536.653:546.56′82We have used solution calorimetry at temperatures of 1573 K and 1873 K over broad concentration ranges to study the mixing enthalpy of Cu − Ti liquid alloys. The molar mixing enthalpies of the system are significant negative values. We have established the temperature dependence of the molar mixing enthalpies of the system: there is an increase in their exothermicity as the temperature is lowered. The significant negative mixing enthalpies of the system allow us to conclude that the chemical bonds are localized in the studied melts and consequently associates form. We tested this conclusion within ideal associated solution theory, which describes well the results obtained with a set of CuTi and CuTi 2 associates. Using the model obtained, we have calculated the excess thermodynamic functions of mixing (enthalpy, Gibbs free energy, heat capacity) for the liquid alloys. We estimated the Gibbs energies of fcc, bcc, and hcp solutions in the system by the CALPHAD method, using data from the initial sections of the phase diagrams and from the corresponding thermodynamic data. We have calculated the metastable phase equilibria between the limiting solid solutions and the liquid or supercooled liquid phase. It was shown that for the supercooled liquid and the amorphous phase, a broad concentration range of relative thermodynamic stability can be obtained. The concentration range of amorphization of Cu − Ti melts corresponds to the position of the metastable liquidus line and the T 0 line at temperatures close to the temperature range of amorphous solidification.The thermodynamic properties of liquid copper − titanium alloys are interesting especially in connection with the possibility of obtaining two-component metallic glasses in this system by quenching from the liquid [1-4] and the prospects for using this system as the basis for development of multicomponent compositions with low critical glassforming rates [5,6]. The possibility of melts passage in the system to the amorphous state can not be explained without analyzing the nature of the temperature-composition dependence of thermodynamic properties of competing phases. Furthermore, data on the thermodynamics of the process of copper and titanium alloy formation is limited and ambiguous.The formation enthalpies of liquid alloys of copper and titanium have been studied by calorimetric methods [7][8][9]. In [7,8], the integral mixing enthalpies of solid titanium with liquid copper were studied at 1373 K in the composition range 0.01 < x Ti < 0.70. Using these data, in [8] the integral mixing enthalpies were calculated for supercooled liquid titanium (Fig. 1a). The values of the first mixing enthalpy of titanium were found: −7.65 kJ/mole [7] and −9.0 kJ/mole [8], and also the minimum of integral mixing enthalpy: -3.8 kJ/mole [8].In [9], the partial mixing enthalpy of titanium with copper was studied in the composition range x Ti = 0-0.55 at a temperature of 1873 K. These data were obtained by recalculating the experimentally determined partial enthalpi...
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