Two CuMnNi alloys, both similar to Manganin (R) in chemical composition, were studied in this work. By means of DTA measurements, the solidus and liquidus temperatures were measured for both alloys. To determine thermal volumetric expansion, specific electrical resistivity and specific enthalpy in the temperature range from 1000 K to 1900 K, the fast ohmic pulse-heating technique was used, where a wire shaped specimen is heated up into the liquid phase by passing a large current pulse through the sample. Additionally, chemical analyses of both investigated alloys were made to identify the difference in their chemical compositions. A comparison of the measured data sets, showing that thermophysical properties for the investigated alloys differ, will be presented within this work.

The two closely related properties, the thermal diffusivity and conductivity, are of great interest for all questions concerning heat transfer and thermal effects (e.g. heat transport, conduction, dissipation, etc.). However, measurements of these properties still lead to widespread results depending on the respective measurement technique used. This experience was used as a starting point for a common research project with Böhler Edelstahl GmbH & Co KG supported by FFG, whose main target is to compare directly and indirectly obtained diffusivities of highly alloyed steels. For this purpose, thermal diffusivity is on the one hand directly measured by means of a quasistatic laser flash technique (LFA) and, on the other hand, indirectly calculated via the Wiedemann-Franz law (WFL) from electrical resistivities. The latter are measured by means of a fast dynamic ohmic pulse-heating system capable of measuring a wide range of thermophysical and optical properties of conducting materials up to temperatures beyond melting into the liquid state.