Hot deformation behavior and microstructure evolution of TC11（Ti-6.5Al-3.5Mo-1.5Zr-0.3Si） alloy with equiaxed structure were investigated in the two-phase field at temperatures in the range of 980-800 ℃ and at strain rates of 0.001 s-1,0.01 s-1,0.1 s-1.Effects of thermo-mechanical parameters on both of the stress—strain curves and microstructure evolution were analyzed.Grain boundary characteristics of deformation microstructures were tested by electron backscattered diffraction（EBSD）.The results reveal that β-phase dominates the deformation and presents discontinuous dynamic recrystallization at 980 ℃;meanwhile,α-phase coarsens at lower strain rates and dissolves at higher strain rates,and α-phase volume fraction and grain size decrease with increasing strain rate.Super-plastic deformation occurs at 950-900 ℃ and strain rate of 0.001 s-1.And the deformation is dominated by soft β-phase,phase interfaces and grain boundaries.Microstructural mechanism operated at 850 ℃ is continuous dynamic recrystallization of α-phase that dominates the deformation,and β-phase deforms to match the deformation of α-phase.
