压应力下Ni-10Cr合金高温氧化膜裂纹的愈合行为

Oxide-scale crack healing behavior of Ni-10Cr alloy in presence of external compressive stress

为提高合金的使用寿命,针对载荷作用影响高温氧化膜行为的问题,通过扫描电子显微镜观察氧化膜的表面形貌,对比研究Ni-10Cr合金在900℃有无压应力作用下氧化膜的愈合行为。结果表明:在压应力下氧化48 h后,氧化膜产生了楔形裂纹,并开始伴有氧化膜裂纹愈合的现象;氧化至72 h时,随着应力的增加,氧化膜裂纹处形貌发生改变,5 MPa时生成的脊状氧化物对氧化膜裂纹具有更优的愈合作用。这种氧化膜裂纹愈合对氧化膜的保护作用尤其重要。

This paper seeks to improve the service life of alloys and addresses the effect of the external loading on the high temperature oxide-scale behavior.The study involves investigating the effect of a compressive stress on the oxide-scale morphology by comparing the oxidation behavior of Ni-10Cr alloy in air at 900 ℃.It was performed mainly by comparison of surface morphology observed by scanning electronic microscopy（SEM）.The results show that the oxide scales experience wedge-type cracks after 48 h of oxidation when the specimens are subjected to a stress;after 72 h, the morphologies near the oxide-scale cracks change with the increasing external stress;and the formation of ridge-like oxide bond under 5 MPa stress is more likely to heal the oxide-scale cracks.It follows that the oxide-scale crack healing process proves very important for the oxide-scale protective behavior.