Abstract The phase component and abundance in Zr(Mn0.45-xNi0.55)2 (x=0.10-0.40)Laves phase hydrogen storage alloy were investigated by X-ray multiphase Rietveld analysis. The results of Rietveld analysis showed that all the alloys were composed of C15, C14 type Laves phase and the residual phases such as Zr9M11 and ZrM phase. Laves phase and Zr9M11 phase existed in the studied composition range, however, ZrM phase only appeared in the range of x=0.20-0.40. When x=0.05 - 0.15, the alloys consisted of C15, C14 and Zr9 M11 phase, in which the main phase was of C15 type. At x=0.20-0.40, the alloys consisted of C15, C14, Zr9 M11 and ZrM, in which the main phase was the mixture of C15 and C14 phase. The phase abundance of Zr9 M11 had a little variation in the whole range, however, that of ZrM phase showed a bigger fluctuation. The lattice parameters of each phase appeared in alloys showed a tendency to increase as V content increases. On the basis of the calculation of averaged numbers of outer electrons, the occurrence of Laves phase was found to have correlation with electron factors.
