Effect of Process Parameters on the Microstructure and Mechanical Properties of SiC/Ti6Al4V Composites Manufactured by Selective Laser Melting

This study aims to optimize the process and performance of selective laser melting (SLM) of SiC/Ti6Al4V composite materials by investigating seven different SLM process parameters at varying laser energy densities. The effects of laser energy density on the microstructure, mechanical properties, and strengthening mechanisms of the composite material were systematically investigated using X-ray diffraction (XRD), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and room-temperature tensile tests. The results indicate that laser energy density significantly influences the formability and mechanical properties of the SiC/Ti 6 Al 4 V composite material. At a laser energy density of 50 J/mm³, the sample exhibited a stable melt pool, minimized defects, and achieved the highest density, resulting in optimal tensile properties, including a yield strength of 1243 MPa and an elongation rate after fracture of 13.8%. Below 50 J/mm³, insufficient energy input resulted in incomplete powder fusion, causing defects such as porosity and spheroidization, which impaired mechanical performance. Conversely, when the energy density exceeded 50 J/mm³, excessive energy input led to increased metal evaporation and residual stress accumulation, causing pore formation and a decrease in material properties. The composite material's strengthening effect arises from the synergistic action of multiple mechanisms: SiC particles act as heterogeneous nucleation sites, refining the grain microstructure and enhancing the material's isotropy. During the SLM process, in-situ reactions between SiC and the Ti matrix generate Ti 5 Si 3 and TiC reinforcement phases. The strong interfacial bonding and crystallographic compatibility between Ti 5 Si 3 and the α-Ti matrix strengthens the material's mechanical property through dispersion and dislocation strengthening.