镍基单晶高温合金DD10的恒温氧化行为

采用X射线衍射(XRD)，扫描电镜(SEM)及能谱(EDX)等方法研究了不同钴含量的两种镍基单晶高温合金在900，1000和1100 ℃的恒温氧化行为。研究发现，增加合金中的Co含量，会降低合金的扩散激活能，引起氧化速率的略微增加。在900和1000 ℃氧化时符合抛物线规律，氧化膜分为3层：外层主要由Cr2O3和TiO2组成；中间层是很薄的CrTaO4和Ta2O5氧化层；内层是连续的Al2O3氧化层。在1100 ℃时氧化膜的严重剥落和CrO3的挥发使增重曲线略微偏离抛物线规律，生成了NiCr2O4, CoAl2O4, CoNiO2和Co2TiO4等尖晶石相，并发生了内氮化

Isothermal Oxidation Behavior of Single-Crystal Nickel-Base Superalloy DD10

The isothermal oxidation behaviors of two kinds of single-crystal nickel-base superalloys DD10 with different cobalt contents were investigated at 900, 1000 and 1100 oC in air by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy disperse X-ray analysis (EDX). It is found that increasing the cobalt content can decrease the diffusion activity energy of the alloy and thus increase the oxidation rate slightly. For the oxidation at 900 oC and 1000 oC, the mass gain basically obeys the parabola law. The oxide scales consist of three layers: an outer layer of Cr2O3 and TiO2, a thin intermediate layer of CrTaO4 and Ta2O5, and a continuous inner layer of Al2O3. For the oxidation at 1100 oC, because of the severe spalling of the scale and the volatilization of the CrO3, the kinetics curves deviate from the parabolic law a little. Some spinels such as NiCr2O4, CoAl2O4, CoNiO2 and Co2TiO4 form and inner nitridation phenomenon happens