The development of high-entropy intermetallic (HEI) with core-shell structure is promising for solving strength-ductility dilemma. Here, we successfully impart stable dual-scale L12-type ordered core into as-cast HEI, promoting a novel L12-type HEI Ni50Co25Cr9.5Al9Ti5Ta1.5 with hierarchical core-shell structure. The locally compositional segregation induced hierarchical core-shell structure contributes to an excellent strength-ductility synergy with yield strength, ultimate tensile strength and uniform elongation of ∼1000 MPa, ∼1250 MPa and ∼12 %, respectively. Our study reveals that the outstanding strength is attributed to significant micro-level precipitation strengthening and additional multi-level hetero-deformation induced (HDI) strengthening. Besides, the considerable ductility is ascribed to active dislocation movement and remarkable strain hardening capability. Moreover, micro-level SFs dominated deformation mechanism and macro-level fracture mechanism are also carefully investigated. The purpose of this work is not only to improve mechanical properties of as-cast L12-type HEI, but more importantly to correlate hierarchical core-shell structure with mechanical properties, deformation behavior and fracture mechanism, so as to shed light on a new direction for exploring novel advanced as-cast structural materials.

中文翻译：

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在具有分层核壳结构的新型铸态 L12 型 HEI Ni50Co25Cr9.5Al9Ti5Ta1.5 中具有优异的强度-延展性协同作用


具有核壳结构的高熵金属间化合物 （HEI） 的开发有望解决强度-延展性困境。在这里，我们成功地将稳定的双尺度 L12 型有序核心赋予铸态 HEI 中，推广了一种具有分层核壳结构的新型 L12 型 HEI Ni50Co25Cr9.5Al9Ti5Ta1.5。局部成分偏析诱导的分层核壳结构有助于实现出色的强度-延展性协同作用，屈服强度、极限拉伸强度和均匀伸长率分别为 ∼1000 MPa、∼1250 MPa 和 ∼12 %。我们的研究表明，突出的强度归因于显著的微观水平降水强化和额外的多级异质变形诱导 （HDI） 强化。此外，相当大的延展性归因于主动位错运动和卓越的应变硬化能力。此外，还仔细研究了微观水平 SFs 主导的变形机制和宏观水平的断裂机制。这项工作的目的不仅是提高铸态 L12 型 HEI 的力学性能，更重要的是将分层核壳结构与力学性能、变形行为和断裂机制相关联，从而为探索新型先进铸态结构材料指明新的方向。