Effect of Zn Incorporation on the Evolution of Texture, Strain, Grain Boundary Constitution, and Corrosion Behavior of Electrodeposited SnZn Coatings

Corrosion behavior of electrodeposited SnZn coatings with varying Zn content (5, 12, 17, and 23 wt pct) was correlated with the texture, grain boundary constitution, and strain in the matrix Sn phase. Pristine Sn coating (without Zn) exhibited the highest corrosion resistance due to highest fraction of low-angle grain boundaries (LAGBs) and lowest coating strain. Upon Zn incorporation, the coating corrosion resistance first decreased until Sn-12 wt pct Zn and then increased till Sn-23 wt pct Zn. The lower corrosion resistance of Sn-12 wt pct Zn coating was due to high strain and a higher fraction of high-energy high-angle grain boundaries (HAGBs). The high corrosion resistance of Sn-23 wt pct Zn coating was due to a higher fraction of low-energy coincidence site lattice boundaries (CSLs) and preferred low-energy (100) surface texture.

Automated summary

The corrosion behavior of electrodeposited SnZn coatings with different Zn contents was investigated in this study. The results showed that the pristine Sn coating without Zn exhibited the highest corrosion resistance, and the corrosion resistance of the coatings first decreased and then increased with the incorporation of Zn. This can be attributed to the increased strain and proportion of high-energy high-angle grain boundaries caused by Zn addition, resulting in a lower corrosion resistance. However, when the Zn content was 23 wt pct, the coating showed a higher corrosion resistance due to the increased proportion of low-energy coincidence site lattice boundaries and preferred low-energy (100) surface texture.