Study On The Preparation And Hot Corrosion Behaviors Of Ni/Y₂O₃Coated Powder Dispersion Strengthened Nickel-based Superalloy

The development history and current research situation of nickel-based superalloywere summarized in this paper, and an idea of preparation of ODS nickel-based superalloyby powder metallurgy was put forward. The alloys’ mechanical properties such as relativedensity, microhardness and tensile strength were tested, high temperature hot corrosionbehavior, structure morphology and fracture morphology of alloys was discussed andanalyzed. The preparation process was continuously optimized in order to obtainingexcellent ODS nickel-based superalloy.The purpose of electroless nickel plating on nano Y₂O₃powders was to improve thedispersion in the substrate. The experimental results indicated that the uniform nickelcoated layer was obtained on the surface of Y₂O₃powders when the pH was11, theconcentration of NiSO4was0.2mol/L, the dosage of N2H4H2O was10ml.Milling process, molding process and sintering process were discussed. With350rpmmilling speed can effectively refine grain. Rotating milling can make powder particle sizedistribution and improve the mechanical properties of the alloy. The compacting with highrelative density and bright surface was obtained when the pressing pressure was550MPa,the pressing time was2min. The mechanical property of the alloy was the best when thesintering temperature was1285℃, the content of Ni/Y₂O₃was5wt%. Its microhardnesswas406.3HV, tensile strength was754.8MPa. Electroless nickel plating on surface of theY₂O₃particles was able to effectively improve the mechanical properties of the alloy, thetensile strength of the alloy increased from533.4MPa to754.8MPa.The hot corrosion experiment of the alloy with5wt%Ni/Y₂O₃was explored. Theresults showed that the uniform dispersion of Y₂O₃was able to effectively improve theadhesion of the oxide film. At the same time, it also can provide the priority nucleationposition for Cr₂O₃, promote the formation of the continuous protective layer with Cr₂O₃.The continuous protective layer with Cr₂O₃effectively prevented the spread of the sulfurto the inner layer, slowed down the process of oxide alkaline solution, prolonged theincubation period of hot corrosion process, boosted the performance of resistance hotcorrosion of the alloy.