Microstructure and Mechanical Properties of Ni45/Y Coatings by Laser Directed Energy Deposition (L-Ded)

Abstract

In order to improve the wear resistance and impact resistance of mechanical components, Ni45 powder and Y powder were used to prepare the coatings by laser directed energy deposition (L-DED). Microstructure and elements of the coatings were performed using SEM and EDS. A high speed camera was used to analyze the morphology of molten pool during the cladding process. Wear resistance and impact resistance of coatings were tested by wear and impact testing machine. Due to the oxidation reaction of Y in the molten pool, a large amount of thermal energy is released, which makes the molten pool have a faster flow rate. When the Y addition≤0.8 wt.%, the flow rate of the Y element molten pool increases rapidly. When Y is added > 0.8 wt.%, the flow rate of the melt pool increases slowly. The results show that Y can inhibit the growth of crystal grain and can be used as a heterogeneous nuclear particle to increase nuclear rate. Among them, the microstructure of the coating with 0.8 wt.% Y was more Ni45 significantly refined. Y caused the coating to precipitate more rich Cr hard phase and intermetallic compounds, which increases the abrasion resistance and the impact performance. The wear rate of 0.8 wt.% Y coating was 31.97% lower than that of Ni45 coating. The impact toughness was only 11.01% higher than that Ni45 coating.

Keywords: Laser cladding, Y element, Microstructure, Wear resistance, Impact resistance