Microstructure and mechanical properties of a new Ti2AlNb-based alloy after aging treatment

Abstract

A new Ti2AlNb-based alloy with the composition of Ti–22Al–25Nb–1Mo–1V–1Zr–0.2Si (at%) was fabricated in the sequence of arc melting, forging, solid solution and aging. Present paper focuses on the effects of aging temperatures (700, 750, 800, 850 and 900 °C) on microstructure, room-temperature tensile properties as well as tensile properties at 650 °C and creep properties at 650 °C/150 MPa. It is obvious that the aging treatment promotes the precipitation of O lathes from B2 matrix. With aging temperature increasing, the content of O phase decreases and its size increases gradually, which leads to the decrease in tensile strengths both at room temperature and 650 °C and a little increase in ductility. For creep properties, the sample aged at 700 °C shows the best creep resistance due to its extremely high O phase content. Aging at 800 °C leads to the decrease in the content of O phase and softening of the alloy significantly. However, with aging temperature further increasing from 800 to 900 °C, the precipitated O phase will be coarsened gradually, which strengthens the alloy again.