Effect of heat treatment on microstructure and mechanical property of Ti-6Al-2.5V-1.5Fe-0.15O alloy

The effect of solid solution temperature and aging temperature in different cooling rates on microstructure and mechanical properties of Ti-6Al-2.5V-1.5Fe-0.15O alloy prepared by vacuum non-consumable arc melting process was studied. It was found that solid solution temperature mainly affects the content of primary α, and the type of solid solution cooling method has important effect on the type of primary α. Aging temperature will change the morphology of aging α phase. When the single phase zone is in solid solution, primary α phase disappears. The structure of the alloy after solid solution quenching is mainly composed of the residual phase and the needle like α'. With the increase of solid solution temperature, the needle like α' increases. After solid solution in the two phase region, α phase, aging α phase and residual β phase all exist. At lower aging temperature, nuclear power and element diffusion α phase is lower. By means of saturated β phase precipitated nucleation, acicular α phase is fine and dispersive. With increase of aging temperature, nucleation energy of α phase is larger. Aging phase is easy to grow up. After solution-aging treatment, the strength of the alloy increases slightly firstly and then decreases with increase of temperature. Plasticity firstly increases and then decreases due to grain boundary coarsening and coarse lamellar α cluster.