Corrosion behavior of Sn-3.0Ag-0.5Cu alloy under chlorine-containing thin electrolyte layers.

Graphical abstract Highlights • Sn-3.0Ag-0.5Cu alloy mainly showed local corrosion under thin electrolyte layers. • Intermetallic compounds and β-Sn crystal boundary boosted Cl− infiltration. • Adsorption of Cl− and OH− on surface oxides made local passivating film thin. • Corrosion products at pitting corrosion boundary region boosted pitting corrosion. Abstract Corrosion behavior of Sn-3.0Ag-0.5Cu lead-free solder alloy under chlorine-containing thin electrolyte layers is studied. The emphasis is laid on discussion about influences of addition of alloying elements, concentration of chloride ion and thickness of electrolyte layer on its corrosion behavior. Results indicate that: mainly local corrosion occurs to the alloy; Existence of intermetallic compounds and β-Sn crystal boundary facilitates the process of Cl− infiltration into the base and galvanic corrosion. Metal ions are accumulated in pitting corrosion region, and hydrolysis of metallic ions promotes the solution acidification and transverse development of pitting corrosion. [ABSTRACT FROM AUTHOR]