Achieving optimal strength-conductivity balance in cast Al-2.3Fe-Mg-Si alloys via Mg/Si ratio regulation

The Al-2.3Fe eutectic alloy is regarded as a promising substitute for Cu conductors in automotive motors owing to its excellent castability and low resistivity. However, its application is restricted by the mutually exclusive relationship between electrical conductivity and mechanical strength. The microstructure and mechanical properties of Al-2.3Fe alloy were modified through Mg/Si alloying combined with T6 heat treatment in this work, leading to the development of a high-performance cast Al-2.3Fe-Mg-Si alloy. In the Al-2.3Fe-0.40Mg-0.72Si (Mg/Si=0.56) alloy subjected to T6 treatment, an electrical conductivity of (52.5±0.6)% IACS is achieved, while the ultimate tensile strength is significantly enhanced to 309.5±5.6 MPa. The addition of Mg and Si brings about marked changes in the solidification process of the Al-2.3Fe alloy, resulting in considerable variations in both the morphology of the second phase and its phase constitution. The aging behavior of the alloy is governed by second phase and solid solubility. Through optimization of the Mg/Si ratio, the aging response can be effectively enhanced. At the ratio of Mg/Si=0.56, a balance is achieved between solid solubility and precipitation, while simultaneously minimizing the detrimental impact on electrical conductivity and reach the best mechanical properties and electrical conductivity in peak-aged Al-2.3Fe-xMg-ySi alloy. This work providing valuable insights for developing advanced conductor materials.