Electrical Resistivity Measured by Millisecond Pulse Heating in Comparison with Thermal Conductivity of the Superalloy Inconel 625 at Elevated Temperature

Abstract

Selected thermophysical properties of Inconel 625 were measured in continuation of our work on the comparison between thermal conductivity and electrical resistivity for different alloys. In contrast to pure metals, alloys usually show significant deviations from the Wiedemann–Franz law using the theoretical Sommerfeld value. Two experimentally determined constants can take into account mainly lattice and electron scattering contributions (Smith–Palmer plot), re-establishing a well-defined relation between thermal and electrical conductivity. Thermal diffusivity of Inconel 625 was measured by the laser flash method in the temperature range − 120 °C to 1250 °C; heat capacity was measured by differential scanning calorimetry in the temperature range − 170 °C to 1250 °C; thermal expansion was measured by dilatometry in the temperature range − 150 °C to 1295 °C (solidus temperature). Density at room temperature was measured by an Archimedean balance. From these experimentally obtained data, thermal conductivity was calculated in a wide temperature range. Electrical resistivity of Inconel 625 was measured by millisecond pulse heating in the temperature range from room temperature to the solidus temperature. The measurement results of electrical resistivity as a function of specific enthalpy were combined with results of specific heat capacity measurements to obtain the relation between resistivity and temperature.