Potential energies of characteristic atoms on basis of experimental heats of formation of AuCu and AuCu3 compounds (I)

The systematic science of alloys(SSA) is a framework of the total energy and total volume able to be separated. The potential energy sequences of characteristic atoms at the central sites of the basic clusters in the fcc-based lattice Au-Cu system are separated out from smaller experimental heats of formation of L10-AuCu and L12-AuCu3 compounds only, by nine potential energy E-functions and through the use of structural unit inversion method. From these potential energy sequences, the potential energies and heats of formation of the disordered Au1−xCux alloys at 0 K are calculated. The potential energies, heats of formation and Tc-temperatures of order-disorder transitions of the L10-AuCu, L12-Au3Cu and L12-AuCu3 compounds, as well as the Au3Cu-, AuCu-and AuCu3- type ordered alloys with maximal ordering degrees are calculated too. The results show that the 5th E-function may be chosen for developing it into the free energy-, enthalpy-, vibrational energy- and vibrational entropy-functions for describing thermodynamic properties of the compounds, ordered and disordered phases and for establishing the phase diagram of the Au-Cu system in the future.