alloys with elements Ce, Pr and Nd replacing La in alloy La0.8Mg0.2Ni2.8Co0.6 were obtained by electric induction melting. The addition of three rare earth elements has no significant influence on microstructures of the new alloys and the microstructures of new alloys are similar to that of La0.8Mg0.2Ni2.8Co0.6, LaNi5 phase with LaNi3 is as secondary phase; LaNi3 phase increases with the increases of amount of Ce, Pr, Nd. In La0.8-xRExMg0.2Ni2.8Co0.6 alloys the discharge capacities of the new alloys keep no change on 375mA·h/g, with only Pr addition to x=0.2; the other elements make the capacities decrease. The introduction of Ce, Pr makes the discharge voltage increases, while Nd shows less effect. Compared with the capacity decay rate of 1.07mA·h/(g·cycle) for the alloy La0.8Mg0.2Ni2.8Co0.6, the capacity decay rates of the new alloys are 0.566, 0.625 and 0.453mA·h/(g.cycle) with Ce, Pr and Nd addition to x=0.3, 0.6 and 0.6, respectively, which shows the stability of charging/discharging cycle is improved obviously.
Key words: hydrogen storage alloy; discharge capacity; cycle stability; rare earth element
