Selective laser melting additive manufacturing of TiC/Inconel 718 bulk-form nanocomposites: Densification, microstructure, and performance

Selective laser melting (SLM) process was used to prepare the nanocrystalline titanium carbide (TiC)-reinforced Inconel 718 matrix bulk-form nanocomposites in the present study. An in-depth relationship between SLM process, microstructures, properties, and metallurgical mechanisms was established. The insufficient laser energy density (η) input limited the densification response of shaped parts due to the formation of either larger-sized pore chains or interlayer micropores. The densification of SLM-processed part increased to a near-full level as the applied η was properly settled. The TiC reinforcements generally experienced successive changes from severely agglomerated in a polygon shape to the uniformly distributed with smoothened and refined structures on increasing the applied η, while the columnar dendrite matrix exhibited strong epitaxial growth characteristic concurrently. The optimally prepared fully dense part achieved a high microhardness with a mean value of 419 HV0.2, a considerably low friction coefficient of 0.29, and attendant reduced wear rate of 2.69 × 10−4 mm3/N m in dry sliding wear tests. The improved densification response, SLM-inherent nonequilibrium metallurgical mechanisms with resultant uniformly dispersed reinforcement microstructures, and elevated microhardness were believed to be responsible for the enhancement of wear performance.