The microstructure and creep behaviour of Ti-25Al-10Nb-3V-1Mo (super α2)

Low-oxygen plasma-melted Ti-25Al-10Nb-3V-1Mo (super α2) has been isothermally upset forged at 1050 °C (α2 + β phase field) and then heat-treated to produce different microstructures. The creep behaviour has been examined as a function of microstructure, stress and temperature. Test temperature ranged from 650 °C to 750 °C, test stress ranged from about 50 MPa to about 200 MPa and the tests were conducted in air. The microstructures of specimens were examined by optical and transmission electron microscopy. The steady state creep rate, apparent stress exponent and apparent creep activation energy of the various samples have been determined and compared with those in the literature. The results show, as expected, that the creep properties are strongly influenced by microstructure. The significance of these observations is discussed in terms of the parameters that control secondary creep in super α2.