Limited tensile ductility usually restricts the practical applications of new classes of high-strength materials in many industrial fields. Therefore, in-depth understanding of the work hardening behavior and its underlying plastic deformation mechanism are critical for the newly developed high-entropy alloys (HEAs). In this work, a geometric atomistic model of face-centered cubic (FCC)/ordered body-centered cubic (BCC (B2)) interfaces and the evolution of dislocation substructures have been investigated to explore the microstructural origins of work hardening responses for two additively manufactured AlCoCrFeNi eutectic high-entropy alloys (EHEAs) with the respective lamellar and cellular microstructures. Unlike the lamellar interphase interfaces with the most classical Kurdjumov-Sachs (KS) FCC-BCC relationship of , the Nishiyama-Wassermann (NW) relationship, namely , is observed to be dominant on the cellular interphase interfaces. Furthermore, our intermittent high-resolution transmission electron microscopy (HR-TEM) results directly show that the deformation of lamellar AlCoCrFeNi alloy first proceeds with massive stacking faults (SFs) and then dislocation walls developed across phases interfaces, due to the effective dislocation transfer capability of lamellar boundaries. The large uniform elongation of the cellular AlCoCrFeNi alloy is attributed to the stable and progressive strain-hardening mechanism that is stemmed from the activated multiple slip systems, deformation-induced SF networks, and the associated Lomer-Cottrell locks in the middle and later stages of plastic deformation. Moreover, the nano-bridging of FCC cells in the 3D-printed microstructure provides unique channels for dislocation movement, which offsets the “blocking effect” of cellular boundaries and thus suppresses the pre-mature fracture.

中文翻译：

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激光粉末床熔融 3D 打印 AlCoCrFeNi2.1 共晶高熵合金增强加工硬化和延展性的微观结构起源


有限的拉伸延展性通常限制了新型高强度材料在许多工业领域的实际应用。因此，深入了解加工硬化行为及其潜在的塑性变形机制对于新开发的高熵合金（HEA）至关重要。在这项工作中，研究了面心立方（FCC）/有序体心立方（BCC（B2））界面的几何原子模型和位错子结构的演化，以探索两种增材制造加工硬化响应的微观结构起源。制造了具有各自层状和蜂窝状微观结构的 AlCoCrFeNi 共晶高熵合金（EHEA）。与具有最经典的 Kurdjumov-Sachs (KS) FCC-BCC 关系 的层状界面界面不同，Nishiyama-Wassermann (NW) 关系（即 ）在细胞界面界面上占主导地位。此外，我们的间歇高分辨率透射电子显微镜（HR-TEM）结果直接表明，由于有效的位错转移能力，层状 AlCoCrFeNi 合金的变形首先发生大量堆垛层错（SF），然后在相界面上形成位错壁。的层状边界。多孔 AlCoCrFeNi 合金的大均匀伸长率归因于稳定且渐进的应变硬化机制，该机制源于激活的多重滑移系统、变形诱导的 SF 网络以及中后期相关的 Lomer-Cottrell 锁。塑性变形。 此外，3D打印微结构中FCC细胞的纳米桥接为位错运动提供了独特的通道，抵消了细胞边界的“阻塞效应”，从而抑制了过早断裂。