Hot Corrosion Behavior of a Novel Tic/Gtd222 Nickel-Based Composite Prepared by Selective Laser Melting

Abstract

In this work, a novel TiC/GTD222 nickel-based composite with excellent hot corrosion resistance was designed by increasing proper C, Al and Ti elements content in GTD222 superalloy, and successfully prepared by selective laser melting. 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 on the composite surface (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 γʹ phase and TiC particles in the TiC/GTD222 composite, and also result in the refiner 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.

Keywords: Key wards: Hot corrosion resistance, Nickel-based alloy, Selective laser melting