Diffusional behavior of nanoscale lead inclusions in crystalline aluminum

Abstract

Abstract In-situ transmission electron microscopy (TEM) observations reveal a permanent chaotic motion of nanosized liquid Pb inclusions embedded in thin aluminum foils. Individual trajectories of the inclusions were analysed to determine the character of their motion. The inclusions moving freely inside a crystal display motion with three-dimensional random walk characteristics while inclusions attached to dislocations display spatially confined random motion localized to the close vicinity of the dislocation lines. The diffusion coefficients of inclusions moving freely in the matrix were determined using Einstein’s classical equation for diffusion of Brownian particles. The diffusion coefficients of inclusions trapped on dislocations were found using an equation based on Smoluchowski’s analysis of Brownian motion of a particle under the action of a linear elastic restoring force. The dependence of the diffusivity on the size of the inclusions suggests that their mobility is controlled by kinetic processes on the inclusion/matrix interfaces. The Arrhenius analysis exhibits two regions with different temperature dependencies. We suppose that this is related to the existence of {111} facets on the inclusion/matrix interfaces.