THERMALLY ACTIVATED DEFORMATION OF α TITANIUM BELOW 0.4 TM

Abstract

The effects of temperature, strain rate, and purity on the yield and flow stresses of α titanium at low temperatures (T < 0.4 T_M) are examined to ascertain the rate controlling dislocation mechanism. The effect of impurity content on the thermal component of the yield and flow stresses increases with the decrease in temperature to 0 °K. The activation volume for the plastic flow of titanium of commercial purity ranges from 80b³ at τ* = 1 kg/mm² to 8b³ at τ* = 45 kg/mm². The activation energy ranges from about 1.3 eV to 0.18 eV over the same stress range. The experimental data are in good accord with the thermally activated overcoming of interstitial atoms as the rate controlling mechanism and a linear force-distance curve with F_M = 43.2 × 10⁻⁶ dynes (0.9 × 10⁻¹ μb²), d₀ = 3.25b, and H₀ = 1.25 eV (0.21 μb³).