Mechanisms of primary creep in α/β titanium alloys at lower temperatures

Creep occurs in two phase α/β Ti alloys at room temperature and at stresses below the yield strength. In polycrystalline Ti alloys, creep strain exhibits two distinct power-law regimes, an initial higher exponent which exhausts to a constant value at longer times. However, the exhaustion is much more gradual than that for other metals at lower homologous temperatures. The deformation mode in creep involves heterogeneous planar dislocation arrays. This paper describes the details of the dislocation processes and the observations of dislocation interaction with α/β interface boundaries in lamellar colony structures.