Study on precipitation and corrosion behavior of Al-1.0Mg-0.6Si(-0.3Cu) alloys by Sn addition modification

Abstract

The effect of Sn and Cu addition on precipitation and corrosion behavior of Al-1.0Mg-0.6Si alloy are investigated using the hardness, electrochemical measurements, intergranular corrosion (IGC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicated that the peak-aged hardness of Al-1.0Mg-0.6Si (-Cu) alloy were enhanced by the addition of Sn, which is related to the acceleration of precipitation. Although the IGC of Al-1.0Mg-Si alloy is not generated by the addition of Sn, the degree of pitting corrosion will be alleviated. The additions of Cu alone increase the susceptibility of IGC. The susceptibility of IGC of Al-1.0Mg-0.6Si alloy can further be increased by joint addition of Sn and Cu, which is related to microstructure evolution of grain boundary. The increase in the width of precipitation free zone (PFZ) and distribution of continuous Q phase at grain boundary to from micro-battery accelerates the susceptibility of intergranular corrosion.