Dislocation array reflection enhances strain hardening of a dual-phase heterostructured high-entropy alloy

Piling-ups of geometrically necessary dislocation (GND) arrays against interfaces are known to produce hetero-deformation induced (HDI) strengthening and strain hardening to enhance the strength and ductility of heterostructured materials. Here we report an interesting dislocation mechanism that can produce strong HDI hardening: consecutive reflections of GND planar piling-up arrays near the opposite phase boundaries in a heterostructured AlCoCrFeNi₂ high entropy alloy (HEA). In contrast, dislocation transmission was found at grain boundaries in the fcc phase. The discovery here provides guidance for future materials design, which may improve the combination of strength and ductility of metallic materials. A hitherto unknown consecutive reflection of GND arrays near phase boundaries of a heterostructured HEA is observed and proposed as a key contributor to HDI hardening.

几何必需位错（geometrically necessary dislocation, GND）阵列在界面处的塞积，已被证实可产生异质变形诱导（hetero-deformation induced, HDI）强化与应变硬化，从而提升异质结构材料的强度与延性。本研究报道了一种可实现显著异质变形诱导硬化的新奇位错机制：在异质结构AlCoCrFeNi₂高熵合金（high entropy alloy, HEA）的异相界面附近，几何必需位错平面塞积阵列发生连续反射。与之相反，在面心立方（FCC）相的晶界处观测到了位错穿越现象。本研究的发现可为未来材料设计提供指导，有望优化金属材料的强度与延性综合性能。本研究观测到异质结构高熵合金相界附近此前未见报道的几何必需位错阵列连续反射现象，并提出该现象是异质变形诱导硬化的关键贡献因素。