Abstract
The effect of grain size (1 to 12 μm) on the deformation kinetics in a Ti-7.4 at%Al alloy was investigated over the temperature range of 77 to 700°K. It was found that grain size primarily influences the athermal component of the flow stress, the thermal component being independent of grain size and the same as that of unalloyed titanium of the same interstitial solute content. The deformation kinetics obey an Arrhenius-type rate equation with a Gibbs free energy of activation at σ*=0 and 0°K equal to ∼1.4eV(∼0.2 μ0b3). It was concluded the thermal activation parameters for the plastic deformation of the alloy are the same as those of unalloyed titanium and the rate controlling mechanism is the thermally activated overcoming of interstitial solute atoms by moving dislocations.
