Enthalpy of formation of Au-Sn intermetallic phases. Part II

The technique of solution calorimetry with liquid Sn has been used for the determination of enthalpy of formation of intermetallic compounds from the Au-Sn system. The intermetallic phases were prepared and homogenized in a glow-box operated in high purity argon. They were analyzed by an X-ray diffraction method before the calorimetric investigations to confirm their crystallographic structure. The obtained experimental values of enthalpy of formation were -5.8 ± 0.3 and -1.3 ± 0.4 kJ/mole of atoms for ζ'-Au5Sn, and ζ-Au5Sn of the composition Au89Sn11, respectively. Using the DTA technique the transition temperatures were measured for the following phases: η-AuSn4, ε-AuSn2, δ-AuSn, ζ'-Au5Sn and ζ-Au5Sn (Au89Sn11). It was found that the obtained data in the study agreed very well with the results previously presented in literature, except for the ζ-Au5Sn (Au89Sn11) intermetallic phase, for which a difference of about 50o was observed for the liquidus temperature.