Effects of strain rate and temperature on mechanical behaviour of Ti-15Mo-5Zr-3Al alloy

This study uses the compressive split-Hopkinson pressure bar to investigate the mechanical behaviour of Ti-15Mo-5Zr-3Al alloy deformed at strain rates ranging from 8×10² to 8×10³ s^-1 and temperatures between 298 and 1173 K. The results indicate that the mechanical behaviour of the alloy is highly sensitive to both the strain rate and the temperature. The flow stress curves are found to include a work hardening region and a work softening region. The strain rate sensitivity parameter, m, increases with increasing strain and strain rate, but decreases with increasing temperature. The activation energy varies inversely with the flow stress, and has a low value at high deformation strain rates or low temperatures. Correlating the mechanical properties of the Ti alloy with the transmission electron microscope (TEM) observations, it is concluded that the precipitation of α phase dominates the fracture strain. TEM observations reveal that the amount of α phase increases with increasing temperature below the β transus temperature. The maximum amount of α phase is formed at a temperature of 973 K and results in the minimum fracture strain observed under the current loading conditions.