Effects of minor Y, Zr and Er addition on microstructure and properties of Al-5Cu-0.4Mn alloy

The effect of different contents of Y, Zr and Er on microstructure and properties of Al-5Cu-0.4Mn alloy was investigated. T6 heat treatment, OM, SEM and EDS methods were applied to the alloy. The results showed that fluidity and elongation of alloy adding Y, Zr and Er were improved, while with the increase of addition amounts, θ phase increased and grains were trended to grow up gradually. The Al-5Cu-0.4Mn alloy presented the maxed style of ductile and brittle fracture. After T6 heat treatment, the precipitation amounts of θ phase decreased dramatically and tensile strength and hardness significantly increased. Especially when addition contents were among 0.1-0.3wt.%, tensile strength and hardness of heat-treated alloy increased greatly, almost doubled as that of the as-cast state. The tensile strength reached its maximum of 378.43 MPa when the addition amount was 0.3wt.%. With the further increase of addition amounts, the elongation deteriorated and the proportion of ductile fracture reduced due to the limited dispersion strengthening effect of θ phase and Al8Cu4Er. It demonstrated that addition of 0.1-0.3wt.% Y, Zr and Er would generate positive effects and influences on Al-5Cu-0.4Mn alloy, which is significant for optimizing components and improving properties of Al-5Cu-0.4Mn alloy