Study on corrosion behavior of β-Sn and intermetallic compounds phases in SAC305 alloy by in-situ EC-AFM and first-principles calculation

Abstract This work studies the corrosion behavior of β-Sn and intermetallic compounds (IMCs) in Sn96.5Ag3.0Cu0.5 (SAC305) alloy through micro-structure observation, in-situ electrochemical technique and first-principles calculation. The results show that corrosion behavior of SAC305 is affected by galvanic corrosion, electronic structure and material microstructure. The Volta potential difference between Cu6Sn5, Ag3Sn and Sn is up to 234 and 174 mV. The length percentage of high angle grain boundaries (HAGBs) for β-Sn and eutectic phase is 11.61 % and 35.18 %. The calculated electronic density of state explains the corrosion behavior of SAC305 from corrosion kinetics perspective. The corresponding corrosion failure mechanism is proposed.