Aluminium alloys are an important material system for structural parts and offer significant advantages for mass critical applications due to their low density and good mechanical properties. Additive manufacturing enables possibilities to save additional weight through design optimization. This makes additively manufactured aluminium alloys a promising solution to generate lightweight parts with excellent properties.
The near eutectic aluminium silicon alloys AlSi10Mg and AlSi12 are widely studied for use in additive manufacturing techniques today. Subject of the presented work is the possibility to fabricate hypereutectic AlSi alloys using Selective Laser Melting. These alloys exhibit decreasing density and increasing stiffness as the silicon content rises. Additionally the coefficient of thermal expansion is significantly lowered and can be adapted to match that of functional coatings. One inherent problem of powder bed based additive manufacturing processes is the presence of defects such as porosity, binding errors, impurities or variations in chemical composition. The negative impacts on material properties make these defects subject to intensive research. Aiming at the fabrication of parts for precision applications reliable properties are required. Hence, this work addresses the characterization of defects in additively manufactured hypereutectic AlSi alloys, which are caused by the fabrication process. Two- and three-dimensional measurements are performed to characterize the interior of solid parts with respect to porosity, cracks and microstructure. The chemical composition is determined by surface sensitive techniques (e.g. Energy Dispersive X-ray spectroscopy) and bulk methods, respectively.