The mixing enthalpy AH m of the liquid system Ni-Zr was measured in the Nirich range at 1916 K up to .Xzr = 0.34 at % and for the first time in the Zr-rich range at 2270 K up to -X' Ni = 0.54 at %. Using the thermodynamic-dapted power series, a composition-and temperature-dependent description of AH m was given. Furthermore, the partial differentiation of AHm(x, T) by T yielded the excess heat capacity CpX~(x, T). The existence of chemical short-range order (associate) in the vicinity of Ni7Zr2 and NiZr was shown and was discussed with reference to AHm(x, T) and CpX~(x, T) ( 1748 to 2270 K). With decreasing temperature, the influence of chemical short-range order tended toward the composition NiZr.

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The mixing enthalpies of liquid binary iron‐nickel, nickel‐chromium and iron‐chromium alloys were measured by levitation alloying calorimetry. The mixing enthalpy of iron‐nickel alloys is asymmetric and was described by an equation according to the modified quasichemical solution model. Liquid nickel‐chromium alloys were determined to conform to a regular solution model whereas the system iron‐chromium behaves ideally. Based upon the analytical descriptions obtained for the binary systems an isoenthalpy diagram for liquid ternary iron‐nickel‐chromium alloys was calculated. Mixing enthalpy measurements of the concentration section Fe35Ni65 ‐ Cr are in agreement with the model calculation. Iron rich alloys of the system tend to almost ideal behaviour whereas nickel rich alloys are characterized by negative mixing enthalpies up to ‐5 kJ/mol.

The mixing enthalpies of liquid Ti‐Zr, Fe‐Ti‐Zr and Fe‐Ni‐Zr alloys were measured by levitation alloying calorimetry. The mixing enthalpy of Ti‐Zr alloys is slightly exothermic and symmetric with an extreme value of −5.2 kj mol−1. It can be described according to the regular solution model. Experimental investigations of the mixing enthalpies of the strongly non‐ideal binary systems Fe‐Ti, Fe‐Zr and Ni‐Zr had already been subject of earlier works. Based on experimental data temperature dependent descriptions of the mixing enthalpies were calculated with a regular associate model. From the model parameters of the binary subsystems the mixing enthalpy of the respective ternary system can be predicted. Model calculations of the mixing enthalpies of liquid Fe‐Ti‐Zr and Fe‐Ni‐Zr alloys were performed along different concentration sections and compared with experimental data, respectively. A good accordance was observed. The mixing enthalpies of liquid Fe‐Ti‐Zr and Fe‐Ni‐Zr alloys are given at T = 2152 K and T = 1892 K in form of isoenthalpy diagrams, respectively. Moreover, with help of the temperature dependence of the mixing enthalpy the excess heat capacities of the alloys were calculated.