Microstructure Evolution of TiC/Inconel 718 Composites Prepared by Direct Energy Deposition

TiC/Inconel 718 alloys with different TiC contents are prepared by direct energy deposition technology. The influence of laser power on the microstructure evolution and mechanical properties of the specimens is investigated. According to the microstructure evolution and mechanical properties, it can be observed that the different TiC contents of specimens have the appropriate laser power. The excessive laser power could lead to the generation and coarsening of the Laves phase, and the increasing of dendrite spacing, which causes the formation of cracks. The appropriate laser powers are respectively 1800 and 2000 W when the TiC contents are 5 and 10 wt%. When the TiC content is 15 wt% and laser power is 2000 W, the good metallurgical bond and refined microstructure of the specimens without penetrating cracks are obtained. The penetrating cracks of the specimens have form when TiC content is 20 wt%, which indicates that the TiC maximum content of TiC/Inconel 718 composites should be less than 20 wt% when the laser power does not exceed 2000 W. With the increasing of laser power, the difference of theoretical density between actual density is reduced and the average hardness is not changed.