镍基单晶高温合金孔洞区域蠕变行为原位SEM研究  

In⁃situ SEM study on creep behavior in hole region of nickel⁃based single crystal superalloy

作　　者：何文玲 吕俊霞[1] 程晓鹏 王晋 张跃飞 张泽[2] HE Wen-ling;LÜJun-xia;CHENG Xiao-peng;WANG Jin;ZHANG Yue-fei;ZHANG Ze(Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124;School of Materials Science and Engineering,Zhejiang University,Hangzhou Zhejiang 310027,China)

机构地区：[1]北京工业大学材料与制造学部,北京100124 [2]浙江大学材料科学与工程学院,浙江杭州310027

出　　处：《电子显微学报》2022年第5期507-514,共8页Journal of Chinese Electron Microscopy Society

基　　金：国家科技重大专项(No.J2019-Ш-0008-0051);国家自然科学基金基础科学中心项目(No.51988101);北京市自然科学基金重点项目(No.KZ202110005006).

摘　　要：本文采用扫描电镜(SEM)原位高温蠕变实验研究方法,在780℃/720 MPa的蠕变条件下,对镍基单晶高温合金开展蠕变实验,实时观察了孔洞区域显微组织原位演化过程。实验结果表明:蠕变开始后孔洞处应力集中,变形集中于孔洞区域,孔洞旁产生45°及135°方向以及垂直于应力轴的裂纹,多个孔洞共同作用可引起颈缩。颈缩发生后真实应力增加,促进颈缩区孔洞处裂纹垂直于应力轴扩展,而非颈缩区裂纹在切应力作用下沿45°以及135°方向发生扩展。此外蠕变第一阶段已经发生颈缩,导致第二以及第三阶段时间较短,缩短蠕变寿命。揭示了高温下孔洞缺陷对蠕变行为的影响规律及机制,对蠕变寿命预测及高温合金研发有一定启发意义。Scanning electron microscopy(SEM)was used to investigate the in⁃situ creep behavior of nickel⁃based single crystal superalloy at 780℃/720 MPa.Microstructural evolution in hole areas was observed in real time.The experimental result show that the stress concentration leads to the deformation concentrated in the hole areas,and the cracks along 45°and 135°directions and perpendicular to the stress axis are generated.The joint action of multiple holes leads to the necking.After the necking,the real stress in the necking zone increases,which promotes the crack propagation perpendicular to the stress axis,while the crack propagation along the direction of 45°and 135°in the non⁃necking zone under the shear stress.In addition,necking has emerged in the first stage of creep,resulting in the shorter time in the second and third stages of the creep life.This work reveals the effect of hole defectson creep behavior at high temperature,which is instructive for the prediction of creep life and the development of superalloy.

关 键 词：镍基单晶高温合金 原位蠕变 颈缩 孔洞 裂纹 

分 类 号：TG132.3[一般工业技术—材料科学与工程] TG146.15[金属学及工艺—合金] TG115.215.3[金属学及工艺—金属学]