Thermal-cycling creep of γ-TiAl-based alloys

In two-phase TiAl-based alloys, the coexisting α2 and γ phases exhibit a thermal expansion mismatch, so that increased creep rates during thermal cycling may be expected. Creep deformation of two γ-TiAl-based alloys was investigated during thermal cycles between 900 and 300 or 350°C with applied tensile stresses of 32.5 or 37.0 MPa. Measured thermal cycling creep rates were compared with isothermal creep rates calculated at the effective average temperature. No creep enhancement was measured upon thermal cycling within uncertainties of 1.6×10−3% strain per cycle.