Investigation On Forming Law And Mechanism Of Ternary Alloy In The Course Of Solid-Liquid Reaction Ball Milling

It is a hot topic to prepare a variety of alloy powders by means of reaction milling in powder metallurgy nowadays. But most of these available studies are focused on solid-gas ,solid-solid reaction. In this thesis, the principle and applications of mechanical alloying and mechanochemistry technologies were reviewed. By means of the novel solid-liquid reaction milling technique, the phase evolution rules of the ternary alloy systems Al-Cu-Co and Al-Cu-Ni were investigated systematically on the basis of those of binary alloys. Furthermore, the solid-liquid reaction principle and the mechanism of ternary alloys was discussed on the basis of the experimental results and the fundamentals of physical-chemistry reaction. The results are shown as following:(1) For the ternary alloy Al-Cu-Co system, the Al-Cu binary alloy melt and pure Cu ball were selected as the starting materials and the milling medium respectively. The Al65Co15Cu20 and Al69Co25Cu6 ternary alloy powders were generated after milling melt Al-33.2wt%Cu for12h at 923K or 973K, and 24h at 923K or 1023K. When the Al-54wt%Cu(Al2Cu) alloy melt was selected as the starting material, the Al65Cu15Cu20 powders were obtained when milling by 12h at 893K or 24h at 993K. The Al65Cu15Co20 powders were generated by milling Al-70wt%(AlCu) alloy melt with Cuballs for 24h at 1123K. All the obtained Al-Cu-Co intermetallics powders were nanopartials.(2) For the Al-Cu-Ni ternaty alloy system, Ni ball and molten Al-Cu binary alloy were selected as the starting materials and the milling medium. The Al7CU4Ni powders were prepared by milling for 12h or 24h at 893K with the molten Al-33.2wt%Cu alloy melt as the starting materials. The Al7Cu4Ni, Al0.28Cuo.69Ni0- powders were obtained by milling molten Al-54wt%(Al2Cu) for 12h at 893K, 24h at 993K. The Al0.28Cu0.69Ni0- powders were fabricated by milling molten Al-70wt%Cu(AlCu) alloy for 24h at 1123K.The size of the obtained Al-Cu-Ni intermetallics powders is about 150nm.(3) The formation process of the ternary intermetallic powder and its contentdepended on the compositiont of the molten binary alloy which severed as the starting material. The atom ratio of the ternary alloy was close to that of the binary alloy. The higher milling temperature and the longer milling time are favorable to the formation of the ternary alloy powders. The third solid component of the ternary alloy powders increased with the milling time.The reaction model of ternary alloy solid-liquid reaction technique was developed on the basis of the collision-peeling model. Basing on the mechanochemistry theory, the mechanism of solid-liquid reaction was brought forward, which described the solid-liquid reaction process in three aspects such as the effect of the mechanical force on powders and the molten metal, the effect of solid-liquid diffusion and the effect of the newly-formed fresh surface.