Effects of Cr Content on Microstructure and Mechanical Properties of Ti5Mo5V3Al-xCr Alloys During Isothermal Aging

The microstructure and corresponding mechanical properties were studied of Ti5Mo5V3Al-xCr (x=1.0, 3.0, 5.0, 7.0 and 9.0) alloys quenched by solution treatment in β phase zone and isothermally aged at 550°C. The results show that the aging strengthening mechanism of Ti5Mo5V3Al-xCr alloys is mainly caused by the precipitation of as phase in the process of aging. The aging strengthening capacity of alloys is closely related to the number of as phase and the size of αs phase. As the Cr content increases, the ability to stabilize the β phase is higher, and the volume fraction of the unsteady β phase that can be decomposed is less, resulting in the less as phase that can be precipitated during the aging treatment and the larger the size of the corresponding αs phase. The strengthening effect becomes smaller.