STRUCTURAL, ELECTRONIC, AND MAGNETIC-PROPERTIES OF 3D TRANSITION-METAL ALUMINIDES WITH EQUIATOMIC COMPOSITION

First-principles calculations have been performed to study the chemical bonding trends and the phase stability of 3d transition-metal (TM) aluminides with equiatomic composition. The physical mechanisms for ordering in both the L10 and B2-type aluminides are presented. It is shown that the dominant factor for early TM aluminides is the directional bonding between the d orbitals of TM atoms, whereas for late TM aluminides, charge transfer and hybridization between Al s and p states, and TM d states play more important roles in the bonding mechanism and the properties of lattice defects. Our calculations also show the existence of a ferromagnetic phase for MnAl in the L10 structure, which is stabilized by the formation of a magnetic moment on the Mn sites (with a value of 2.0 B). The chemical trends in the structural stability and heats of formation of 3d TM aluminides are found to correlate well with the densities of states at the Fermi level. © 1995 The American Physical Society.