Fig. 1. The morphology of the corroded anode. (a) Surface morphology by OM. (b) Surface morphology by SEM. (c) Subsurface morphology by SEM.

Fig. 2. (a) The cross section morphology and (b) C, (c) O, (d) F, (e) Cu, (f) Al element distributions of the corroded anode.

Fig. 3. The surface morphologies of the corroded cathode by (a) OM and (b) SEM.

Fig. 4. (a) The cross section morphology and (b) C, (c) O, (d) F, (e) Cu, (f) Zn element distributions of the corroded cathode.

Fig. 5. The morphologies of (a) the flakes generated by the anode and (b) the particles generated by the cathode.

Fig. 6. The trace elements distribution of a copper part. (a) Surface content ${>}$50 ppm. (b) Surface content ${<}$50 ppm.

Fig. 7. The distribution diagram of reaction layers and elements of the corroded electrodes.