Abstract
The Al-Si-Mg alloy is highly popular in the aluminum industry, and the Mg2Si/Al composites demonstrate extensive development prospects. However, the practical production of these composites still faces certain obstacles. In this study, L₃₂(4⁹) orthogonal experiments were conducted to systematically examine the impact of heat treatment conditions on 15%Mg₂Si/Al-8Si composites with 0.5%Sb modification. The microstructures of the as-cast alloys and heat-treated samples were studied using OM, XRD, DSC, SEM, EDS, and hardness tests. By conducting an orthogonal test, the influence of each factor was analyzed to quantify its magnitude and identify the optimal heat treatment process. The results showed that the hardness value of the alloy could be increased from 74.77 to 163.86 HV through heat treatment. Additionally, the average particle size of the initial Mg₂Si could be refined from 19.15 to 12.44 μm. Furthermore, the hardening mechanism of the heat treatment parameters was discussed in detail.

Key words
15%Mg₂Si/Al-8Si composites, orthogonal experiment, heat treatment, hardening mechanism

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