A comprehensive review on the rare earth elements improving microstructure and properties of laser cladded coatings

Adding rare earth element powder to the cladding powder can effectively control the microstructure of the laser cladded coating, improving the forming quality and relevant properties of the cladded coating. This article reviews the effects of adding rare earth elements on the preparation of laser cladded iron-based coatings, nickel-based coatings, cobalt-based coatings, and high-entropy alloys coatings. This article briefly introduces the influence of rare earth elements on the fluidity of the melt pool, grain refinement, and the interfacial bonding between the cladded coating and the substrate. The mechanism of rare earth elements refining the microstructure of the cladded coating was emphasized, including providing more nucleation sites and the dragging effect of rare earth atoms on grain boundary movement. The reasons for how rare earth elements suppress defects such as pores and cracks have been analyzed. The influence of the types, contents, and sizes of rare earth elements on hardness, wear resistance, and corrosion resistance has been investigated. Finally, the challenges of using rare earth element powders for laser cladded coating modification in industrial production have been analyzed, and the impact of rare earth modified laser cladded coatings has been summarized and discussed. • A comprehensive review on the effect of the rare earth elements on improving microstructure and properties of laser cladded coatings was provided. • The rare earth elements can promote metallurgical bonding and suppress the occurrence of defects such as pores. • The future research and development direction of laser cladding is prospected.