Re segregation at interfacial dislocation network in a nickel-based superalloy
Re segregation at interfacial dislocation network in a nickel-based superalloy
复制标题
镍基高温合金界面位错网络的再偏析
DOI：
10.1016/j.actamat.2018.05.025
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发表时间：
2018-08-01
期刊：
影响因子：
9.4
通讯作者：
Li, Jixue
中科院分区：
文献类型：
--
作者：
Ding, Qingqing;Li, Suzhi;Li, Jixue
用亚埃分辨透射电子显微镜和能谱仪研究了Re在镍基单晶高温合金中的分布。结果表明，Re原子在界面位错核附近的拉应力区偏聚，形成了“Cottrell气氛”，位错管扩散促进了Re的偏析过程。原位电子显微镜和扫描电子显微镜应变研究表明，沿相界重新修饰的位错网络起到了机械壁的作用，有效地阻止了位错的运动和裂纹的扩展。此外，再偏析的程度可以通过热处理来调节。理论分析表明，这种显著的合金化效应主要源于Re的局部成分应变与位错应变之间的相互作用，导致界面位错网络显著稳定。这些结果为理解Re对镍基高温合金力学性能影响的原因提供了新的视角，并将有助于改善镍基高温合金的蠕变性能和设计高性能的无Re高温合金。(C)2018 Acta Materialia Inc.由Elsevier Ltd.出版。保留所有权利。
The distribution of Rhenium (Re) in a Ni-based single-crystal superalloy is studied by sub-angstrom resolution transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). It is found that Re atoms segregate at the tensile stress regions near the interfacial dislocation cores, forming the "Cottrell atmosphere", and the segregation process is facilitated by dislocation pipe diffusion. In situ TEM and scanning electron microscopy (SEM) straining studies reveal that the Re-decorated dislocation networks along the phase boundaries act as mechanical walls that effectively block dislocation motion and crack propagation. Furthermore, the degree of Re segregation can be regulated by thermal treatment. Theoretical analysis demonstrates that this remarkable alloying effect originated mainly from the interactions between the local composition strain of Re and the dislocation strains, leading to significantly stabilized interfacial dislocation networks. These results provide a new perspective on understanding the origin of the Re effect on mechanical properties in Ni-based super alloys and will be beneficial to both improving creep properties of Ni-based superalloys and designing high-performance Re-free superalloys. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.