Creep behavior in an extruded β solid solution Nb-Ti base alloy

This paper presents the results of a study of the creep behavior of a β solid solution 44Nb-35Ti-6Al-5Cr-8V-1W-0.5Mo-0.5Hf (at.%) alloy. Heat treatments on longitudinal and transversely oriented specimens obtained from the commercially produced 8-cm diameter extrusion revealed that thermal exposure at 1 h at 1200 °C produced a recrystallized β structure that was stable between 25 and 704 °C. The recrystallized structure had remarkable tensile strength and ductility within this range. Tension creep studies were carried out at 704 °C and 104 MPa in an effort to simulate potential service conditions. These revealed a short primary creep regime prior to a limited steady-state regime and an extended tertiary creep regime. Inverted creep behavior was also observed in the primary creep regime, which is indicative of Class I creep. After creep deformation, a range of dislocation configurations was observed. These include dislocations looping around TiC particles, dislocations grazing TiC particles, kinked dislocations, bowed dislocations, and dissociated dislocations.