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

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 iInterstitial 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%.