Abstract: High-current pulsed electron beam(HCPEB) treatment is applied on a nickel-based superalloy GH4169. The microstructural changes induced by the pulsed electron beam irradiation are investigated in detail by X-ray diffraction, scanning electron microscopy(SEM) and transmission electron microscopy(TEM) together with their corrosion property. The experimental results indicate that the irradiated surfaces are melted and many craters are formed, while the density of craters shows a significant reduction with the increasing number of HCPEB irradiation. The second phase particles are eliminated with the eruption of the craters, leading to the surafce purification. After the HCPEB irradiation, the formation of a melted layer with depth of about 3-5 μm on the irradiated surface is observed. Furthermore, nanocrystals with the size of 100 nm are also formed in the melted region. Microstructural analysis shows the severe plastic deformationtion, high density of dislocations, as well as large quantities of deformation twins in the irradiated surface. Consequently, the corrosion resistance of the nickel-based superalloy GH4169 is significantly improved by HCPEB treatments. The surface purification effect induced by the HCPEB treatment, nanostructured surface melted layer along with high density of crystal defects which promote the formation of surface passivation layer, are responsible for the improvement in corrosion resistance.

Key words: corrosion resistance, high-current pulsed electron beam(HCPEB), nanocrystals, nickel-based superalloy GH4169, surface craters