Body-centered-cubic (BCC) high-entropy alloys (HEAs) encounter significant challenges in obtaining a high uniform tensile ductility (UTD). A dense dislocation-cell (DC) structure is produced in a heterogeneously grained HEA under tensile deformation, resulting from the anchored dislocation motion by grain interior elemental segregation. This fluctuation in elemental concentration is facilitated by thermomechanical processing. The activation of multiple-slip mechanisms, prompted by strain incompatibility among grains of varying sizes, significantly propels this process forward. This novel DC structure simultaneously increased the UTD (by 349.1 %) and yield strength (, by 29.0 %) for a stable BCC HEA. Specifically, the single-phase alloy achieved a record-high UTD of 7.5 % and an of > 1,200 MPa, outperforming the counterparts of all the single-phase BCC HEAs. We employed a combination of transmission electron microscopy, in-situ scanning electron microscopy tensile testing coupled with an electron backscatter diffraction technology to investigate underlying strengthening mechanisms and identified that the serious stress concentration as a result of prevalent planar slip caused premature failure and localized strain of common BCC HEAs. At the initial stage of deformation, the DC structure promoted the activation of multiple slip systems and facilitated the extension of a plastic flow across the sample volume, effectively weakening stress concentration and premature failure. The extended plasticity zone and intensified dislocation interactions contributed to the increased UTD and . These findings offer valuable inspiration for tailoring alloy properties via microstructure strategies and promoting their adoption in advanced manufacturing.

中文翻译：

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在位错胞结构高熵合金中实现优异的均匀拉伸延展性和强度


体心立方 (BCC) 高熵合金 (HEA) 在获得高均匀拉伸延展性 (UTD) 方面遇到重大挑战。在拉伸变形下，异质晶粒 HEA 中产生致密位错单元 (DC) 结构，这是由晶粒内部元素偏析产生的锚定位错运动造成的。热机械加工促进了元素浓度​​的波动。由不同尺寸颗粒之间的应变不相容性引起的多重滑移机制的激活，显着推动了这一过程的发展。这种新颖的 DC 结构同时提高了稳定 BCC HEA 的 UTD（增加 349.1%）和屈服强度（增加 29.0%）。具体而言，该单相合金实现了 7.5% 的历史最高 UTD 和 > 1,200 MPa，优于所有单相 BCC HEA 的同类产品。我们采用透射电子显微镜、原位扫描电子显微镜拉伸测试与电子背散射衍射技术相结合来研究潜在的强化机制，并发现普遍的平面滑移导致的严重应力集中导致过早失效和局部应变。常见的 BCC HEA。在变形初始阶段，DC结构促进了多个滑移系统的激活，并有利于塑性流在整个样品体积中的扩展，有效削弱了应力集中和过早失效。塑性区的扩展和位错相互作用的增强导致了 UTD 和 的增加。这些发现为通过微观结构策略定制合金性能并促进其在先进制造中的采用提供了宝贵的启发。