The effect of Y2O3 nanoparticle addition on the microstructure and high-temperature corrosion resistance of IN718 deposited by extreme high-speed laser cladding

The microstructural evolution and 700 °C high temperature corrosion resistance of Y2O3/IN718 composite coatings with different Y2O3 contents (0, 0.5, 1.0, 1.5, 2.0, and 3.0 wt%) fabricated by extreme high-speed laser cladding (EHLC) were investigated. The results showed that the addition of 1.0 wt% Y2O3 nanoparticles to IN718 could effectively reduce the internal porosity of the specimen, reduce crack initiation, refine the grain size, and improve the high-temperature corrosion resistance. The roughness Ra was reduced by 25.9 %, from 23.93 μm to 17.73 μm, and the average grain size was reduced by 39.5 %, from 47.32 μm to 28.62 μm. The result is due to the reduction in surface roughness and porosity of the specimen after the addition of Y2O3, which forms new nucleation sites at grain boundaries, resulting in surrounding lattice distortion and grain refinement.