On the electronic structure of ordered and substitutional disordered Fe-Al and Fe-Al-Ti alloys

We present first principle total energy KKR-CPA calculations (1)of $Fe_0_._5- Al_0_._5$ and $Fe_0_._4_7_5- Al_0_._4_7_5-Ti_0_.0_5$ alloys, both in the ordered and random crystal structure. We found that the ordered B2 crystal structure is always more stable with respect to the random alloys. This behaviour is discussed in terms of the electronic structure. The last is characterized by almost orizontal Fe d bands at the Fermi energy. The disorder induced broadening of these states does not allow the definition of a neat Fermi surface in the random phases(2). The addition of Ti does not change qualitatively the energetic behaviour of the systems. We found however a remarkable energy shift between Ti d states on different sublattices of the B2 structure.