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本文对一种单晶高温合金在800℃经高周疲劳实验的断裂特征和微观变形机制进行了详细研究,发现该单晶合金存在两种断裂形貌,一种是定向解理断裂,一种是蜂窝状撕裂,这两种断裂方式分别与按确定取向的滑移变形机制和位错胞变形机制相联系。还观察到了小角晶界的变形机制,合金中存在的极微量 MC 碳化物仍然是重要的疲劳源,该单晶高温合金的高周疲劳强度极限较之相应的普通铸造 IN738合金和低偏析定向凝固 DE38G 合金大幅度提高。
In this paper, the fracture characteristics and microscopic deformation mechanism of a single crystal superalloy subjected to high cycle fatigue test at 800 ℃ have been studied in detail. It is found that the single crystal superalloy has two kinds of fracture morphology, one is directional cleavage fracture, Is honeycomb-shaped tearing, and the two fracture modes are related to the slipping deformation mechanism and the dislocation cell deformation mechanism according to a certain orientation, respectively. Also observed in the small angle grain boundary deformation mechanism, the existence of a trace amount of MC carbide carbide is still an important source of fatigue, the single-crystal superalloy high-cycle fatigue strength limit compared with the corresponding ordinary cast IN738 alloy and low segregation directional solidification DE38G alloy increased significantly.