孔几何结构对DD6单晶高温合金氧化行为影响

Effect of Hole Geometric Structure on the Oxidation Behavior of DD6 Single-Crystal Superalloy

摘要:

利用场发射扫描电子显微镜（FESEM）、能谱仪（EDS）、X射线衍射（XRD）以及ABAQUS有限元等方法，研究了孔几何结构对DD6单晶高温合金在1050 ℃氧化行为的影响。结果表明：在45°和90°两种角度下，平均氧化速率随着气膜孔间距的变化规律较一致，均为0.75>0.95>0.55>0.39 mm，气膜孔间距对单晶合金氧化行为的影响比孔角度的影响更为显著；在相同气膜孔间距下，45°比90°的氧化程度相对严重一些。有限元分析表明，孔内壁氧化层生长主要受温度场影响，而孔表面氧化层生长主要受氧化膜脱落应力的影响；随着气膜孔间距增大，应力抵消区域逐渐减小，脱落应力不断增大，并在0.75 mm时达到峰值，此时氧化膜脱落最为严重，峰值点之后又呈下降趋势。

Abstract:

The isothermal oxidation behavior of DD6 single-crystal superalloy with different hole geometric structure at 1050 ℃ was studied using field emission scanning electron microscope, energy dispersive spectroscope, X-ray diffractometer, and ABAQUS finite element method. The results show that at two angles of 45° and 90°, the average oxidation rate varies with the film-hole spacing, both being 0.75 mm>0.95 mm>0.55 mm>0.39 mm. The effect of film-hole spacing on the oxidation mass gain of single-crystal superalloys is more significant than that of hole angle. At the same film-hole spacing, the degree of oxidation at 45° is relatively more severe than that at 90°. Finite element analysis shows that the growth of the oxide layer on the inner wall of the hole is mainly affected by the temperature field, while the growth of the oxide layer on the surface of the hole is mainly affected by the detachment stress. As the film-hole spacing increases, the stress cancellation area gradually decreases, and the detachment stress continues to increase, reaching its peak at 0.75 mm. At this time, the oxide film detachment is most severe, and after the peak point, it shows a downward trend.