Potential energies of characteristic atoms on basis of experimental heats of formation of AuCu and AuCu3 compounds (Ⅰ)
(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China;
3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
4. College of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China)
2. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China;
3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
4. College of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China)
Abstract: 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.
Key words: systematic science of alloys; Au-Cu system; potential energy; heat of formation; order-disorder transition temperature