Test of the Manning Vacancy-Flux Correction in α Cu-Zn

Manning has devised a treatment to correct self-diffusivities calculated from Kirkendall effect experiments by means of the Darken analysis for the flux of vacancies accompanying diffusion in a concentration gradient. An iterative technique has been developed which permits the Manning correction to be made directly on self-diffusivities determined from Kirkendall effect data. This technique has been applied to interdiffusion data in α Cu-Zn taken from the literature. The variation with zinc content of the DZn*/DCu* (self-diffusivity) ratios was found to be satisfactorily consistent with the ratios determined from literature data on radiotracer self-diffusivities only after the Manning correction was applied, in strong support of the validity of Manning's treatment. Individual values and the Arrhenius equation constants of the Manning-corrected self-diffusivities, on the other hand, remain inconsistent with comparable radiotracer data, perhaps because of the insufficient accuracy of the data so far obtained from Kirkendall effect experiments.