(西安交通大學 材料科學與工程學院 金屬材料強度國家重點實驗室， 西安 710049)
摘 要: 以La0.8Mg0.2Ni2.8Co0.6合金為基材， 采用感應熔煉法制得以Ce， Pr， Nd部分替代La的系列儲氫合金。 3種稀土元素的加入對合金的組織沒有本質(zhì)的影響。 與La0.8Mg0.2Ni2.8Co0.6的相組成相似， 新合金也是在主相LaNi5中含有LaNi3第二相，且隨著Ce，Pr，Nd替換量的增多， LaNi3相所占比例升高。 在La0.8-xRExMg0.2Ni2.8Co0.6合金中， 當Pr替換至x=0.2時， 新合金基本保持La0.8Mg0.2Ni2.8Co0.6的放電容量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電容量。加入Ce和Pr普遍提高放電電位， 而Nd對放電電位的影響不大。 La0.8Mg0.2Ni2.8Co0.6的容量衰減速率為1.07mA·h/(g·cycle)， 當Ce， Pr, Nd分別替換至x=0.3, 0.6, 0.6時， 新合金的容量衰減速率依次降低到0.566， 0.625, 0.453mA·h/(g·cycle)，循環(huán)穩(wěn)定性有了很大提高。
關鍵字: 儲氫合金； 放電容量； 循環(huán)穩(wěn)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
