Hot corrosion behavior of a novel TiC/GTD222 nickel-based composite prepared by selective laser melting

Abstract

In this study, a novel TiC/GTD222 nickel-based composite with enhanced hot corrosion resistance was designed by incorporating appropriate amounts of C, Al, and Ti elements into the GTD222 superalloy. The composite was successfully prepared using the selective laser melting (SLM) technique. The hot corrosion behavior of GTD222 superalloy and the TiC/GTD222 composite in a salt mixture of 75% Na2SO4 + 25% NaCl (wt%) at 900 °C was systematically studied. The results show that the TiC/GTD222 composite exhibits much better hot corrosion resistance than the GTD222 superalloy. This is because a continuous and dense double-layer oxide film is formed in the composite (The inner layer is TiO2 and the outer layer is Cr2O3), while oxide film of the superalloy is loose and porous, and has a discontinuous TiO2 and Al2O3 distribution. The adding alloy elements can promote the formation of more γ' phase and TiC particles in the TiC/GTD222 composite, and also result in the refined grain and formation of more dislocations. The above microstructures increase the diffusion channels of elements, and the higher contents of Al and Ti can enhance the diffusion potential energy of these elements, leading to the formation of continuous and dense double-layer oxide film of the composite. This work provides new ideas for the design of additive manufactured superalloy.