Laser cladding of NiCrCoFeNbMoX high-entropy alloy to increase resistance to corrosion of gas turbine blades

Abstract

To improve the corrosion resistance of gas turbine blades that work in a salty and humid environment, NiCrCoFeNbMoX (X = 0,0.25,0.5,0.75,1) high entropy alloy (HEA) was deposited on GTD-111 superalloy by laser cladding. The results showed that with the increase of Mo, the volume fraction of Laves and eutectic phases increases, and the FCC phase decreases. An increase in the Laves phase shows an increase in the corrosion resistance of the above alloy system. In the meantime, NiCrCoFeNbMo0.75 HEA showed the highest corrosion resistance due to showing the highest self-corrosion potential and the lowest self-corrosion current density. The increase of the Laves phase and the reduction of the FCC phase were the most important factors of corrosion resistance. The NiCrCoFeNbMo1 system showed a lower corrosion resistance than the NiCrCoFeNbMo0.75 HEA due to the creation of fine eutectics. The results of hot corrosion also showed that NiCrCoFeNbMo0.75 coating has the highest resistance to hot corrosion in 90 wt% Na2SO4-10 wt% NaCl at 750 °C due to the uniform distribution of MoO3.