Compositionally-complex alloys (CCAs) with the face-centered cubic (fcc) structure exhibit excellent fracture toughness and stable mechanical property across a broad temperature range from cryogenic to room temperatures. However, yield strength of those alloys is usually low, making them difficult to meet the demands of practical engineering application. In a prototype CCA with the nominal chemical composition of Co₁₀Cr₁₀Fe₄₉Mn₃₀N₁ (atom percent), a multi-scaled heterostructure from sample to atomic scales was obtained by performing triaxial cyclic compression and short-term annealing on the blocky alloy. The material exhibits a heterogeneous distribution of strain at the sample scale. At the grain scale, dense twins and twin–twin network, laths featured with local chemical order as well as dislocation cells jointly hinder plastic deformation. At the nanoscale, the chemical order within grains also impedes dislocation motion. During plastic deformation, different sample positions within the heterogeneous material and various regions at each position undergo coordinated deformation, resulting in significant hetero-deformation induced strengthening. Simultaneously, the continuously activated dislocations, stacking faults and nano-twins lead to a high yield strength of 1020 MPa in the material while maintaining a fracture elongation of 30%. This study provides new insights for the design and development of high-performance metallic materials.

中文翻译：

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多尺度异质结构可实现 CoCrFeMnN 成分复杂合金的卓越强度-延展性组合


具有面心立方 （fcc） 结构的复合成分合金 （CCA） 在从低温到室温的宽温度范围内表现出优异的断裂韧性和稳定的机械性能。然而，这些合金的屈服强度通常很低，这使得它们难以满足实际工程应用的需求。在标称化学成分为 Co₁₀Cr₁₀Fe₄₉Mn₃₀N₁ （原子百分比） 的原型 CCA 中，通过对块状合金进行三轴循环压缩和短期退火，获得了从样品到原子尺度的多尺度异质结构。该材料在样品尺度上表现出应变的异质分布。在晶粒尺度上，致密孪晶和孪晶网络、具有局部化学有序特性的板条以及位错胞共同阻碍了塑性变形。在纳米尺度上，晶粒内的化学有序也阻碍了位错运动。在塑性变形过程中，异质材料内的不同样品位置和每个位置的不同区域发生协调变形，导致显著的异质变形诱导强化。同时，连续激活的位错、堆叠缺陷和纳米孪晶导致材料具有 1020 MPa 的高屈服强度，同时保持了 30% 的断裂伸长率。本研究为高性能金属材料的设计和开发提供了新的见解。