Effect of the Addition of Trace TiB2 Particles on the Microstructure and Properties of SLM-Formed AlSi10MgEffect of the Addition of Trace TiB2 Particles on the Microstructure and Properties of SLM-Formed AlSi10MgZhao, Jiang, Yang, Lin, Y. Zeng, Li, Y. Wang, G. Wang, L. Zeng, Hong, and Zhang

Nearly complete-density AlSi10Mg/TiB2 composites were successfully prepared using selective laser melting technology by adding 3 wt.% reinforcement and optimizing the parameters. Microstructure characterization and a microhardness test were conducted on the formed samples. As the laser energy density increased, the resulting density initially rose, reached a peak, and then declined (the highest peak value was 99.22%). Nearly fully dense specimens were eventually obtained. X-ray diffraction results showed that the increase in laser energy density reduced the interplanar spacing, and abundant Si atoms were dissolved to cause lattice distortion. Optical microscope and scanning electron microscope observations revealed that the microstructure of the matrix was fine and that a limited amount of Si particles precipitated from the grain boundaries. Moreover, the surface of the TiB2 reinforcement was smooth, and the TiB2 particles were uniformly distributed. The increase in microhardness may be ascribed to the combined effects of dislocation strengthening, fine-grain and Orowan strengthening, and load transfer.