Cohesive, electronic and magnetic properties of the transition metal aluminides FeAl CoAl and NiAl

Abstract

Electronic structure calculations using the tight-binding linear muffin tin orbital (TB-LMTO) method have been performed for three transition metal aluminides, viz. FeAl, CoAl and NiAl. The band structures and density of states (DOS), valence electron charge density contours and Fermi surfaces have been obtained and compared with the available experimental results as well as with existing theoretical calculations. The lattice constants, cohesive energies and heat of formation at equilibrium lattice constants and bulk moduli agree with the experimental values. The calculations show varying degrees of charge transfer from Al site to the transition metal (TM) sites as one goes from FeAl to CoAl to NiAl. The magnetism of pure elements Fe, Co, Ni is mostly quenched in the stoichiometric phases, with only FeAl retaining a magnetic moment of about 0.7 mu _B/atom within the framework of the LMTO.