Nonlinear Kinetics Theory For Interfacial Diffusion In Nanometer-scale Multilayers

The diffusion coefficients of atoms which strongly dependent on their local concentration are given in the nonlinear kinetic discrete model for diffusion in nonuniform system, and the diffusion asymmetry coefficient m' and the ordering energy V are introduced to describe the diffusion in nonuniform system. The diffusion of AB binary nanometer-scale multilayers with (V_BB-V_AA) =0, -0.03 eV and -0.08 eV, V =0. -0.025 eV and -0.05 eV in the diffusion direction [111] of fcc structure and [100] of bcc structure at the diffusion temperature of 800 K. 1000 K and 1250 K was calculated using the nonlinear kinetic discrete model, and the diffusion asymmetry coefficient m' and the ordering energy V were used to characterize the interfacial diffusion with variation of (V_BB-V_AA), the ordering energy V. diffusion temperature and diffusion direction in the AB binary nanometer-scale multilayers. With decreasing the diffusion asymmetry coefficient m'. the interfaces of nanometer-scale multilayers changed from broadening to sharpening during diffusion. When the ordering energy V decreased, the changes in concentration profile and interface structure were same for the multilayers with the same diffusion asymmetry coefficient m', but the diffusion time decreased correspondently. The difference of diffusion coefficient of A and B atoms resulted in by the diffusion asymmetry coefficient m' in the multilayers led to the difference of net fluxes of A and B atoms, which bing to the variation of interface structure in the multilayers during diffusion. The lower ordering energy V makes A and B atoms aggregating more easily during diffusion leading to the diffusion time decrease correspondently. The properties of nanometer-scale multilayers can be controlled by choosing appropriate AB binary system and treatment conditions according to the diffusion asymmetry coefficient m' and the ordering energy V of multilayers.Based on the relation between the nonlinear kinetic discrete model for diffusion in nonuniform system and classical diffusion law, the nonlinear kinetic discrete model can be transformed into the presences of Fick's First Law. Fick's Second Law and Cahn-Hilliard equation. The interfacial diffusion of Mo/V multilayers with modulation wavelength 4.8 ran...