Synthesis and structural characterization of mechanically alloyed AB3-type based material: LaZr2Mn4Ni5

In this study, a new AB3-type compound LaZr2Mn4Ni5 has been synthesized by mechanical alloying (MA) process starting from a mixture of two binary compounds LaNi5 (CaCu5-type structure, P6/mmm space group) and ZrMn2-Laves phase (MgZn2-type structure, P63/mmc space group) in order to take advantage of the hydrogen absorption properties of these two types of intermetallic compounds. X-ray diffraction (XRD), electron probe micro-analysis (EPMA) and transmission electron microscopy (TEM) were used to determine the structural properties and the phase evolution of the powder mixtures for different milling durations ranging from 5 to 25 h. The results show multiphase alloys which contain LaZr2Mn4Ni5 main phase with hexagonal PuNi3-type structure (R-3m space group). Rietveld analysis proves that both of La and Zr atoms are located in the two types of allowed sites 3a and 6c of the PuNi3-type structure. It is found that using a planetary ball mill, the maximum weight content (40 wt%) of LaZr2Mn4Ni5 compound was obtained at room temperature after 5 h of mechanical alloying.