Optimization of Electrical Conductivity and Hardness in Al-1Si Alloy Through Mg/Fe Alloying and Heat Treatment

In this study, a new kind of the Al-1Si-0.6Mg-0.2Fe alloy was fabricated by Mg, Fe alloying treatment and the influence mechanism of Mg, Fe on electrical conductivity (EC) and Vickers hardness (HV) of the Al-1Si alloy was analyzed by the combination of experiments and simulations. Results showed that during the solidification process, intermediate phase Al8FeMg3Si6 formed which can inhibit the growth of needle-like AlFeSi phase, resulting in a more refined distribution of AlFeSi particles and this is helpful to improve EC and HV simultaneously. According to the simulation results, Al-1Si-0.6Mg-0.2Fe generated the most Al8FeMg3Si6 and the corresponding EC and HV reached 48.5% IACS and 62.9 HV, respectively. Furthermore, during heat treatment process, AlFeSi can promote the nucleation of Mg2Si, reducing the elemental solution of Mg and Si. With 550 °C/2 h + 210 °C/24 h heat treatment, on the one hand, oversized needle-shaped AlFeSi fused to smaller particles and distributed more uniformly. On the other hand, more solid solution Si and Mg precipitated with form of Mg2Si. Finally, the EC and HV of Al-1Si-0.6Mg-0.2Fe improved to 54.5% IACS and 79.8 HV, achieving the simultaneous optimization of EC and HV. This can provide theoretical guidance for the preparation of high strength and high conductivity aluminum alloy.