Laser additive manufacturing of nano-TiC reinforced Ni-based nanocomposites with tailored microstructure and performance

Laser additive manufacturing has demonstrated a promising capability in the simultaneous formation of high-performance nanocomposites with unique microstructure characteristics. The present work studied the densification, microstructure and mechanical properties of nano-TiC reinforced Inconel 718 composites processed by selective laser melting (SLM) with variation of laser energy linear density (E). It revealed that a fully dense TiC/Inconel 718 part was fabricated at a proper E of 300 J/m. On increasing E from 225 to 300 J/m, the nano-TiC reinforcement experienced severe agglomeration to uniform distribution along the grain boundaries and inside the grains of matrix. The morphologies of nano-particles transferred from irregular polygonal to near-spherical shape. The presence of nano-TiC could also accelerate the refinement of columnar dendrites spacing of gamma matrix. A high nanohardness of 4.48 GPa, a low coefficient of friction of 0.36 and resultant low wear rate of 3.83 x 10(-4) mm(3)/N.m were obtained at E of 300 J/m, showing a significantly improved mechanical performance compared to the SLM-processed unreinforced nickel-based alloys.