Room temperature deformation and mechanisms of slip transmission in oriented single-colony crystals of an α/ β titanium alloy

Primary creep at low homologous temperatures and low stresses has been widely reported in α/ β Ti alloys. Creep in these alloys is dependent on microstructure, with the colony microstructure showing the least creep resistance. There exists a Burgers orientation relationship between the α and the β phase, which has been assumed to allow for easy slip transmission across the α/ β interfaces. Constant strain rate and creep tests were performed on single-colony crystals of a near- α alloy oriented for slip along different prismatic slip systems in the α phase. A distinct anisotropy in the deformation behavior of different colony crystals is found. The origin of this anisotropy is due to the relative misalignment of the slip systems between the α and the β phases which results in the formation of residual dislocations during slip transmission. A simple model is presented based on the accumulation of residual dislocations at both the α/ β interface and the α matrix, which provides insight into the mechanism of slip transmission, strain hardening and primary creep of these colony structures.