Measurement of Specific Heat Capacity and Electrical Resistivity of Industrial Alloys Using Pulse Heating Techniques

The determination of the specific heat capacity and electrical resistivity of Inconel 718, Ti-6Al-4V, and CF8M stainless steel, from room temperature to near the melting temperatures of the alloys, is described. The method is based on rapid resistive self-heating of a solid cylindrical specimen by the passage of a short-duration electric current pulse through it while simultaneously measuring the pertinent experimental quantities (i.e., voltage drop, current, and specimen temperature). From room temperature to about 1300 K, the properties are measured using an iIntermediate-temperature pulse-heating system by supplying a constant current from a programmable power supply and measuring the temperature using a Pt-Pt:13% Rh thermocouple welded to the surface of the specimen. From 1350 K to near the melting temperatures of the alloys, the properties are measured using a millisecond-resolution high-temperature pulseheating system by supplying the current from a set of batteries controlled by a fast-response switching system and measuring the temperature using a highspeed pyrometer in conjunction with an ellipsometer, which is used to measure the corresponding spectral emissivity. The present study extends the application of these techniques, previously applied only to pure metals, to industrial alloys.