高温合金GH4169疲劳裂纹尖端组织观察

本文通过透射电镜观察分析了高温合金GH4169疲劳裂纹尖端的组织，比较了裂纹附近组织与基体组织的异同，对深入探索GH4169合金裂纹形成机制具有重要意义。研究结果表明：GH4169合金裂纹两侧及裂纹前端存在大量挛晶，挛晶主要分布在距裂纹表面10-20um深度范围内；对这种高温合金而言，高应变速率下，孪生是主要变形机制之一；用高分辨电镜观察裂纹截面试样，发现挛晶层与裂纹表面之间还有一层多晶组织，主要由GH4169合金中的面心立方结构Y相组成，多晶层厚度约200—500nm。

Microstructure of Fatigue Crack Tip in GH4169 Superalloy

The microstructure of fatigue crack tip in GH4169 superalloy was observed and analyzed by transmission electron microscopy, and which was also compared with the matrix structure. Research results showed that there are a great deal of twin crystals ila the two sides of the fracture and crack front. They are distributed mainly in the area with depth of 10-20μm.For the GH4169 supperalloy, twinning is the main deformation mechanism during deformation with high strain rate. The study by high resolution electron microscopy （HREM） pointed out that a polycrystalline layer exists between the twin layer and the crack surface,its thickness is about 200-500nm.In the GH4169 supperalloy, this polycrystalline layer mainly consists of γ phase with face centered cubic structure