Abstract
This chapter discusses two different approaches to estimating diffusion parameters from the bulk properties. First, empirical and semi-empirical correlations between diffusion and the bulk properties are discussed. These include the correlation of activation energy for self-diffusion with the cohesive energy, melting point, latent heat of fusion, bulk modulus, and the Debye temperature. The Zener's hypothesis, which paved the way for development of relationships between the diffusion parameters and the elastic modulus, is also discussed. Finally, a correlation between the activation energy for self-diffusion in metals with the valence bond parameter and that for solvent diffusion in dilute alloys with electron-to-atom ratio is presented. The empirical treatment of diffusion data is followed by the derivation of a thermodynamic relationship between the activation volume and activation entropy for self-diffusion. These two diffusion parameters are presented to be related to each other through the compressibility and the volume expansion coefficient. Since this equation does not contain any arbitrary constant, it is used to obtain the values of other diffusion parameters. Satisfactory agreement is obtained between the calculated and experimental values for all the parameters. The correlations between the bulk properties and the diffusion parameters discussed in the chapter can be used to rationalize new data and estimate the diffusion rates in the absence of experimental values.
Published Version
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