Atomic and Electronic Structures of Tilt Grain Boundaries in BCC Transition Metals

Abstract

A tight-binding type electronic theory is used to calculate the configurational and electronic structures of coincidence-related tilt grain boundaries in bcc transition metals α-Fe, Mo and W. To obtain the atomic configurations near the grain boundaries, both electronic (d-band) and repulsive energies are calculated and minimized: The change in the d-band energy ΔE_d is obtained using the second moment Gaussian approximation for the d-density of states (DOS), while the Born-Mayer potential is used to estimate the change in the short-range repulsive energies. It is shown that the grain boundary structures depend sensitively on the species of transition metals, and the asymmetric grain boundaries can be stabilized for certain transition metals. We also present the local DOS of d-electrons, calculated using the recursion method, on the atomic sites near the tilt grain boundaries.