Effect of heat treatment on microstructure and mechanical properties of cast Ti15 - 3 alloy

The effect of heat treatment on the microstructure and mechanical properties of cast Ti15 - 3 alloy have been studied by means of TEM, SEM and optical microscope, and results show microstructure of as cast alloy is characterized as large beta grains. For lack of strengthening action of precipitation, the tensile strength of the alloy is low but its elongation is high. After solution treatment Hollowed by different aging treatments, it was observed that alpha phases precipitated in the grains or at the grain boundaries. With the aging temperature rising or holding time prolonged, the precipitation phases become coarser continuously. Compared with the as cast condition, the tensile strength of as heat treated alloy was considerably increased, but the elongation was dramatically decreased. Meanwhile, the dislocation tangled around the precipitation phases during the deformation process. The reasons for lower plasticity of alloy can be interpreted as the original large beta grains and the precipitation of alpha hases at the grain boundaries.