Corrosion resistance of NbCrFeNiCoMoX coating applied by laser cladding on GTD-111 superalloy: Application of gas turbine blade

Abstract

NbCrFeNiCoMoX (X = 0,0.25,0.5,0.75,1) high entropy alloys (HEAs) were laser cladded on GTD-111 Superalloy specimens as coating to investigate the effect of Mo molar ratio on corrosion behavior of coated blades in NaCl 3.5% solution. The results showed that the corrosion resistance increases with increasing Mo content up to 0.75. This was attributed to the reduction of the FCC phase and the increase in the content of eutectic and Laves phases. Meanwhile, at high values of Mo0.75, a decrease in corrosion resistance was detected due to an increase in the fineness of the eutectic phase. Appropriate volume fraction of Laves (68.3%) and eutectic (11.4%) phases in HEA0.75 coating caused the lowest corrosion current density (1.9541 ×10−6 A.cm−2) and the highest corrosion potential (−0.224 V). Cr and Mo oxides, by creating a protective layer against uniform corrosion and pitting corrosion, were introduced as the most important reasons for increasing corrosion resistance.