磨削诱导单晶高温合金微观组织演化机制研究  

Study on Mechanism of Microstructure Evolution Induced by Grinding for Single Crystal Superalloy

作　　者：徐运超 李景栋 张智信 庞桂兵[1] 巩亚东[2] XU Yun-chao;LI Jing-dong;ZHANG Zhi-xin;PANG Gui-bing;GONG Ya-dong(School of Mechanical Engineering&Automation,Dalian Polytechnic University,Liaoning Dalian 116034,China;School of Mechanical Engineering&Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]大连工业大学机械工程与自动化学院,辽宁大连116034 [2]东北大学机械工程与自动化学院,沈阳110189

出　　处：《表面技术》2023年第12期83-90,共8页Surface Technology

基　　金：国家自然科学联合基金(U1908230);国家自然科学基金(51975081);辽宁省教育厅基本科研项目(JYTQN2023117)。

摘　　要：目的通过对零件磨削表面的微观组织进行表征,探讨高温和大应变条件下单晶高温合金晶体取向和位错的演化机制。方法采用场发射扫描电子显微镜对磨削亚表面微观组织形貌进行观察,通过X射线衍射技术对磨削前后表面晶体取向进行分析。利用聚焦离子束定向切割技术制备了磨削表面透射电子扫描样品,采用透射电子显微镜和透射菊池衍射方法对表面白层以及塑性变形层晶体取向以及位错分布进行了表征。结果磨削后单晶高温合金表面形成强烈塑性变形,原始单一取向发生改变,形成多晶衍射峰特征。磨削表面深度方向上形成具有不同晶粒尺寸和取向的梯度组织结构。选区衍射花样显示原始单晶材料的衍射斑点转变为多晶材料的衍射环。磨削表面由于强烈剪切变形和磨削热产生微纳尺度的动态再结晶现象,同时形成高密度位错结构。磨削表面产生强烈的剪切应变,使晶体向有利于剪切变形的方向旋转,形成了R-Cube织构和F剪切织构。结论单晶高温合金磨削表面微观组织演化是基于微纳尺度的动态再结晶和位错滑移运动进行的。Due to its excellent creep and fatigue resistance at high temperatures,the microstructure control during the forming and mechanical processing of single crystal superalloy widely used in hot end components of aircraft engines has always been a hot topic of concern.At present,the theory of dislocation slip and recrystallization at high strain rates for this special material without original grain boundaries is currently unclear.Thus,the mechanism of microstructure evolution on the surface of single crystal superalloy parts was obtained through grinding experiments in this work.The sample for transmission electron microscopy(TEM)of ground surface was prepared by focused ion beam(FIB)directed cutting technique.The microstructure,orientation,grain size,and dislocation density distribution on the ground surface were characterized using field emission scanning electron microscopy(FE-SEM),X-ray diffraction technology(XRD),TEM,and transmission Kikuchi diffraction(TKD)technology,respectively.The results indicate that a gradient structure with white layer,plastic deformation layer,and bulk material are formed below the ground surface,and dynamic recrystallization phenomenon is generated on the subsurface.The SEM results show that there is no obvious deformation feature in the white layer,while a large number of slip traces are formed in the plastic deformation layer.The original structure ofγ/γ′phase is destroyed,exhibiting typical shear deformation characteristics.XRD results show that the original single orientation of the single crystal superalloy is transformed into multiple diffraction peaks(111),(200),(220),(311)and(222).TEM detection indicate that dynamic recrystallization occurred in the top surface layer of single crystal parts during grinding,resulting in grain refinement at the nanoscale.The surface of single crystal parts has transformed from a special organizational structure with only a single grain to a polycrystalline structure characterized by the coexistence of nano equiaxed grains and subgrains.A lar

关 键 词：磨削加工 镍基单晶高温合金 动态再结晶 白层 微观组织 

分 类 号：TG356.28[金属学及工艺—金属压力加工]