Thirty years of levitation melting calorimetry – a balance

Abstract

Investigations on liquid high melting metals are frequently tainted with side reactions with the crucible material. Levitation techniques enable the containerless investigation of thermophysical properties over a wide temperature range. An overview is given on enthalpy measurements by levitation drop calorimetry on solid and liquid metals using the electromagnetic levitation technique. The resulting melting enthalpies and melting entropies of the IVb-metals (Ti, Zr, Hf), the Vb-metals (V, Nb, Ta), and the VIb-metals (Cr, Mo, W) show a group dependence where the IVb-metals are characterized by melting entropies in the range 6.8–8 J mol −1 K −1, the Vb-metals have a value between 10 and 11 J mol −1 K −1, and the VIb-metals show melting entropies in the range 13–14 J mol −1 K −1. Another overview is given on mixing enthalpy measurements by levitation alloying calorimetry. The liquid Fe–Ti system is presented as an example for a temperature dependent mixing enthaply where modelling according to the regular associate model enables the calculation of the thermodynamic properties of mixing.