Understanding the non-monotonic variation in the corrosion rate of Sn-Ni coatings with Ni addition by the analysis of texture and grain boundary constitution of the matrix phase and spatial distribution of the intermetallic phase in the coating microstructure.

Sn-Ni coatings (0 - 13 wt.% Ni) were electrodeposited on mild steel. The highest ( R p = 18561.1 Ω·cm 2 ) and the lowest ( R p = 4756.7 Ω·cm 2 ) corrosion resistance was observed for Sn-6 wt.% Ni and Sn-13 wt.% Ni coating, respectively. Higher corrosion resistance of Sn-6 wt.% Ni coating was due to low energy (100) surface texture, low energy CSL boundaries and formation of Ni 3 Sn 4 phase at grain boundaries. Higher corrosion rate of Sn-13 wt.% Ni coating was due to highest fraction of high energy high angle grain boundaries, higher matrix strain and higher volume fraction of cathodic Ni 3 Sn 4 phase. • Sn-Ni coating (0-13 wt% Ni) were electrodeposited over mild steel. • Corrosion properties and coating texture was highly sensitive to the Ni content. • An optimum addition of Ni in Sn coating (6 wt.% Ni) yielded high corrosion resistance • High corrosion resistance at optimum Ni addition was due to Ni 3 Sn 4 intermetallic in the grain boundary region, low energy (100) surface texture and highest fraction of low energy CSL boundaries.