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

Creep behavior of the conventional Ti-6Al-4V alloy with a Widmanstatten 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 degrees C, respectively. By incorporating the threshold stress into analysis, the creep data can be rationalized to stress exponents of 4.4 at 500 degrees C and 4.1 at 600 degrees C, which are consistent with the lattice diffusion controlled dislocation climb process in alpha-Ti. In the preliminary study, creep properties of alpha-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 a-Ti and composites. Apparently, the higher creep resistance of Ti-6Al-4V can be attributed to alpha/beta interfaces acting as obstacles to dislocation motion and to the average grain size of 395 mu m, which reduces the grain boundary sliding, dislocations sources and the rate of oxygen diffusion along grain boundaries. (c) 2006 Elsevier B.V. All rights reserved.