Abstract
Single strain rate cycling tests were performed for commercial Ti-4Al, Ti-5Al-2.5Sn, Ti-6Al-4V and Ti-5Al-2Cr-1Fe alloys over the temperature range of 77 to 700°K. The effects of grain size and strain on the parameter m which was obtained directly from the tests were eliminated by employing the double extrapolation technique to yield ma*. ma* thus obtained for substitutional alloys still includes the effect of substitutional solute atoms on the athermal component as given by (ma*⁄β=σ*+σμ(Cs), so that the thermal component in substitutional alloys cannot be obtained simply by double extrapolations of m as in alpha titanium which contains only interstitial solute atoms. However, a comparison of the data for alpha titanium which contains no substitituional solute atom but the same interstitial solute content as the present Ti-4Al with those for Ti-4Al led to the conclusion that substitutional solute atoms do not influence the temperature dependence of the athermal component in the temperature range studied. σμ(Cs) was then determined at the temperature T0 where the (ma*⁄β)−T curve exhibited the inflection point. The thermal component in substitutional alloy σ*(ma*) which was estimated by subtracting [σμ(Cs)]T0 from (ma*⁄β) was in good accord with that estimated by using the conventional back extrapolation technique, and it is concluded that the double extrapolation technique can be applicable even to substitutional alloys whose temperature dependence of Young’s moduli is not known.
