Influence of Ti addition on corrosion behavior of Sn–9Zn solder alloy

Recently, Sn–Zn alloys have emerged as cost-effective brazing materials for aluminum substrates, however, their limited corrosion resistance hinders their broader applications. Research has shown that Ti can significantly enhance the corrosion resistance of Sn–Zn alloys, but its full impact remains insufficiently explored. In this study, the electrochemical corrosion behavior of Sn–9Zn-xTi (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0 wt%) alloys in a 3.5 wt% NaCl solution, and the related corrosion mechanism, were extensively investigated. The results indicate that increasing Ti content leads to the sequential formation of (Ti, Zn)Sn 2 and Ti 2 Sn 3 . Meanwhile, the Zn-rich phase undergoes refinement, resulting in smaller corrosion pits that are more easily covered, effectively mitigating Cl − and OH − penetration into the matrix. However, when the Ti content exceeds 0.6 wt%, the refinement effect weakens, leading to larger corrosion pits and a subsequent reduction in corrosion resistance. Overall, the corrosion resistance of Sn–9Zn-xTi alloys is predominantly governed by the refinement of the Zn-rich phase. Among the studied alloys, Sn–9Zn-0.6Ti exhibits superior corrosion resistance, with total impedance increasing by approximately 1.7 times, and corrosion current density and passivation current density decreasing by 32.7% and 80.7%, respectively. These findings are pivotal for the development of new Sn–Zn solder alloys for corrosive environments.