Melting Enthalpy and Entropy of Binary Systems of Alloys of 3d Transition VII and VIII Metals and Carbon: Thermodynamic Calculation and Experimental Study

Abstract

Thermodynamic calculations have been performed of the melting enthalpy and entropy of the Co–C, Ni–C, and Fe–C binary system alloys having eutectic compositions and of alloys whose compositions correspond to the minimum temperatures of the Mn–C, Fe–Co, Fe–Ni, and Mn–Ni melting diagrams. Heat capacities of one- and two-phase alloys of investigated systems have also been calculated as a function of temperature. In order to express a dependence of the Gibbs energy (G) of the liquid phase on the composition, the model of regular solutions has been used. The relation between the G of interstitial solid solutions and concentration was described by the two-sublattice model. The values have been experimentally verified using a high temperature calorimeter. These results have shown that the discrepancy between experimental and calculated results is within the calorimetric measurement uncertainty and does not exceed 10%.