Investigation of the Microstructure and High-Temperature Performance of Laser-Clad Ni50(AlNbTiV)50-xY2O3 Complex-Concentrated Alloy Composite Coatings

This study prepares Ni50(AlNbTiV)50-xY2O3 complex concentrated alloy composite coatings and analyzes their microstructure, phase composition, and high-temperature performance. The results indicate that each coating is composed of FCC phases, including γ-FeNi, Ni3Al, and Ni3(Al, Ti), as well as BCC phases such as Ni3Nb and Ni3Ti. With increasing Y2O3 content, the lamellar structure in the inter-dendritic regions of the coatings first decreases and then increases. The wear mechanism of the coating without Y2O3 addition under high-temperature conditions involves the combined effects of abrasive wear and adhesive wear. The coating with a 0.6 wt.% addition exhibits the smallest cracks and the lowest oxidation rate in high-temperature oxidation and thermal shock tests, with the oxidation weight gain reduced by 26.2% compared to the coating without Y2O3 addition. The abrasive and adhesive wear of this coating is mitigated, and the average friction coefficient and mass loss are decreased. When the mass fraction of Y2O3 is 0.4 wt.%, the coating structure shows a significant refinement effect and exhibits the best performance in tensile strength and high-temperature friction and wear tests.