铸态及快淬态La2Mg（Ni0.85Co0.15）9Crx（x=0～0.2）电极合金的微观结构及电化学性能

摘要:

为了提高La-Mg-Ni系（PuNi3）型贮氢合金的电化学循环稳定性,在La2Mg（Ni0.85Co0.15）9合金中加入微量Cr,用铸造及快淬工艺制备了La2Mg（Ni0.85Co0.15）9Crx（x=0,0.1,0.2）贮氢合金.分析测试了铸态及快淬态合金的电化学性能及微观结构,研究了Cr对铸态及快淬态合金微观结构及电化学性能的影响.结果表明,铸态及快淬态合金具有多相结构,包括（La,Mg）Ni3相（PuNi3结构））,LaNi5相和一定量的LaNi2相.快淬对合金的相组成没有影响,但使合金的相丰度产生变化.Cr的加入提高了铸态及快淬态合金的循环稳定性,但使合金的容量下降.合金的循环寿命随淬速的增加而增加,铸态及快淬态合金均有优良的活化性能.

Abstract:

In order to improve the electrochemical cycle stability of La-Mg-Ni system (PuNi3-type) hydrogen storage alloy, a trace of Cr was added in the alloy. La2Mg(Ni0.85Co0.15)9Crx (x= 0, 0.1 and 0.2) hydrogen storage alloys were prepared by casting and rapid quenching. The electrochemical performances and microstructures of the as-cast and quenched alloys were determined and measured. The effects of Cr content and quenching rate on the microstructures and electrochemical properties of the alloys were investigated in detail. The obtained results show that the as-cast and quenched alloys are composed of the (La, Mg)Ni3 phase (PuNi3-type structure) and the LaNi5 phase as well as the LaNi2 phase. The rapid quenching does not have much influence on the phase compositions of the alloys, but changed the phase abundances of the alloys obviously. The addition of Cr enhances the cycle stability of the as-cast and quenched alloys, but decreases the discharge capacities of the alloys. The cycle lives of the alloys increase with the increase of the quenching rate. The as-cast and quenched alloys have an excellent activation performance.