Effect of Ce content on the microstructure and mechanical properties of squeeze-cast Al–5Mg-2.2Si-0.6Mn alloys

Abstract

The effect of Ce in amount of 0–0.5 wt.% on the microstructure and mechanical properties of the squeeze-cast Al–5Mg-2.2Si-0.6Mn alloys produced by squeeze casting technique was explored. The microstructure was observed by optical microscopy and scanning electron microscopy. The hardness and mechanical properties of the alloys were measured by Vickers hardness and tensile test. The microstructure of the squeeze-cast Al–5Mg-2.2Si-0.6Mn alloys is composed mainly of α-Al, Al–Mg2Si eutectic cells, the bulky lath-shaped Al8CeMn4 phase, Al2Mn3 and Al5Mn2Si5 phases after Ce is added. The results show that the addition of Ce leads to the grain refinement, which can improve the mechanical properties. When adding superfluous Ce, the formation of coarse and brittle Al8CeMn4 phase seriously reduces the mechanical properties of the alloy. With the increase of Ce content, the secondary dendrite arm spacing of different alloys decreases first and then increases, hence the hardness and tensile properties increase first and then decrease. The most remarkable improvement in the mechanical properties was acquired in the alloy with 0.10 wt.% Ce addition, the hardness reaches 48.1 HV, the ultimate tensile strength, yield strength and elongation are 265.5 MPa, 185.8 MPa and 5.8%, respectively.