Preparation of Nanocrystalline Ti-6Al-4V Alloy by Mechanical Alloying

Ti-6Al-4V alloy powder was prepared by mechanical alloying. The alloying mechanism and the relationship of alloyed products to processes were investigated. The results show that mechanical alloying can prepare nanocrystalline Ti-6Al-4V alloy powder. The reaction mechanism is dominated by diffusion, and the solid-state reaction is the interaction result of defects energy and collision energy. With increasing the milling time, substitution solid solution Ti(V) is formed in the process, without intermediate phase generated in the milling process. Milling for 40 h can produce nanocrystalline, while milling for 60 h can obtain nanocrystalline and polycrystalline mixtures with the grain sizes less than 60 nm. However, little change in grain size occurs with further milling after 60 h. After milling, the atomic ratio of Ti, Al, V approximates to 90:6:4, which is consistent with the elemental composition of Ti-6Al-4V.