Al-3.5Cu-1.5Mg-1Si alloy and related materials produced by selective laser melting

Selective laser melting (SLM) is an additive manufacturing technology. In this thesis, a heat-treatable Al-3.5Cu-1.5Mg-1Si alloy and related materials (composites and hybrid materials) have been successfully fabricated by selective laser melting and characterized in terms of densification, microstructure, heat treatment, mechanical properties as well as tribological and corrosion behavior. Firstly, the fully dense SLM Al-Cu-Mg-Si alloy was fabricated by SLM successfully. The alloy shows a higher yield strength than SLM Al-12Si alloy, and lower wear resistance and corrosion rate than commercial 2024 alloy before and after T6 heat treatment. Secondly, with the aim of designing new alloy compositions and to examine the phases and microstructures of SLM Al-Cu alloys and to correlate their microstructures with the observed mechanical properties, Al-xCu (x = 4.5, 6, 20, 33 and 40 wt. %) alloys have been synthesized in-situ by SLM from mixtures of Al-4.5Cu and Cu powders. The results indicate that the insufficient Cu solute diffusion during the layer-by-layer processing results in an inhomogeneous microstructure around the introduced Cu powders. With increasing Cu content, the Al2Cu phase in the alloys increases improving the strength of the material. These results show that powder mixtures can be used for the synthesis of SLM composites but the reaction between the matrix and the second-phase should be considered carefully. Thirdly, the TiB2/Al-Cu-Mg-Si composite was also designed and fabricated successfully by SLM and it shows a higher strength than the unreinforced SLM alloy before and after T6 heat treatment. Finally, an Al-12Si/Al-3.5Cu-1.5Mg-1Si hybrid with a good interface was fabricated successfully. This hybrid alloy shows a good yield strength and elongation at room temperature, indicating an effective potential of selective laser melting in the field of hybrid manufacturing