Effect of thermal treatments on the surface electrical conductivity of AlSi7Mg produced by laser powder bed fusion

In the last years, the production of hypoeutectic Al-Si waveguide components by metal additive manufacturing has gained increasing attention in the telecommunications industry. The performances of waveguide components are influenced primarily by dimensional tolerances, surface electrical conductivity, surface roughness, and dimensional accuracy. Among these properties, electrical conductivity is known to be strongly influenced by the structural and microstructural characteristics of the alloys. In this work, microstructural and structural properties of an hypoeutectic Al-Si alloy, namely the AlSi7Mg alloy, were studied using FESEM, DSC, and XRD to understand how different thermal treatments (stress relieving, T5, and T6) affect the surface electrical conductivity. In the end, the most suitable thermal treatment to be applied to this alloy to maximize its electrical conductivity and, therefore, its appeal for microwave waveguide components is identified.