Laser powder bed fusion (LPBF) is a powder bed based additive manufacturing (AM) technology which is increasingly used to produce prototypes, models or products. Due to the layer-by-layer build-up of the parts, a high degree of geometric freedom is possible without the need for special tools or molds, enabling cost- and time-efficient manufacturing of complex parts. LPBF is one of the most common AM processes used for the fabrication of metallic parts by selectively melting and fusing metal powders with a high-energy laser beam according to the 3D computer-aided-design (CAD) model of the part. Increasing usage of LPBF opens it up for new fields of application. For instance, metal-matrix-composites (MMCs) are commonly used in high-strength or light-weight applications and tooling.
Aluminum/SiC metal-matrix-composites have been successfully integrated in aerospace and automotive fields due to their high specific strength, excellent thermal conductivity and strong wear resistance. However, traditional manufacturing, such as casting or powder metallurgy, limits the possible geometrical shapes and functionality of the products, which would be significantly improved using AM.
In the present work, commercially available AlSi10Mg and SiC powders are mixed in a tumble mixer, varying between 5, 15 and 25 vol.% SiC. Before the LPBF experiments were conducted, thermodynamic simulations were performed to determine possible resulting phases. Afterwards a range of process parameters was chosen to evaluate the manufacturability of the powder mixture. The resulting samples were characterized by various properties, such as porosity, microstructure and resulting phases. In addition, the correlation between the used energy density and the retained SiC particles in the samples was investigated. It is shown, that SiC can get dissolved due to high absorption of the laser energy which results in the formation of the phase Al4SiC4.