Effect of vanadium on hot deformation and microstructural evolution of 7150 aluminum alloy

摘要

The hot deformation behavior of 7150 aluminum alloys containing different V contents (0.01-0.19 wt%) was studied using uniaxial compression tests conducted at various temperatures (300-450℃) and strain rates (0.001-10 s~(-1)). The results reveal the peak flow stresses of the 7150 alloy significantly increased when V was added. The alloys containing 0.03-0.05% V displayed higher values of peak flow stress than those with 0.11-0.19% V at low temperatures, whereas they displayed comparable values at higher temperatures. The materials constants and activation energies for hot deformation were determined from the experimental compression data for all the alloys studied. The activation energy for hot deformation increased from 229 kJ/mol for the base alloy to approximately 270 kJ/mol for the alloys containing 0.03-0.05% V. With further increases in V contents up to 0.19%, the activation energy returned to approximately 250 kJ/mol. The vanadium-solute diffusion acted as the deformation rate-controlling mechanism for the alloys containing up to 0.05% V, resulting in enhanced work hardening and improved subgrain strengthening effects. The precipitation of Al_(21)V_2 dispersoids in the alloys containing 0.11-0.19% V promoted the retardation of dynamic recovery and the inhibition of dynamic recrystallization due to their pinning effect on dislocation motion and subgrain rotation.