Correlation of surface Volta potential with galvanic corrosion initiation sites in solid-state welded Ti-Cu bimetal using AFM-SKPFM

This study aims to correlate the microstructure and Volta potential distribution of Ti-Cu welded bimetal to its corrosion initiation sites, using AFM-SKPFM, and SEM-EDS. Local melted zones with Ti-Cu intermetallic precipitates in weld interface and in Cu matrix showed different Volta potential values in comparison with those of Ti and Cu regions. SKPFM revealed that Cu region has a higher Volta potential than that of Ti region. AFM and microstructural images after immersion in corrosive media proved the presence of a galvanic cell. Corrosion mainly extends on Cu side due to the increasing growth of Ti passive film.