First-principles calculations of stability and phase equilibria in the Fe–Ni system

摘要

Following the previous first-principles calculations on Fe–Pt system, we derive a L10-disorder phase diagram, spinodal ordering temperature, and short-range order diffuse intensity spectrum for Fe–Ni system. It is confirmed that L10-disorder transformation at 50 at.% is of the first order by the temperature dependence of the Long-Range Order parameter, however, at 60 % Ni, two-phase region starts disappear and the second-order feature appears. This is further confirmed by the merging of the locus of spinodal ordering temperature and order–disorder phase boundary. The intensity maximum of the short-range order diffuse intensity spectrum appears at (1, 0, 0) position in the k-space which is the characteristic concentration wave of the underlying L10 ordered phase.