Mechanical properties, corrosion behavior and microstructure evolution of zinc and scandium co-strengthened 5xxx alloy

Nowadays, it is a challenge to improve the strength of 5xxx aluminium alloy while maintaining its distinctive properties. To address this, the Zn and Sc modified high strength 5xxx aluminium alloys with good intergranular corrosion resistance were prepared through chill casting, and the effects of minor Sc on mechanical properties, corrosion behavior and microstructure evolution of Al-5.0Mg-3.0Zn alloys were systematically investigated. The results show that the Sc containing alloy has high number density and small size of intragranular precipitates, combined with the solid solution strengthening of Sc and the Al3(Sc1–x,Zrx) second phase strengthening, the strength of Al-5.0Mg-3.0Zn-0.1Sc alloy is obviously enhanced. Meanwhile, the intergranular corrosion resistance of the Sc containing alloy is also improved due to the formation of a large number of low angle grain boundaries and the weakening of the continuity of precipitated phases along the grain boundaries.