Thermoelectric Properties of Titanium with Special Reference to the Allotropic Transformation

Abstract

A differential method for determining the thermoelectric power of titanium/platinum thermocouples is described. The results of the differential measurements are compared with data obtained in direct e.m.f. versus temperature determinations. From the thermoelectric power results, the temperature dependency of the following properties has been deduced : (a) the Peltier coefficient of the titanium/platinum couple ; (b) the difference between the Thomson coefficients of titanium and platinum ; (c) the absolute thermoelectric power of titanium. It is shown that abrupt changes in thermoelectric properties accompany the α-β transformation in refined titanium, the transition temperature range being 883 ± 1 to 887 ± 2 °C. In a commercial grade of titanium, the transformation occurs over the range 868 to 970 °C. Some effects due to preferred orientation and the elimination thereof are also reported.