Solute Concentration Profiles for Discontinuous Dissolution in Al-22 at. % Zn Alloy

The discontinuous dissolution reaction has been analyzed in an Al-22 at. % Zn alloy. A simulation method based on the Ziba-Pawowski equation has been used to determine the solute concentration profiles expected to form behind the receding cell boundary for various initial values of the solute concentration in the lamella at the / interface as well as the solute concentration in the newly formed solid solution at the tip of the lamella. A criterion for the applicability of the Ziba-Pawowski model has been formulated. The simulated profiles are in a very good agreement with the experimental ones obtained by using a special procedure involving in situ observation and high spatial X-ray measurements in a transmission electron microscope.