Diffusion in the Presence of Grain Boundaries: a Variable Length Scale Simulation Method

Abstract

ABSTRACTIn this paper we introduce a Monte Carlo method for numerical analysis of the problem of tracer diffusion in the presence of isolated grain boundaries with a variable mesh in the direction perpendicular to the grain boundary plane. A number of isoconcentration contour profiles were studied. Two different expressions for the angle between the isoconcentration contours and the grain boundary were derived for the instantaneous tracer source following procedures analogous to Fisher's and Whipple's approximations for the constant tracer source. Comparison with the numerical data was made. Both these approximations overestimate the grain boundary diffusivity.