Enthalpy of formation of intermetallic phases from the Au-Sn system

Solution calorimetry with liquid Sn has been used for the determination of enthalpy of solution of Au and enthalpy of formation of intermetallic compounds from the Au-Sn system. Enthalpy of solution of liquid Au in liquid Sn was measured at 667 K to be −34.3 ± 0.5 kJ/g-atom and it was almost the same as cited in many earlier references. Based on the literature and this study data parabolic equations of temperature dependence of enthalpy of gold solution in liquid tin were worked out for three groups of data. Intermetallic phases were prepared and homogenized in the glow-box operated in high purity argon. They were analyzed by X-ray diffraction method before the calorimetric investigations to confirm their crystallographic structure. The obtained experimental values of enthalpy of formation were −15.3 ± 0.3, −14.2 ± 0.3 and −7.9 ± 0.6 kJ/mol of atoms for AuSn, AuSn2 and AuSn4, respectively. It was found that the obtained data in the study agreed very well with the results previously presented in literature. The observed differences were not higher than 0.5 kJ/mol of atoms.