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利用Miedema理论和几何模型计算了二元合金系La M ,Ni M和三元合金系LaNi5-xMx(M =Co ,Mn ,Al,Cr ,Fe,Cu)的生成焓。对二元合金系 ,计算结果与已有实验结果在xM ≥ 70 % (摩尔分数 )范围符合得较好 ;三元合金系计算结果表明 ,当分别添加合金组元Mn ,Co ,Cr,Fe和Cu时 ,LaNi5-xMx 的生成焓不同程度地增大 ,其中Cr ,Fe和Mn的影响较大 ,而添加Al时生成焓明显减小。讨论了生成焓对合金高温氢化时发生歧化反应的影响 ,合金的生成焓越大 ,越有利于歧化反应。
The formation enthalpies of La M, Ni M and LaNi5-xMx (M = Co, Mn, Al, Cr, Fe, Cu) of ternary alloys were calculated by Miedema theory and geometric model. For the binary alloy system, the calculated results are in good agreement with the existing experimental results in the range of xM ≥ 70% (molar fraction). The calculated results of the ternary alloy system show that when the alloy elements Mn, Co, Cr, Fe and Cu, the enthalpy of formation of LaNi5-xMx increased to some extent, among which Cr, Fe and Mn had a greater influence, while the enthalpy of formation decreased remarkably when Al was added. The effects of enthalpies of formation on the disproportionation reaction during high temperature hydrogenation of the alloy were discussed. The larger the enthalpy of formation, the more favorable to the disproportionation reaction.