Effects of different post-processing temperatures on the microstructure and mechanical properties of TiC-Ni cermets fabricated by selective laser melting

Abstract

Selective laser melting (SLM) combined with post-processing is a common method for fabricating complex-shaped cermets components. This study utilized SLM-fabricated samples and employed vacuum sintering as a post-processing technique to investigate the effects of different post-processing temperatures (1350 °C, 1375 °C, 1400 °C, 1425 °C, 1450 °C) on the microstructure and mechanical properties of TiC-35 wt% Ni cermets. The results showed that using SLM printing parameters of 240 W laser power and 300 mm/s scanning speed produced well-formed samples. As the sintering temperature increased, the sintering mechanism gradually transitioned from solid-phase sintering to liquid-phase sintering. Relative density, hardness, bending strength, and fracture toughness showed a trend of first increasing and then decreasing. At 1400 °C, peak values were achieved: 97.7 % relative density, 82.7 HRA hardness, 901.8 MPa bending strength, and 8.72 MPa·m¹/² fracture toughness. Beyond this temperature, excessive grain growth and an increase in the brittle Ni₃Ti phase led to a decline in mechanical properties. Vacuum sintering could be a promising post-processing technique for eliminating SLM-related defects and enhancing mechanical properties.