Evolution of Dislocation Structure During Room Temperature Compressive Creep of a New α + β Titanium Alloy

A precise understanding of cold compressive creep behavior is essential for elucidating the failure mechanisms of titanium pressure hulls in deep-sea service and designing enhanced alloys with optimized performance. In this study, we systematically investigated room temperature compressive creep mechanisms in an α + β titanium alloy featuring a multi-level lamellar microstructure under varying applied stresses, using transmission electron microscopy (TEM) analysis. At an applied stress of 0.75σ_0.2, the alloy exhibits minimal plastic strain accumulation, with most dislocations remaining immobile. Once the stress threshold is exceeded, planar slip initiates along the prismatic plane, followed by the activation of basal and pyramidal slip at higher stress levels. Under high stress (0.95σ_0.2), creep deformation is primarily governed by prismatic and basal slip. Slip transfer between similar oriented grains within a microtextured region frequently occurs at stresses above 0.83σ_0.2. Additionally, we observed that higher applied stresses suppress the cross-slip of prismatic screw <a> dislocations within the α grains.