Creep behavior of Ti–6Al–4V and a comparison with titanium matrix composites

Creep behavior of the conventional Ti–6Al–4V alloy with a Widmanstätten microstructure has been investigated in air under constant load tensile tests. The stress exponent values of 11.3 and 5.2 were obtained at 500 and 600 °C, respectively. By incorporating the threshold stress into analysis, the creep data can be rationalized to stress exponents of 4.4 at 500 °C and 4.1 at 600 °C, which are consistent with the lattice diffusion controlled dislocation climb process in α-Ti. In the preliminary study, creep properties of α-Ti, TiBw/Ti and TiCp/Ti–6Al–4V have been collected from literature and compared with those of Ti–6Al–4V obtained in this work in the applied stress range of 97–472 MPa. Creep strain rates of the conventional Ti–6Al–4V alloy are lower than those of the α-Ti and composites. Apparently, the higher creep resistance of Ti–6Al–4V can be attributed to α/β interfaces acting as obstacles to dislocation motion and to the average grain size of 395 μm, which reduces the grain boundary sliding, dislocations sources and the rate of oxygen diffusion along grain boundaries.