Mobility of U Solutes in fcc Al: A Theoretical Model

Abstract

We propose a theoretical model for characterizing the diffusion of solute atoms, driven by vacancy migration. Our model requires only a few static calculations, in the same line of ideas as the five-frequency model. We obtain microscopic parameters, namely: i) the free energy of vacancy formation and the vacancy-solute binding energy, ii) the tracer correlation factor, (ii) the solvent-enhancement factor, and iii) the involved jump frequency. In this paper, we specifically perform calculations in (Al,U) diluted fcc alloy. Our results show excellent agreement with available experimental data for pure Al solvent, and also with result from molecular dynamic calculations for the U mobility diluted in Al. Qualitatively, we conclude that the U solutes diffuse through a drag mechanism.