Effect of Vanadium Concentration on the Structure and Properties of Ti–V Alloys Subjected to High-Pressure Torsion

The effect of preliminary annealing at 1000°C and subsequent high-pressure torsion (HPT) on the phase composition and mechanical properties of titanium alloys with 2, 4, 6, and 8 wt % V is studied. The increase in the V concentration in the initial alloy leads to an increase in the volume fraction of the β-Ti phase and a decrease in the volume fraction of the ω-Ti phase after HPT. The nanohardness Н and Young’s modulus Е were measured by nanoindentation. After HPT, the values of Н and Е are higher than those observed after preliminary annealing by 44 and 20%, respectively. The nanohardness and Young’s modulus of the studied alloy subjected to HPT are independent on the fraction of second constituent and are Н = 6.2 ± 0.2 GPa and Е = 138 ± 3 GPa, respectively. However, the hardness of the alloys subjected to HPT, which was measured by microindentation, also is independent of the fraction of the second constituent. At the same time, the ultimate strength and Young’s modulus measured by three-point bending technique have significant differences and, as the V concentration increases, decrease from 3.1 to 2.4 GPa and from 204 to 165 GPa, respectively. The decrease correlates with changing the volume fractions of the ω-Ti and β-Ti phases. The correlation between the vanadium content, phase composition, and ultimate strength of alloys subjected to HPT is found experimentally.