Microstructure evolution, mechanical properties, and strengthening mechanism of TiC reinforced Inconel 625 nanocomposites fabricated by selective laser melting

Abstract

Selective laser melting (SLM) at different laser fluences was used to fabricate a TiC/Inconel 625 (TiC/IN625) nanocomposites. The influence of laser fluence on surface morphology, microstructure evolution, and mechanical properties of the TiC/IN625 nanocomposites were studied. The surface morphology of the TiC/IN625 nanocomposites was affected by the applied laser fluence, and the surface morphology was optimal when the laser fluence was 208 J/mm3. The laser fluence influenced growth of the TiC/IN625 nanocomposites microstructure, ranging from insufficient growth (139 J/mm3) to sufficient growth (167 J/mm3) and refined columnar/cellular dendrites (208 J/mm3). A continuous and refined ring-like network structure with homogenously distributed reinforced TiC phases was obtained. Obvious grain refinement occurred in the TiC/IN625 nanocomposites because TiC nanoparticles acted as nuclei for heterogeneous nucleation. The TiC/IN625 nanocomposites printed at 208 J/mm3 exhibited 1219 MPa ultimate tensile strength and 31% fracture strain. The superior strength of the TiC/IN625 nanocomposites was attributed to dislocation strengthening, Orowan strengthening, grain refinement strengthening, and load-bearing strengthening.