Microstructure regulation and reinforcement mechanisms of ultrafine TiC/Fe55 composite coatings via laser melting deposition

Abstract

The interfacial strength of phases are the main challenges that limit the service performance of metal matrix composites. In this paper, the influence mechanism of the ultrafine TiC particles introduced through both in-situ and external methods on the microstructure evolution, interfacial structure, phases distribution and wear resistance of Fe-based composite coatings by laser melting deposition were comprehensively investigated. It was found that the TiC particle in all prepared coatings was ultrafine scale with a pure interface. Particularly, the TiC particle added by the external method was presented as a composite structure in which the ex-situ TiC was wrapped with the in-situ TiC. For the in-situ method, as the (Ti + C) content increased (5–15 wt.%), the TiC particle changed from blocky to petal shape, and the wear volume was decreased and then increased. Compared with the adding of 10 wt.% nano-TiC externally, the coating with adding 10 wt.% (Ti + C) presented with greater wear resistant for its higher TiC content. The blocky TiC particles was beneficial to deflecting cracks and serving as wear-resistant skeletons due to the great interfacial bonding strength. This study provides a guidance for the preparation of high-performance Fe-based wear-resistant coatings for both newborn and remanufactured equipment parts.

Keywords

• Laser melting deposition
• Ultrafine TiC particles
• Interfacial structure
• Microstructure evolution
• Wear resistance