Abstract:The new muti-compositional Ti2AlNb alloy Ti-22Al-25Nb-1Mo-1V-1Zr-0.2Si was treated by the process of near beta forging and heat treatment. The effect of heat treatment on the microstructure and mechanical properties were analyzed by means of the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile test machine. The results show that the initial microstructure contains the primary α2 phase, the needle like O phase and the matrix B2 phase. On the one hand, with the increasing of solid solution temperature, the alloy strength is enhanced at room and high temperature, but the alloy ductility is reduced. On the other hand, with the increasing of aging temperature, the variation of strength and ductility is completely opposite, compared to the increasing of solid solution temperature. It is analyzed that the primary alpha phase volume fraction α2/O was mainly influenced by the solid solution treatment for the alloy. With the increasing of the solution temperature, the α2 /O primary alpha phase volume fraction is reduced, leading to the strengthening effect of needle like O phases enhanced. At the same time, the grain boundary pinning effect of the α2 phase to B2 is weaken, then the B2 grain growth cause the plasticity decrease. The morphology of precipitated phase is mainly affected by aging treatment. With the decreasing of aging temperature, the thickness of precipitated fine strip phase decrease, which makes the strengthening effect of fine strip increase, the volume fraction of B2 phase decrease, and the ductility of the alloy reduce.