Jerky Motion of the Reaction Front during Discontinuous Dissolution in a Fe-13.5 at.% Zn Alloy.

This paper studies the go- and -stop movement of a receding reaction front (RF) during a discontinuous dissolution (DD) process. A special simulation procedure was applied for the DD reaction to predict a jerky motion of the RF. The Fe-13.5 at.% Zn alloy was selected in which go- and -stop behaviour was revealed in the form of characteristic lines (called "ghost lines") showing successive positions of receding RF. The results presented for the DD process are quite different from those relevant for the DP reaction at the same Fe-13.5 at.% Zn alloy in terms of go- and -stop motion and movement distance. For the presented case, the go- and -stop periods are relatively long and obtain an order of several dozen seconds, while for the DP reaction, it was only a few seconds. A similar conclusion was formulated after a comparison of the movement distance which, for the DD reaction, is usually longer by 1-2 orders of magnitude. The simulation results of the DD reaction indicate a good agreement with the experimental data presented in the literature for the same dissolution rate. It is necessary to emphasize that the simulation is the only source of data for z parameter changes during the -stop period of the DD reaction.