Thermal activation parameters of V-5Cr-5Ti alloy under hot compression

In order to well understand the elementary mechanisms that govern the hot working process of a V-5Cr-5Ti alloy (mass fraction, %), thermal activation parameters under compression were measured in a temperature range of 1373-1673 K by a Gleeble-3800 system. The results show that the stress exponent n is 4.87 and the activation energy Q is 375.89 kJ/mol for the power law equation. The activation energy is determined as 288.34 kJ/mol, which is close to the self-diffusion energy of alloy (270-300 kJ/mol) by introducing a threshold stress(σ0) variable. The typical values of physical activation volume (Vp) and strain rate sensitivity (m) are measured as (120-700) b3 and 0.075-0.122, respectively, by the repeated stress relaxation tests. These activation parameters indicate that the rate controlling mechanism for V-5Cr-5Ti alloy compressed in ranges of 1373-1673 K and 0.001-1.0 s−1 is the dislocation climb by overcoming of forest dislocations.