COHESIVE, ELECTRONIC AND MAGNETIC-PROPERTIES OF THE TRANSITION-METAL ALUMINIDES FEAL, COAL AND NIAL

Electronic structure calculations using the tight-binding linear muffi n tin orbital (TB-LMTO) method have been performed for three transitio n 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 expe rimental results as well as with existing theoretical calculations. Th e lattice constants, cohesive energies and heats of formation at equil ibrium lattice constants and bulk moduli agree with the experimental v alues. The calculations show varying degrees of charge transfer from A l site to the transition metal (TM) sites as one goes from FeAl to CoA l to NiAl. The magnetism of pure elements Fe, Co, Ni is mostly quenche d in the stoichiometric phases, with only FeAl retaining a magnetic mo ment of about 0.7 mu(B)/atom within the framework of the LMTO.