纳米晶和非晶Mg20-xLaxNi10(x=0-6)贮氢合金的贮氢行为

用快淬技术制备了Mg2Ni型贮氢合金，合金的名义成分为Mg20-xLaxNi10 (x = 0, 2, 4, 6)。用XRD、SEM、HRTEM分析了合金的微观结构。发现不含La的快淬合金中没有非晶相，但含La快淬合金中显示以非晶相为主。当La含量x≤2时，铸态合金的主相为Mg2Ni相，但随着La含量的进一步增加，铸态合金的主相改变为(La,Mg)Ni3+LaMg3相。应用Sieverts设备研究了铸态及快淬态合金的吸放氢量及动力学，结果表明，x=2的合金吸放氢量及动力学随淬速的增加而增加，但对于x=6的合金，结果是相反的。电化学测试结果表明，x=2合金的放电容量随淬速的增加而增加，而对于x=6合金，结果也是相反的。快淬显著地提高了x=2, 6合金的循环稳定性

Hydrogen Storage Behaviours of Nanocrystalline and Amorphous Mg20-xLaxNi10(x=0-6) Hydrogen Storage Alloys

Mg2Ni-type hydrogen storage alloys with nominal composition Mg20-xLaxNi10 (x = 0, 2, 4, 6) were prepared by melt spinning. The microstructures of the alloys were studied by XRD, SEM and HRTEM. It is found that no amorphous phase formed in the as-spun La-free alloy, but the as-spun alloys containing La mainly held a major amorphous phase. When La content x≤2, the major phase in the as-cast alloys is Mg2Ni phase, but with the further increase of La content, the major phase of the as-cast alloys changes into (La,Mg)Ni3+LaMg3 phases. The hydrogen absorption and desorption kinetics of the as-cast and spun alloys were measured using an automatically controlled Sieverts apparatus, indicating that the hydrogen absorption and desorption capacity and the kinetics of the x=2 alloy clearly increase with rising of spinning rate, but a contrary result is obtained for x = 6 alloy. The electrochemical measurement shows that the discharge capacity of the x = 2 alloy grows with rising of spinning rate, but it is a completely contrary result for x = 6 alloy. The melt spinning significantly improves the cycle stability of the x = 2 and 6 alloys.