硼及快淬工艺对La-Mg-Ni系贮氢合金的微观结构及电化学容量的影响

Effects of boron additive and rapid quenching technique on the microstructrue and electrochemical capacity of La-Mg-Ni system hydrogen storage alloy

用铸造及快淬工艺制备了La-Mg-Ni系(PuNi3型)贮氢合金La2Mg(Ni0.85Co0.15)9Bx(x=0,0.05,0.1,0.15,0.2),分析测试了铸态及快淬态合金的微观结构与电化学容量,研究了硼及快淬工艺对合金微观结构及电化学容量的影响.结果表明,铸态合金具有多相结构,包括(La,Mg)Ni3相(PuNi3型)、LaNi5相,一定量的LaNi2相和微量的Ni2B相,经快淬处理后Ni2B相消失.硼的加入对铸态及快淬态合金的容量产生不同的影响,铸态合金的容量随硼含量的增加而单调下降,而快淬态合金的容量随硼含量的增加有一极大值.快淬处理对含硼及不含硼合金的容量也有不同的影响,随淬速的增加,不含硼合金的容量单调下降,而含硼合金的容量可以获得一个极大值.

La-Mg-Ni system （PuNi3-type） La2Mg（Ni0.85Co0.15）9 Bx（x = 0,0.05,0.1,0.15,0.2） hydrogen storage alloys were prepared by casting and rapid quenching. The microstructures and electrochemical capacities of the as-cast and quenched alloys were determined and measured. The effects of the boron content and the quenching rate on the microstructures and electrochemical capacities of the alloys were investigated in detail. The obtained results show that the as-cast and quenched alloys have a multi-phase structure, composing of the （La, Mg） Ni3 phase （PuNi3 structure）, the LaNi5 phase and the LaNi2 phase. A trace of the Ni2B phase exists in the as-cast alloys containing boron. The Ni2B phase in the alloys containing boron nearly disappears after rapid quenching. The effects of boron addition on the capacities of the as-cast and quenched alloys are different. The capacities of the as-cast alloys monotonously decrease with the increase in boron content, whereas the capacities of the as-quenched alloys have a maximum value with the change of boron content. The effects of rapid quenching on the capacities of the alloys with boron and without boron are different. The capacity of the alloy without boron monotonously decreases with increasing the quenching rate, whereas the capacities of the alloys with boron have a maximum value with the change of the quenching rate.