Intrinsic Diffusion Coefficient The Kirkendall Effect

The intrinsic diffusion coefficients, Dk and DB, of a binary alloy A-B express the diffusion of the components A and B relative to the lattice planes [7], Therefore, during interdiffusion, a net flux of atoms across any lattice plane is present, where, normally, the diffusion rates of the diffusing particles A and B are different. Subsequently, this interdiffusion process provokes the shift of lattice planes with respect to a fixed axis of the sample, result which is named the Kirkendall effect [9], 

The diffusion flux is proportional to the gradient of chemical potential [6], where the chemical potential of species i in a binary alloy is given by [7] 

For a nonideal solution, the gradient of the chemical potential is given by [9] 

The Physical Chemistry of Materials Energy and Environmental Applications 

neglecting correlation effects, since (see Equations 5.11 through 5.13) 

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