电子束物理气相沉积制备NiCrCoAl合金在1000℃的氧化行为

Oxidation Behaviors of NiCrCoAl Superalloy Sheet Prepared by EB-PVD at 1000℃

对物理气相沉积制备的微晶材料Ni-11.5Cr-4.5Co-0.5Al高温合金薄板在1 000℃空气中恒温氧化进行了研究,用扫描电镜对氧化试样的表面和截面形貌进行观察,用X射线衍射仪与能谱仪对其相和成分分布进行了分析。结果表明:微晶材料高温合金板在初始氧化阶段遵循抛物线规律,长时间氧化时遵循四次方规律;氧化时表面形成细小、致密的氧化物层,随着时间的延长氧化物颗粒逐渐长大,外表面形成NiO、CoCr_2O_4和Cr_2O_3混合氧化物;氧化96h的截面有一连续Al_2O_3层在氧化物和基体界面形成。

The isothermal oxidation behavior of microcrystalline Ni-11. 5Cr-4. 5Co-0. 5Al superalloy sheet fabricated by Electron Beam Physical Vapor Deposition （EB-PVD） at 1 000 ℃ in air was investigated in this paper. The oxidation kinetics of microcrystalline superalloy sheet followed a parabolic power law at initial stage of oxidation, and four power law for long oxidation terms. Surfaces and cross-sections of the oxidized specimens were studied by scanning electron microscopy （SEM）. Phase identification of the oxide scale was performed by Small Angle X-ray diffraction （SAXD） and Energy Dispersive Analysis of X-rays （EDAX）. The fine and compact oxide formed on the microcrystalline superalloy surface grows up with time. The oxide scales consisted mainly of an outer NiO, CoCr2O4 and Cr2O3 mixed oxides. And a continuous inner oxide layer of Al2O3 formed can be observed at 96 h oxidation.