镍基单晶高温合金中小角晶界失效机制的原位研究

王文帅，李雪峤，龙海波*，毛圣成, 张  泽，韩晓东

（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）

摘  要  现阶段制备出的镍基单晶高温合金中常常难以避免平行于加载方向的小角晶界存在，开展小角晶界失效机制的研究对于综合评价镍基单晶合金的服役性能具有重要指导作用。本文通过双籽晶法制备出含有小角晶界的双晶高温合金，采用透射电镜中的原位技术，开展小角晶界对镍基单晶高温合金失效机制的研究。研究发现，改变籽晶的排布方式可以制备出晶界近似平行(010)和(1"1"  ̅0)晶面的两类双晶；当沿(010)晶面的晶界进行拉伸时，两侧晶粒分别发生了沿滑移面的解理断裂及横截面的脆性断裂；而沿(1"1"  ̅0)晶面的晶界进行拉伸时，两侧晶粒仅发生沿滑移面的解理断裂。上述现象主要由合金内取向因子的差异所导致。

关键词  镍基单晶高温合金；小角晶界；失效机制；原位研究

中图分类号：TG132.3+2；TG115.21+5.3；TB31  文献标识码：A        doi:10.3969/j.issn.1000-6281.2022.06.002

In-situ study on failure mechanism of Ni-base single crystal superalloy with small angle grain boundary

WANG Wen-shuai¹, LI Xue-qiao¹, LONG Hai-bo¹*, MAO Sheng-cheng¹, ZHANG Ze^1，2, HAN Xiao-dong¹

(1. Faculty of Materials and Manufacturing, Beijing University of Technology,  Beijing 100124；2. School of Materials Science and Engineering, Zhejiang University, Hangzhou Zhangjiang 310008, China)

Abstract  It is difficult to avoid the existence of small-angle grain boundaries parallel to the loading direction in the preparation of Ni-base single crystal super alloys at the present stage. The study of the failure mechanism of small-angle grain boundaries plays an important role in the comprehensive evaluation of the service properties of Ni-base single crystal alloys.In this paper, bicrystals superalloy with small angle grain boundary was prepared by double seed method, and the failure mechanism of nickel base single crystal superalloy with small angle grain boundary was studied by in-situ technology in transmission electron microscope.It is found that by changing the arrangement of seed grains, two kinds of bicrystals with grain boundaries approximately parallel to (010) and (10) planes can be prepared; when the grain boundaries are stretched along the(010) plane, the dissociation fracture along the slip plane and the brittle fracture along the cross section occur respectively, while when the grain boundary is stretched along the (10) plane, the dissociation fracture of the grains on both sides only occurs along the slip plane.The above phenomenon is mainly caused by the difference of orientation factors in the alloy.

Keywords Ni-based single crystal superalloys; small angle grain boundary; failure mechanism; in-situ

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