The effects of lanthanum on microstructure and electrochemical properties of Al-Zn-In based sacrificial anode alloys

In order to improve the non-uniform corrosion of Al-0.5Zn-0.03In-1Mg-0.05Ti alloys, Al-5Zn-0.03In-1Mg-0.05Ti-xLa (x = 0.3, 0.5 and 0.7 wt.%) alloys were developed. Microstructures and electrochemical properties of the alloys were investigated. The results show that the optimal microstructures and electrochemical properties are obtained in Al-5Zn-0.03In-1Mg-0.05Ti-0.5La alloy. The main precipitate phase is Al2LaZn2 particles. The excellent electrochemical properties of Al-5Zn-0.03In-1Mg-0.05Ti-0.5La alloy is mainly attributed to fine grains and grain boundaries containing fine Al2LaZn2 precipitates. At the same time the fine grains can improve the non-uniform corrosion of Al-0.5Zn-0.03In-1Mg-0.05Ti alloy.