Stability of the microstructure and properties of Ti2AlNb alloys under thermal exposure conditions

In this paper, the microstructure and property stability of Ti2AlNb alloy specimens treated by thermal exposure at 800°C for 0~12h were investigated using universal tensile tester, X-ray diffractometer, scanning electron microscope, electron backscattering diffraction, and in-situ tensile scanning electron microscope. The results show that with the extension of thermal exposure time, the tensile strength and yield strength of the alloy slightly increased, the B2-phase of the alloy decreased while the O-phase increased, and the content of the α2-phase also slightly decreased. It has been found that the properties changes are related to the changes of microstructure. The tensile cracks expanded along the grain boundaries between the O-phase and B2-phase as well as along the O-phase grain boundaries. The slight changes in microstructure and properties indicate that the Ti2AlNb alloy is stable and reliable for short-term service at 800 °C.