Graphical-numerical determination of variable diffusion coefficient in solids



Considerable gain in information in characteristics of diffusion coefficient may be obtained if data are analysed for variable diffusion coefficient instead of for a constant value of diffusivity. This paper presents a simple method for graphical analysis of concentration gradients in solids to determine the diffusion coefficient as a function of concentration.

Consideration is given to problems encountered in extrapolation of data. It is shown that, if relative values of diffusion coefficient is the objects of consideration, no great need exists for exacting extrapolation. Two extrapolations are employed on any given functional model; the results of one extrapolation are greater, while those of the other arc less than the results predicted by the model.