Alloying and Amorphization Processes in the Mechanical Alloying of Al-Ni-Zr Mixed Powder by Planetary Ball Mill

摘要

As its excellent mechanical and chemical properties, the formation processes of Al-Ni-Zr amorphous alloys, which was formed by mechanical alloying (MA) method, were investigated in this study. Planetary ball mill was used to carry out MA. Double mechanical alloying (DMA) method was also taken, where the binary amorphous alloys are first synthesized by MA from a elemental powder mixture and are further milled with the third elemental powder to form ternary amorphous alloys. On the first step, Ni-35 approx 40 mol percent Zr amorphous phases were formed at the rotation frequency of 250 rpm. Aluminum powder was added to the amorphous Ni-Zr powder after that, and Al-40 mol percent (Ni-40 mol percent Zr) could be obtained when the DMA was carried out at 200 rpm. In this case, however, the recovery ratio of milled powder would be under 20 percent of initial weight. Then 1 mass percent stearic acid was added and it was found to be effective to improve the yield of milled powders as well as the formation range of amorphous phase. Furthermore, the synthesized alloys by two types of ball mill were compared, and it was confirmed that when oscillatory ball mill was used for MA, Al-Ni-Zr amorphous alloys were formed over a wider range than that in the case of using planetary ball mill.