Effect of electric field treatment on intercrystalline corrosion of nickel-based superalloy

Electric field treatment was performed on one of nickel-based superalloy as heat shield used in aeroengine and the effects of electric field treatment on the microstructure and intercrystalline corrosion behavior were investigated. The results show that the intercrystalline corrosion resistance is improved by the electric field treatment and the intercrystalline corrosion rate decreases with the increasing treatment time. The intercrystalline corrosion rate is 65.26 mma-1 when the alloy is treated by electric field under the condition of 820C and 4 kV/cm for 10 h, and the decreasing extent reaches 25.25% compared with the alloy untreated. The formation and growth of the annealing twins during the electric field treatment cause the redistribution of atoms of the crossings between the original high angle grain boundaries and the annealing twins. With the increasing electric field treatment time, a large amount of original high angle grain boundaries are replaced and the continuous distribution of depletion network of the alloying element is separated, which leads to the retardation of the corrosion ditches to go forward. The intercrystalline corrosion resistance of the superalloy is improved due to the improvement of corrosion behavior of the grain boundary.