Microstructures and high-temperature oxidation behavior of laser cladded NiCoCrAlYSi coating on Inconel 625 Ni-based superalloy modified via high current pulsed Electron beam

NiCoCrAlYSi coatings were prepared on the surface of nickel-based high-temperature alloys (Inconel 625) by laser cladding (LC) technique, and then the surface was modified by high current pulsed electron beam (HCPEB). The microstructural results indicate that metallurgical defects on the original surface, including micropores and elemental segregations were eliminated, and a remelted layer consisting of high density of cross slips and nanostructures was obtained. High-temperature oxidation resistance at 900 °C, 1000 °C and 1100 °C of the original coatings was investigated. When oxidized at 900 °C for 100 h, the original coating followed the linear growth law, and the TGO was mainly consisted of Al2O3. When oxidized at 1000 °C and 1100 °C for 100 h, the original coating followed the parabola law, and the TGO existed in a double-layer structure. After HCPEB irradiation, a rather stable, continuous, and slow-growing α-Al2O3 was formed on the surface after oxidation for 100 h at 1100 °C. The kinetic curves show that the growth rate of the TGO of the irradiated coatings was reduced by 43.9%, and the thickness was effectively decreased compared with the original sample. Thus, HCPEB technique is proved to be an effective method to improve the service life of laser cladding coatings.