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In this study, a 10 wt% SiC-reinforced AlSi10Mg-based composites is prepared by selective laser melting (SLM) process. The effect of laser linear energy density on phase morphology, microstructure, and mechanical properties of AlSi10Mg-10SiC composite is investigated. There is relatively higher density, no obvious pores and cracks in the SLM-fabricated AlSi10Mg-10SiC composites with laser linear energy densities ranging from 90.64 J/mm3 to 104.16 J/mm3. The high laser linear energy density promotes the in-situ reaction between SiC particle and Al melt in the melt pool, the Al4SiC4 phase forms during SLM fabrication process. Driven by Marangoni convection, the fine SiC particles and Al4SiC4 phase distributes uniformly. When the laser linear energy density is 104.16 J/mm3, the composite exhibits the highest average microhardness of 208.5 HV0.1. When the laser linear energy density is 90.64 J/mm3, the composite displays the highest yield strength and modulus with values of 408 MPa and 90 Gpa, respectively. During the deformation process of tensile test, the higher modulus SiC particles could withstand greater load transfer, which improves the modulus and yield strength of the composites.

In this study, seven AlSi10Mg bulks with different construction angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) were fabricated by selective laser melting (SLM). The effects of different construction angles on the microstructure and mechanical properties of AlSi10Mg alloys were investigated. Increasing the construction angle changed the laser track segments from an ellipse to a semi-ellipse and then to fish-scale, specifically again from a semi-ellipse to an ellipse, due to the decrease of the laser radiation area. Meanwhile, the grains in the vertical planes changed from columnar grains to irregularly arranged grains, and then to equiaxed grains. The 45° sample exhibited the highest hardness of 154.44 HV0.1. The 60° sample had a good combination of strength and plasticity with a tensile strength of 463.54 MPa, yield strength of 283.37 MPa, and elongation of 9.25%. The observed mechanical property anisotropy of the current AlSi10Mg alloy was a result of the pores, equiaxed grain structure, ultra-fine equiaxed sub-grains, and working hardening. In addition, the difference in the sample microstructures was attributed to the construction angles and deposited layer area.

A Ni-coated graphene (Ni-Gr) reinforced Inconel 625 composite was prepared by selective laser melting. The microstructure of the composite exhibited random aligned columnar dendrites due to the addition of Ni-Gr. The Ni-Gr defects were alleviated under high-intensity laser-beam irradiation. The Micro-CT showed that the pore density increased by 46% of Inconel 625 due to the addition of Ni-Gr. The flaky, open-ring Ni-Gr appeared due to the action of Marangoni convection and the surface tension. Furthermore, the addition of Ni-Gr improved the diffusion capacity of the friction heat. Inconel 625 composite displayed tiny bits of oxidized debris.