Transmission electron microscopy characterization of dislocation structure in a face-centered cubic high-entropy alloy Al0.1CoCrFeNi
Transmission electron microscopy characterization of dislocation structure in a face-centered cubic high-entropy alloy Al0.1CoCrFeNi
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DOI：
10.1016/j.actamat.2017.10.050
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发表时间：
2018-02
期刊：
影响因子：
9.4
通讯作者：
Xiandong Xu;Pan Liu;Z. Tang;A. Hirata;Shaoli Song;T. Nieh;P. Liaw;C. Liu;Mingwei Chen
中科院分区：
文献类型：
--
作者：
Xiandong Xu;Pan Liu;Z. Tang;A. Hirata;Shaoli Song;T. Nieh;P. Liaw;C. Liu;Mingwei Chen
采用最先进的球面像差校正透射电子显微镜对面心立方高熵合金的位错和位错反应进行了结构表征。利用位错核的原子图像和衍射对比实验测量了高熵合金的层错能。低的层错能导致广泛的位错解离和广泛的位错反应，从而形成不动的Lomer和lomo - cottrell位错锁。这些位错锁既是位错屏障又是位错源，是导致合金加工硬化的主要原因。基于原子尺度表征和经典位错理论，推导了高熵合金塑性变形初期加工硬化行为的简单方程。
Structural characterization of dislocations and dislocation reactions in a face-centered cubic high entropy alloy was conducted using the state-of-the-art spherical aberration corrected transmission electron microscopy. We experimentally measured the stacking fault energy of the high entropy alloy from the atomic images and diffraction contrast of dislocation cores. The low stacking fault energy results in widely dissociated dislocations and extensive dislocation reactions, which leads to the formation of immobile Lomer and Lomer-Cottrell dislocation locks. These dislocation locks act as both dislocation barriers and sources and are responsible for the significant work hardening with a large hardening rate in the alloy. Based on the atomic-scale characterization and classical dislocation theory, a simple equation was derived to describe the work hardening behavior of the high entropy alloy in the early-stage of plastic deformation.