Preparation And High Temperature Oxidation Resistance Of Pulse Electron Beam Cr Alloyed/Aluminized Coating On Gh3039 Superalloy

GH3039 nickel base superalloy is a typical single-phase austenitic alloy.It has better oxidation resistance when the temperature environment is not higher than 1000?.Therefore,the material can be used as combustion chamber components in aircraft engines,and its service temperature is generally not higher than 850?.In this paper,the surface of GH3039 alloy was Cr Alloyed by"hope-I"high current pulse electron beam?HCPEB?device.The irradiation times were 10,20 and 30;A layer of aluminizing coating was prepared on the surface of gh3039 nickel base superalloy by powder embedding aluminizing process.The changes of the microstructure of the sample surface and the aluminized coating were analyzed by XRD and SEM.The static oxidation discontinuous weighing method was used to test the high temperature oxidation resistance of the sample after surface modification.Scanning electron microscope?SEM?and energy dispersive spectrometer?EDS?were used to characterize the morphology and composition of the surface oxidation products of the original samples and the treated samples after 100 h oxidation.The mechanism of the change of the surface properties of the samples was discussed based on the results of microscopic characterization.The specific research results are as follows:?1?The XRD pattern of Cr alloying by HCPEB irradiation surface shows that the position of the corresponding diffraction peak does not change significantly before and after the irradiation alloying.The XRD diffraction peak of the irradiated sample does not produce the diffraction peak of Cr,and no new phase appears,which should be caused by Cr dissolving into the matrix during HCPEB irradiation.The surface layer of the samples before and after aluminizing contains matrix?/?'phase,while the surface of the samples after aluminizing is mainly composed of Ni₂A1₃ phase,with a small amount of NiAl₃ phase and Cr precipitation phase Al₈₆Cr₁₄.?2?The surface of Cr alloying treated by HCPEB irradiation produces slip band and ultrafine structure,which can provide a channel for the diffusion of atoms,and the high energy state of the surface also provides an important driving force for the diffusion of atoms.Samples treated by embedding aluminizing,a continuous aluminizing coating was formed on the surface of the substrate,and the thickness of the coating was uniform,about 90?m.The coating is mainly divided into three layers:the outermost layer is mainly al rich Ni₂Al₃ phase and part of NiAl₃ phase;the middle layer is mainly Ni₂Al₃phase;the inner layer is Ni rich?-NiAl phase.?3?The results of high temperature oxidation show that there are three stages in the process of oxidation of the samples before and after HCPEB irradiation Cr alloying at 850?for 100 h:mixed oxidation stage,steady-state oxidation stage and rapid oxidation stage.The increasing importance of irradiation alloying samples is obviously smaller than that of the original samples,and with the increase of irradiation times,the rate of increasing weight shows a downward trend.The weight gain rate of 30irradiation treatments was the lowest,and the corresponding high temperature oxidation resistance was the best.The oxidation kinetics of the samples before and after aluminizing was similar,but the oxidation increment of the aluminized samples was significantly lower than that of the original samples.?4?In the high temperature oxidation experiment of the samples before and after the HCPEB irradiation Cr alloying treatment,the oxide on the surface of the original sample is mainly composed of mixed oxide,the oxide film is not dense enough,and serious TiO₂ internal oxidation occurs inside;the surface of the HCPEB irradiation Cr alloy sample is composed of relatively complete and dense Cr₂O₃ oxide film,and a small amount of TiO₂ is doped inside,and there are pin like Al₂O₃ internal oxide,the binding force between the oxide film and the substrate can be increased under its pinning effect.The oxide film on the surface of aluminized sample is mainly blade like Al₂O₃ at 800?;the oxide film at 900? is composed of massive and blade like Al₂O₃ with relatively large particle size;the oxide film on the surface of aluminized sample at 1000?is mainly block like?-Al₂O₃ with denser oxide film.