Effect of thermal exposure on microstructure and mechanical properties of laser deposited Ti60A high temperature titanium alloy

Microstructure and tensile properties of laser deposited Ti60A high temperature titanium alloy was investigated after 600℃, 100 h isothermal exposure and cyclic thermal exposure. Results indicate that the volume fraction of α phase increases slightly after isothermal exposure. While the broken β and coarsened α platelets occur in the alloy after cyclic thermal exposure and the volume fraction of α phase even increases about 12%. The precipitation of fine ordered coherent Ti₃Al and 100~150 nm hexagonal quaxi-S₂ type ellipsoidal silicide (TiZr_0.3)₆Si₃ is nearly the same in the alloy after isothermal or cyclic thermal exposure. The tensile properties of the alloy are significantly decreased after thermal exposure. In particular, the ductility of the alloy after cyclic thermal exposure is almost lost, which is closely related to the obvious microstructural changes produced by cyclic thermal stress.