SPECIFIC-HEAT AND RELATED THERMODYNAMIC FUNCTIONS OF UNDERCOOLED CU-NI AND AU MELTS

Heat capacity measurements on liquid stable and undercooled pure Au sa mples and Cu-Ni alloys were performed. Applying the melt fluxing techn ique, undercooling levels of 202 K and 272 K, respectively, could be r eached. The specific heat of the liquid, C-p(1) could be measured dire ctly by calorimetric diagnostics while undercooling the melt with a co oling rate of 10 K/min. Both metals show a rather weak dependence of C -p(1) on temperature. The differences of the thermodynamic functions b etween undercooled liquid and solid state were derived from the measur ed data of C-p and Delta H-f- the enthalpy of fusion, In particular th e difference in the Gibbs free energy Delta G is compared to well know n semiquantitative approximations. It is found that even the simple li near approximation can fit adequately the Delta G-data of the systems under study.