快淬纳米晶/非晶Mg2-xLaxNi (x=0~0.6)合金的电化学贮氢性能

用铸造及快淬工艺制备Mg2Ni型Mg2-xLaxNi(x=0,0.2,0.4,0.6)贮氢合金。用XRD、SEM、HRTEM分析铸态及快淬态合金的微观结构。结果发现,在快淬无La合金中没有出现非晶相,但快淬含La合金显示了以非晶相为主的结构。用DSC研究快淬合金的热稳定性,表明La的含量及快淬对非晶相的晶化温度影响很小。电化学测试结果表明,铸态合金的放电容量随La含量的增加而增加,快淬态合金的放电容量随La含量的变化有极大值。La替代Mg显著地提高了铸态及快淬态合金的循环稳定性。

Electrochemical Hydrogen Storage Characteristics of Spun Nanocrystalline/Amorphous Mg2-xLaxNi (x=0-0.6) Alloys

Mg2Ni-type Mg2-xLaxNi (x=0, 0.2, 0.4, 0.6) hydrogen storage alloys were prepared by casting and rapid quenching, respectively. The microstructures of the as-cast and quenched alloys were studied by XRD, SEM and HRTEM. Results show that no amorphous phase forms in the as-quenched La-free alloy, but the as-quenched alloys containing La hold a major amorphous phase. Thermal stability of the as-quenched alloys was studied by DSC, and the results show that La content and the quenching rate induce a negligible influence on the crystallization temperature of the amorphous phase. The electrochemical measurement shows that the discharge capacity of the as-cast alloys grows with the increase of La content, while the as-quenched alloys obtain the maximum discharge capacities with the variation of La content. The substitution of La for Mg markedly enhances the cycle stability of the as-cast and quenched alloys