Density functional theory calculations on κ-carbides, (Fe,Mn)3AlC

We present density functional theory calculations on the structural, energetic, electronic, magnetic, and elastic properties of κ-carbides, (Fe,Mn)3AlC and their parent structure Fe3Al-L12. All the crystals have ferromagnetic ground state, and Fe3AlC is energetically most favored. The inclusion of C enhances the energetic stability, reduces the magnetization, and makes the crystal rigid. The Mn substitution has opposite effects for the energetics and magnetism, but corroborates that C addition hardens the crystals. The κ-carbides show an almost rigid band shift, and the electronic structure around the Fermi level is necessary to understand the property changes upon Mn substitution. We speculate that the configurational entropy may play an important role in stabilizing κ-carbides with finite Mn content.