Solid-Solution Strengthening and Weakening of Vanadium–Titanium Alloys

AbstractThe thermal component, τ*, of the macroyield stress has been investigated for vanadium with 0.75, 1.6, 4, and 20 wt.-% titanium. The 4 wt.-% alloy showed a significant weakening effect below 100K. The temperature-dependence of the strain-rate-sensitivity for the alloys is discontinuous and indicates two different deformation mechanisms. At high temperatures a mechanism is operative that has a high H 0 value, i.e. 1.5eV. It is probably a distortion mechanism controlled by titanium atoms in clumps. At low temperatures the double-kink mechanism is rate-controlling. The titanium clumps can aid in the formation of double kinks by producing a torque on the screw dislocation. This torque reduces the τ* necessary for the formation of a double link, and therefore, “alloy weakening” is observed. The results strongly indicate that in relatively pure vanadium (< 50 at.-ppm) the impurity interstitials are not affecting τ*.