Electronic structure of grain boundaries in the Fe86-Mn12.7-C1.3alloy

Abstract

The importance of studying Fe-Mn-C alloys is related to their wide use as constructional materials in mechanical engineering. In this work an effort has been made to elucidate the physical origin of the magnetization in austenitic steels by calculating the electronic structure of grain boundaries. To theoretically investigate the magnetic properties of a crystal of ferromagnetic bcc iron, the wave functions of the iron atom calculated in view of the spin polarization of a core by the Hartree-Fock method with local exchange-correlation potentials have been used as base functions. This has made it possible to optimize the choice of a zero approximation for the description of the electronic states of ferromagnetic iron and to attain good agreement with the experimental values of the magnetic moment (μ theor = 2.23μ B , μ exp = 2.218μ B ), of the exchange splitting of the crystal term P 4 (Δ theor = Δ exp = 0.112 Ry), and of the cross-sections of the Fermi surface. A similar approach has been used to investigate the magnetic states of clusters (nanoclusters) based on the method of scattered waves. The approach developed for clusters of the alloy under investigation makes it possible to calculate the alloy magnetic properties in relation to the cluster size for a varied lattice parameter.