Surface chromium alloying and high temperature oxidation resistance of nickel-based superalloy gh3039 under high current pulsed electron beam

The work aims to improve the high temperature resistance method of GH3039 alloy. Chromium (Cr) was coated on GH3039 alloy, and the surface of the alloy was treated by high-current pulsed electron beam (HCPEB). After treatment, X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) were used to observe and analyze the surface to compare the changes of phase and microstructure before and after HCPEB alloying. At the same time, the oxidation kinetics and oxidation mechanism before and after HCPEB alloying were investigated at a constant temperature of 850 ℃. Slip bands were formed on the surface of the alloy after HCPEB irradiation, and the grain size was obviously refined. Particularly, nanocrystalline structure with a size of about 100 nm was formed in the samples irradiated for 30 times. From the oxidation resistance test at constant temperature, the oxidation weight gain of the original sample was the largest after 100 h, and the oxide film was relatively thick, about 6 μm, with holes and cracks, and the matrix underwent serious internal oxidation. The oxidation weight gain of 30-implused samples was the smallest and the thickness of the oxide film was about 3 μm, mainly composed of Cr2O3. Moreover, Cr2O3 oxide film presented continuous growth trend and had compact structure without peeling, which played a protective role on the matrix. HCPEB irradiation can melt Cr atoms into the surface of GH3039 alloy and rapidly realize the surface alloying of Cr. The high temperature oxidation resistance of GH3039 alloy is improved by increasing the content of Cr on the alloy surface and promoting the diffusion of elements by the micro-structure. © 2020, Chongqing Wujiu Periodicals Press. All rights reserved.