Galfan (Zn-5Al-RE) coating is widely used in high-strength steel wires. The effects of cooling rate and the adulteration of erbium (Er) on the microstructure and corrosion resistance of Zn-5Al alloys were investigated in this study. The results show that the Zn-5Al alloy is made up of the primary η-Zn phase and eutectic structure at a high cooling rate. As the cooling rate decreases, the corrosion current firstly increased and then decreased due to decrease of the primary η-Zn content, the appearance and grew of α-Al phase. Moreover, the addition of Er leads to the formation of Er-containing intermetallic compounds in the Zn-5Al alloy, reducing the size of the primary η-Zn and α-Al phase, decreasing the corrosion current density, and improving the density and compactness of the corrosion product.

In this paper, the effect of Er on the hot cracking behaviour of Al-5Cu alloy is investigated by the means of wedge moulds, differential hot analyzer, optical microscope, and scanning electron microscope. The results show that the percentage of intergranular low-melting-point eutectic structure is increased by approximately 8% on average per 0.3 wt-% Er additions. The increase of low-melting-point eutectic structure enhances the fluidity of the liquid film in the late solidification stage, resulting in the improvement of the hot cracking resistance of the alloy. Moreover, the Al-5Cu-0.6Er alloy has the best hot cracking resistance under wedge-shaped copper casting experiments.