Free energy calculation of quasicrystal phase Al₆CuMg₄ under electric field

Based on Thomas-Fermi model, the change trend of free energy and Gibbs free energy of quasicrystal Al₆CuMg₄ against Al-Cu-Mg solid solution and compound Al₂CuMg were calculated systematically and quantitatively. The main conclusion was following: free energy and Gibbs free energy of quasicrystal phase Al₆CuMg₄, Al₂CuMg and Al-Cu-Mg solid solution increased with increasing of electric field. The effect of positive electric field was more intensive than the negative electric field, but their different was not big. The change trend of free energy and Gibbs free energy of quasicrystal Al₆CuMg₄ with the electric field was more sensitive than that of solid solution. With increasing of electric field, the differences of free energy and Gibbs free energy between Al₆CuMg₄ and solid solution increased quickly. The instability of quasicrystal increased under electric field. The stability of Al₂CuMg under electric field was obviously higher than that of Al₆CuMg₄. For Al-Cu-Mg solid solution, the sensitivity increased with increasing of the Mg content, but the amplitude was far lower than those of the compound and quasicrystal.