Microstructure Evolution and Mechanical Properties of TiC/Ti6Al4V Composite Fabricated via by Selective Laser Melting

TiC/Ti6Al4V composite is produced using selective laser melting (SLM). The study examines how varying process parameters influence the density, microstructure, and tensile properties of the composite. The findings reveal that using a laser power of 180 W and a scanning speed of 1000 mm/s achieve a composite density of up to 99.7%. The microstructure is primarily composed of acicular α’ martensite, unmelted carbon particles, and in-situ TiC phase. With an increase in laser energy density, the TiC phase morphology shifts from nanometer-sized granules to micron-sized dendritic phase. This transformation is mainly attributed to the cumulative effect of laser energy and the size effect of carbon particles. At a laser energy density of 133 J/mm³, the composite achieves maximum average microhardness and the tensile strength of 461 HV and 1367 MPa, respectively. Compared to the Ti6Al4V alloy, the average microhardness increased by about 34%, and the tensile strength by about 15%. These results underscore the role of TiC formation in enhancing the mechanical properties of the composite. Furthermore, the dissolution degree of carbon particles also indirectly influences the strength and microhardness of the composite.