Microstructure Evolution and Property Regulation of Cocrninbx Laser Cladding Coatings

Abstract

The influence of different Nb on the microstructure evolution, properties of the CoCrNi laser cladding coating was investigated. With the increase of Nb addition, the eutectic structures showed a transition from planar crystals to cellular crystals to dendritic crystals. Besides, the eutectic lamellae gradually became dense. A large amount of Ni3Nb-HCP structure precipitates were precipitated in the coating with excessive Nb. The introduction of Nb brought about an increase in heterogeneous nucleation cores, which in turn significantly refined the grain size in the secondary remelting zone of the cladding coating. As the Nb content increased, the hardness of coatings gradually increased, but both wear resistance and corrosion resistance showed a trend of first increasing and then decreasing.

Keywords: CoCrNi medium-entropy alloys, Microstructure evolution, Wear resistance, Corrosion resistance