Quantitative high temperature calorimetry on precipitation in steel and nickel alloys

This work presents a method for the in-situ analysis of solid-solid-phase transformations in precipitation hardening alloys at high temperatures (typically 600-1100 degrees C). It shows that the Differential Scanning Calorimetry (DSC) methodology originally introduced for low temperatures (typically below 600 degrees C, e.g. Al-alloys) can be successfully adapted for continuous heating and even continuous cooling on high temperature alloys such as martensitic precipitation hardening steel X5CrNiCuNb16.4 (17.4 PH) as well as the Ni-based superalloys, Inconel 718 and Rene 65. The high temperature DSC Setaram Labsys EVO was used with both continuous heating, as well as continuous cooling, experiments being performed, using rates of 0.01 to 0.3 K/s. One challenge for high temperature DSC analysis is to find an appropriate reference material. Hence different strategies to obtain quantitative data are discussed.