Mixing enthalpy measurements of liquid Ti-Zr, Fe-Ti-Zr and Fe-Ni-Zr alloys

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.