The effect of the electromigration on the GB grooving kinetics is simulated by applying first a constant voltage difference (CVD) between electrodes, and assuming that surface drift-diffusion as well as the surface specific Gibbs free energy are isotropic.
Constant current condition is kept to the point of 95% cathode area reduction (voiding).
At this point in order to obtain the cathode drift regime, we have further continued our experiments by terminating the CVD condition after 95% reduction in the cathode contact area (or equivalent increase in specimen resistance), and switched on the constant current test (CCT) program by allowing the whole cathode area (the complete width, ) is exposed to the original applied electrostatic field intensity denoted by (or invariant), and then connecting two terminal nodes, which define the remaining part of the cathode contact area (5%), to form a fully-connected cathode contour.
There is a pronounce asymmetry in the profile. The windward side of the GB shows
an extra mass accumulation compared to the leeward side, which shows almost flat appearance.
Typical profile evolutions are given in figures 4 & 5 (x=5,50).
figure 4
