A thermodynamic study of copper-iron and copper-cobalt liquid alloys by mass spectrometry

The thermodynamic activities in the liquid Cu-Fe and Cu-Co binary systems were measured by a high temperature mass spectrometric technique. From the obtained data, the heats of mixing in the Cu-Co liquid binary were calculated. Both the Cu-Fe and Cu-Co systems are thermodynamically similar, with large positive deviations from ideality in the activities. The activity coefficients in the liquid Cu-Co system at 1823 K were found to be symmetrical and can be expressed by lnγCu= 1.76X Co 2 The heat of mixing in the liquid Cu-Co system was found to be described by a cubic function δHm = −17.9 Co 3 − 7.6X Co 2 + 25.5Co (kJ/mol) The activity coefficients in the liquid Cu-Fe system at 1873 K were found to satisfy two quadratic formalisms in the binary In γCu = 2.10X Fe 2 − 0.13 0.65 ≤X Fe ≤ 1 In γFe = 1.79X Cu 2 + 0.04 0 ≤X Fe ≤ 0.65