The Studies Of The Thermodynamic Properties Of The Rare Earth Binary Alloys

The atomistic simulations are becoming an increasingly powerful tool for studying the structure and properties of materials, with the development of the computer technologys and the rapid progress of the computational technique. The embedded atom method (EAM) is a very effectively simulation method of the typical atomic scale theories. And the EAM has been extensively applied in materials science.Based on Johnson's analytic EAM method frame, and balanced the advantages and disadvantages of available EAM models, the authors have proposed the general analytic embedded atom method (GAEAM). In the GAEAM, the crystal lattice constant, cohesion energy, mono-vacancy formation energy , bulk modulus and Rose equation are fitted. So we can describe the elements of without experimental elastic constants, and then extend the research fields. The GAEAM can describe the elements of BCC, FCC, HCP and Diamond structures.In the present work, the elastic constants, di-vacancy binding energy, the stability of structure, the surface energy, the dilute-solution energy of the binary alloys and the enthalpies of formation of disorder binary alloys in all components of rare earth, iron, aluminum and yttrium have been calculated. The phonon spectra of iron, aluminum, cerium and ytterbium are also given. The results are reasonable.Firstly, for the elastic constants, the calculated values are smaller than the experimental values, but the trend of the calculated values of the elastic constants is right. For the surface energy, the calculated values arc the 70% of the experimental polycrystalline average values. Thecalculated structured energy difference indicate that the present model can give correct structure, the calculated values of divacancy binding energy are reasonable.Secondly, for the dilute-solution energy of the binary alloys, the calculated values are agreement to the phases of the binary alloys. And for the enthalpy of formation of disorder binary alloys in all components, the calculated values are very good except the Al-Ce and Al-Yb.Thirdly, for the phonon spectra of iron, aluminum, cerium and ytterbium, there are discrepance the calculations and the experiments , the reasons are probably that the GAEAM has not fit the elastic constants.