Densification behavior, microstructure evolution and fretting wear performance of in-situ hybrid strengthened Ti-based composite by laser powder-bed fusion

Abstract The in-situ TiB and TiC hybrid strengthened Ti-based composites were produced through laser powder-bed fusion (LPBF) of the B 4 C/Ti composite powder system. The influence of scan speed on the densification response, microstructural evolution, Vickers micro-hardness and fretting wear performance of LPBF-ed B 4 C/Ti composite parts has been evaluated. It revealed that the densification level of composite part was generally reduced as successively increased the scan speed from 600 mm/s to 1800 mm/s, while the microstructure was inversely refined with an initial enhancement of 459.3 HV 0.2 and a subsequent reduction of 361.2 HV 0.2 . As an appropriate scan speed of 1000 mm/s was used, the composite part exhibited a relatively low friction coefficient of 0.23, and was predominated by the fatigue wear mechanism with a low wear rate of 0.85 × 10 −13  m 3 /m, due to its high densification level and refined strengthen effects of hybrid reinforcements. However, as the scan speed increased to 1800 mm/s, the friction coefficient was measured with apparent fluctuations throughout the sliding process, and the abrasive wear accompanied with a severely adhesive wear was dominated with a high wear rate of 6.88 × 10 −13  m 3 /m, ascribing to its further low densification level and Vickers micro-hardness.