Microstructure and mechanical properties of Al-Cu alloys fabricated by selective laser melting of powder mixtures

Abstract Selective laser melting was used to in-situ fabricate Al-xCu (x = 4.5, 6, 20, 33 and 40 wt%) samples from mixtures of Al-4.5Cu/Cu powders. The insufficient Cu solute diffusion during the layer-by-layer processing results in an inhomogeneous microstructure around the introduced Cu powders. The boundaries between the molten pools of all alloys display different microstructural characteristics, indicating the occurrence of both high- and low-cooling-rate zones as well as heat-affected zones. With increasing Cu content, the Al2Cu phase in the alloys increases, improving the strength of the material. Al-33Cu with a nano-eutectic microstructure exhibits the highest compressive strength exceeding 1000 MPa.