镍基高温合金铸件中的双氧化膜缺陷分析

Analysis of Double Oxide Film Defects in Ni-Based Super-Alloy Castings

铸件中的双氧化膜缺陷是典型的二维缺陷,面积在平方毫米级而厚度却是微米级,它不在X射线测量范围内,也不在超声波检测范围内,常规方法不易检测到这些缺陷。本研究中通过对镍基高温合金试棒断口扫描电镜观察,应用能谱、波谱仪测量观察点的化学元素,判定该区域是否为氧化物。扫描电镜观察结果揭示了膜状氧化物的存在。本研究证明了在一定的真空铸造条件下镍基高温合金铸件中存在氧化膜,为该缺陷的进一步研究提供了参考,也为如何消除该缺陷指出了方向。

Double oxide film defect in the casting is a typical two-dimensional defect, of which area is in square millimeter level and the thickness is in micron level. It is not in the X-ray flaw detection range, nor in the ultrasonic testing range, the conventional test method is not easy to detect these defects. In this study a number of Ni-based vacuum cast test bars were investigated. The fractures of test bars were observed by scanning electron microscopy （SEM）, energy dispersive spectroscopy （EDS）, as well as wavelength dispersive spectroscopy （WDS） were used to characterize the chemical elements of the fractures＇ surface. Observation by SEM revealed the presence of inclusions identified as films. This study has added to the evidence that oxide film defects do exist in Ni-based super-alloy in certain vacuum casting conditions. It provides a reference for researchers＇ further study on the defects, and provides a possible direction for researchers to remove these defects.