Abstract We investigate the microstructure and deformation substructure evolution in an additively manufactured 1.8 at.% N-doped FeCoNiCr high-entropy alloy (HEA) by means of correlative electron backscatter diffraction (EBSD) and electron channeling contrast imaging (ECCI). The combinational use of EBSD and ECCI uncovers hierarchal structures of the HEA at multiple length scales, which consist of a bimodal grain structure, low angle boundaries, and dislocation networks, along with the quantitative evolution of geometrically necessary dislocations (GNDs) distribution. The ECCI technique shows comparable resolution to transmission electron microscopy (TEM) in terms of characterizing the dislocation substructures. We further clarify the strain hardening mechanisms by investigating the deformation microstructures. The excellent strain hardening rate of the HEA even at large strain is due to the jointly activation of slip bands and mechanical twining. The deformation induced twining shows strong orientation dependence.

中文翻译：

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通过相关 EBSD 和 ECCI 表征分级高熵合金的微观结构和变形亚结构演变

摘要 我们通过相关电子背散射衍射 (EBSD) 和电子通道对比成像 (ECCI) 研究了增材制造的 1.8 at.% N 掺杂 FeCoNiCr 高熵合金 (HEA) 的微观结构和变形亚结构演变。EBSD 和 ECCI 的组合使用揭示了 HEA 在多个长度尺度上的分层结构，其中包括双峰晶粒结构、低角度边界和位错网络，以及几何必要位错 (GND) 分布的定量演变。ECCI 技术在表征位错亚结构方面显示出与透射电子显微镜 (TEM) 相当的分辨率。我们通过研究变形微观结构进一步阐明了应变硬化机制。即使在大应变下，HEA 的优异应变硬化率也是由于滑带和机械缠绕的共同激活。变形诱导的缠绕显示出强烈的取向依赖性。