High-Temperature Deformation Behavior of Alpha Ti-5.6 mol%Al Alloy

Abstract

Tensile tests were carried out on fine- and coarse-grained hcp Ti-5.6 mol%Al alloy in the temperature range from 1000 K to 1150 K under the strain-rate range from 1.1×10⁻⁶ s⁻¹ to 1.7×10⁻² s⁻¹ and the steady-state deformation characteristics were analyzed using the Dorn-type equation. Two stress ranges, other than the power-law breakdown, were recognized; the stress exponents were about 3.5 and 4.8 in the low and high stress ranges, respectively. The activation energy for creep was about 290 kJ/mol in both stress ranges, which is significantly larger than that for diffusion. The transition condition between two stress ranges depends little on the deformation conditions. The grain size affected mainly on the numerical factor of the Dorn-type equation.