Electrolytic Synthesis Of LaNi_5-xCu_x（x=0-2）Powders And In Situ Heat Treatment In The Molten Salt

FFC Cambridge process, a new technique which has a short route, low energy consumption and no environmental influence is proposed for preparation of LaNi5powders by direct electrolytic deoxidization NiO-La2O3. The reduction pathway from the mixture of NiO-La2O3to LaNi5was studied by examination of partially and fully reduced samples using XRD and SEM with EDS analyses. The results indicates that first stage of the reaction involved the rapid reduction of NiO to form Ni, there after La2O3was electrochemically reduced and alloyed with Ni to form LaNi5.Based on these results, a series of LaNi5-xCux(x=0.5,1,1.5,2)alloys were prepared by FFC Cambridge process. The effects of substituting Ni with Cu on the phase structure and morphology on the alloys were investigated in detail. X-ray diffraction(XRD) indicates that the alloys consist of a single LaNi5phase with a hexagonal CaCu5structure and the bulk phase structure of the alloy is not changed by the partial substitution of Ni for Cu. The parameters a, c, and the cell volume(V) increase with increasing contents.The reason of this phenomenon is discussed.The effect of heat treatment on the structure and of LaNi4.5CU0.5hydrogen storage alloy has been studied systematically. The results show that the alloys still consist of the CaCus-type single phase and the lattice parameters and cell volumes of the phases are all increased with prolongation of treating time. The agglomeration of the samples are significantly improved and the particle size become more and more uniform with increasing treating time. We can tell that the crystal defects reduced,residual stress released and the composition homogenization owing to the heat treatment.