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通过对有无NiCrAlY涂层镍基单晶合金进行不同温度的恒温氧化动力学曲线测定及组织结构观察,研究了纳米晶NiCrAlY涂层对高Cr单晶镍基合金高温氧化行为的影响。结果表明:在高温氧化期间,无涂层试样发生明显的氧化、内氧化和内氮化,在表层为Al2O3、Cr2O3的混合氧化物,在次表层氧化物中富含元素Ta,而元素Al贫化,并在近基体区域存在内氧化物;随氧化温度升高,元素Al的贫化区尺寸增大,其中,富Ta相可抑制基体中元素Al向外扩散,延缓合金的氧化速率。合金在氧化初期增重迅速,而恒温氧化增重动力学曲线呈现起伏波动的原因,归结于表面氧化膜的形成与剥落。高Cr单晶合金经溅射NiCrAlY纳米晶涂层,可有效改善合金的抗氧化性能;有涂层试样在不同温度的恒温氧化动力学曲线仅在氧化初期有轻微增重而后趋于平稳,其形成的Al2O3氧化膜不发生明显的剥落,仅在基体近涂层/基体界面区域存在少量AlN内氮化物。
The effect of nanocrystalline NiCrAlY coating on the oxidation behavior of high Cr single crystal nickel-base alloy at high temperature was studied by measuring the isothermal oxidation kinetics curve and microstructure of NiCrAlY-coated Ni-based single crystal alloy at different temperatures. The results show that during the high temperature oxidation, the uncoated samples have obvious oxidation, internal oxidation and internal nitriding. In the surface layer, there are mixed oxides of Al2O3 and Cr2O3, while the sub-surface oxide is rich in elemental Ta. The elemental Al Depleted, and there is an internal oxide in the near matrix region. As the oxidation temperature increases, the size of the depleted zone of elemental Al increases, and the Ta-rich phase can inhibit the outward diffusion of elemental Al in the matrix and delay the oxidation rate of the alloy. During the initial oxidation stage, the weight gain of the alloy rapidly increases, while the kinetic curve of oxidation and weight gain at constant temperature shows fluctuation and fluctuation, which is attributed to the formation and exfoliation of the surface oxide film. High-Cr single crystal alloy by sputtering NiCrAlY nanocrystalline coating, which can effectively improve the oxidation resistance of the alloy; coated samples at different temperatures constant temperature oxidation kinetics curve only slight oxidation in the initial weight gain and then tend to be stable, The formed Al 2 O 3 oxide film does not peel off obviously, and only a small amount of AlN inner nitride exists in the near-substrate / substrate interface region.