Selective laser melting of novel nanocomposites parts with enhanced tribological performance

Abstract

Selective laser melting (SLM) was applied to build the nanocrystalline TiC/Ti nanocomposites parts. The influence of linear laser energy density (λ) on densification, microstructures, microhardness, and tribological performance of SLM-processed parts was investigated. It showed that the densification rate of TiC/Ti parts remained above 97% using linear laser energy density λ≥600 J/m. A decrease in λ caused the balling effect and lowered densification. The TiC reinforcement in SLM-processed parts had unique microstructures distinctly different from the initial nanoparticle morphology. A proper decrease in λ led to the formation of the uniformly dispersed nanoscale lamellar TiC reinforcement. The SLM-processed parts had an enhanced microhardness of 566 HV0.2, a low average coefficient of friction (COF) of ~0.25 and a reduced wear rate of ~4×10−16 m3/(Nm) during dry sliding tests. The insufficient SLM densification at a low λ and the disappearance of nanoscale TiC reinforcement at a high λ generally lowered the tribological performance of SLM-processed TiC/Ti parts.