Effect of different heat treatments on the high temperature tensile behavior and electrical/thermal conductivity of HPDC castings in high recycled content AlSi10MnMg alloy

The growing need to reduce the carbon footprint of transportation is driving vehicle lightweighting using thin-walled aluminum high-pressure die casting (HPDC) components. Using recycled rather than primary aluminum i.e., from bauxite, further enhances sustainability by reducing energy consumption and emissions. Accordingly, also heat treatments (HTs) with limited energy demand and low risk of dimensional distortions and blistering, like annealing and direct artificial aging, are today preferred. Many HPDC vehicle components also undergo finishing treatments at similar temperatures, such as e-coating, or are exposed to elevate service temperatures that can affect their final properties. Therefore, assessing their strength and thermal management capabilities is critical. The present study investigates the effects of HTs on the high-temperature tensile strength and electrical/thermal conductivity of an automotive component produced from an AlSi10MnMg HPDC alloy with a high recycled content. The mechanical and functional properties are correlated with microstructural features, including the size, morphology, and interparticle spacing of eutectic silicon, as modified by HTs. In turn, fracture surfaces analysis reveals the relationship between microstructural changes and failure mechanisms. Results clearly show that silicon particles play a crucial role in determining the investigated properties, significantly influencing strength and conductivity. Moreover, despite being produced through recycling processes, the recycled alloy exhibits overall performance comparable to that of primary alloys. This confirms its potential for sustainable lightweight solutions without compromising properties. • Sustainable heat treatments enhance heat dissipation in recycled Al alloys. • Deep microstructural and SEM analysis reveal alloy behavior and failure modes. • Eutectic Si morphology and spacing affect electrical and thermal conductivity. • Experimental data confirm validity of Wiedemann–Franz and Smith–Palmer laws.