Nowadays, the composition uniformity and the interfacial bonding strength of phases are the main challenges that limit the service performance of metal matrix composites (MMCs) of laser cladding. In this paper, the affect mechanism of the ultrafine TiC particles introduced through both in-situ and external methods on the microstructure, microhardness, and wear resistance of Fe-based composite coatings were comprehensively investigated. It found that the TiC particle in all prepared composite coatings was ultrafine scale with a pure interface and uniform distribution. Compared with the adding of TiC externally, the Fe-based composite coating with the in-situ TiC particles presented with higher ultrafine TiC content and greater wear resistant. For the in-situ synthesis method, as the (Ti+C) content increased (5 wt.% to 15 wt.%), the morphology of the ultrafine TiC particle gradually changed from blocky to petal shape accompanied by the increased TiC content and size, and the wear volume was decreased and then increased. The TS2 coating with adding 10 wt.% (Ti+C) showed the best wear resistance, in which the wear volume is decreased by about 77.4% compared to the original Fe55 coating. In particular, the microstructure and wear behavior of Fe-based composite coatings with adding 10 wt.% (Ti+C) (TS2, in-situ) and 10 wt.% nano-TiC (TD2, externally) were compared and analyzed. The TS2 coating contained 8.11 wt.% TiC, while the TD2 coating contained 4.59 wt.% TiC, which results in the lower wear volume of the TS2 coating. Ultrafine blocky TiC particles was beneficial to deflecting cracks and wear-resistant skeleton, which played a crucial role in improving wear resistance. This study provides a guidance for the preparation of high-performance Fe-based wear-resistant coatings for both newborn and remanufactured equipment parts.

Laser cladding; Ultrafine TiC particles; Interfacial structure; Microstructure evolution; Wear resistance