Influence of Post-Heat-Treatment Temperature on the Microstructural Evolution and Tribological Performance of Selective Laser Melting-Fabricated AlSi10Mg Alloy

Abstract Additive manufacturing of AlSi10Mg alloys enables lightweight, high-strength components, while the rapid solidification and thermal gradients inherent to selective laser melting (SLM) introduce non-equilibrium microstructures that require optimization through controlled thermal treatments. This study investigates the influence of post-heat-treatment temperature on the microstructural evolution, mechanical response, and tribological performance of SLM-fabricated AlSi10Mg alloy. The SLM-fabricated AlSi10Mg specimens were heat-treated at 300 °C, 400 °C, and 500 °C to examine temperature-dependent changes in phase composition, microstructure, hardness, and wear characteristics. Microstructural analyses using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy revealed that aging at 400 °C promotes the formation of uniformly distributed Si and Mg2Si precipitates within a refined α-Al matrix, resulting in a homogeneous cellular-dendritic morphology with minimal porosity. The 400 °C condition exhibited enhanced phase stability and optimal mechanical balance, maintaining a relative density above 99.3% and a microhardness of approximately 160 HV0.5. Tribological testing using a pin-on-disc setup demonstrated that samples heat-treated at 400 °C achieved the lowest wear-rate, improving by nearly 74% compared to the as-built condition, and the lowest coefficient of friction (≈22.8% reduction), attributed to the formation of a stable tribo-oxide layer. The heat treatment at 400 °C was identified as the optimal condition, providing superior wear resistance and stable frictional performance. These results establish a clear relationship between heat-treatment temperature, microstructural stability, and tribological behavior, supporting the development of standardized post-processing protocols for SLM-fabricated AlSi10Mg components.