Effect of Molybdenum on the Electronic Structure of Iron Grain Boundaries with Phosphorus and Boron

Abstract

AbstractWe are reporting preliminary results on LMTO supercell calculations on a Σ3 (111) grain boundary (GB) in Fe with Mo atoms sitting at the GB plane. Calculations were performed both for the clean (CL) GB and GB with P/B atoms occupying centers of host (Fe and Mo) atom trigonal prisms (a coordination typical of the Fe GBs). The geometry of the GBs was not changed upon substituting Mo for Fe in the GB plane: all the interplanar distances and atomic radii were preserved (these were calculated earlier for the Fe GBs from GB3 relaxation modelling using the Embedded Atom Method). Comparison of the electron charge-density distributions within the atomic spheres for GBs with and without Mo, has shown that the presence of Mo at the GB plane increases both the number of d-electrons and the total charge density within atomic spheres of the atoms most important for intergranular cohesion. This should result in enhanced cohesion. The magnetic moments of the constituent atoms were also found to be strongly affected by the addition of Mo. The Mo atoms are anti-ferromagnetically coupled with the neighboring Fe atoms: mM0=-O.6OμB (CL GB), mMo=-O.14μB (GB with P), and mMo=-O.18μB (GB with B).