La-Mg-Ni基(PuNi3型)贮氢合金的微观结构与电化学性能

用铸造及快淬工艺制备了La Mg Ni 系(PuNi3 型)贮氢合金La2Mg(Ni0.85 Co0.15)9Bx(x=0、0.1、0.2),分析测试了铸态及快淬态合金的微观结构与电化学性能,研究了硼及快淬工艺对合金微观结构及电化学性能的影响。结果表明,铸态合金具有多相结构,主相包括(La, Mg)Ni3 相和LiNi5 相,残余相为一定量的LaNi2 相和微量的Ni2B相,经快淬处理后Ni2B相消失,并且其它相的相对量随淬速的变化而变化。硼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。不含硼合金的容量随淬速的增加而单调减小,含硼合金的容量随淬速变化有一个极大值。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。

Microstructure and electrochemical performances of the La-Mg-Ni based (PuNi3-type) hydrogen atorage alloys

The La-Mg-Ni based (PnNi_3-type) hydrogen storage alloys La_2Mg(Ni_(0.85)Co_(0.15))_9B_x(x=0, 0.1, 0.2) were prepared by casting and rapid quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were determined and measured. The effects of boron content and quenching rate on the microstructures and electrochemical properties of the alloys were investigated in detail. The results show that the as-cast and quenched alloys are composed of the (La, Mg)Ni_3 phase, the LaNi_5 phase and the LaNi_2 phase. A trace of the Ni_2B phase exists in the as-cast alloys containing boron, and after the as-cast alloys are quenched, the Ni_2B phase in the alloys nearly disappears. The relative amount of each phase in the alloys depends on the quenching rate. The addition of boron enhances the cycle stability of the as-cast and quenching alloys, but decreases the discharge capacity of the alloys. The capacity of the alloys without boron monotonously decreases with the increase of the quenching rate. In the case of the alloys containing boron, the capacities have a maximum value when varying the quenching rate. The cycle stability of the as-quenched alloys increases with increasing quenching rate. The activation performances of the as-cast and quenched alloys are excellent.