Shi Peijian, Li Yi, Li Zhi, Jiang Xin, Yan Jie, Zhou Rui, Qin Yi, Lin Yifan, Huang Jingran, Tan Bodong, Wang Yinan, Wen Tongqi, Ye Beilin, Ling Chunyan, Luan Junhua, Shen Zhe, Ding Biao, Li Qiang, Zheng Tianxiang, Ren Weili, Zhang Tianlong, Ren Yang, Zhong Yunbo, Liu C T, Gao Huajian, Zhu Yuntian
State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferromletallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China.
Department of Materials Science and Engineering, Hong Kong Institute for Advanced Study, City University of Hong Kong, Hong Kong, China.
Proc Natl Acad Sci U S A. 2025 Jan 14;122(2):e2409317121. doi: 10.1073/pnas.2409317121. Epub 2025 Jan 8.
The strength-ductility trade-off exists ubiquitously, especially in brittle intermetallic-containing multiple principal element alloys (MPEAs), where the intermetallic phases often induce premature failure leading to severe ductility reduction. Hierarchical heterogeneities represent a promising microstructural solution to achieve simultaneous strength-ductility enhancement. However, it remains fundamentally challenging to tailor hierarchical heterostructures using conventional methods, which often rely on costly and time-consuming processing. Here, we report a multiscale microstructural inheritance and refinement strategy to process "structural hierarchy precursors" in as-cast heterogeneous AlCoCrFeNi MPEAs, which lead directly to a hierarchical hetero-lamellar structure (HLS) after simple rolling and annealing. Interestingly, it takes only 10 min of annealing time, two orders of magnitude less than that required to render the state-of-the-art properties during conventional processing of AlCoCrFeNi, for us to achieve record-high strength-ductility combinations via the hierarchical HLS design that sequentially stimulates multiple unusual deformation and reinforcement mechanisms. In particular, the HLS-enabled high hetero-deformation-induced (HDI) internal stress triggers profuse <111>-type dislocations on over five independent slip systems in the supposedly brittle intermetallic phase and activates extensive stacking faults (SFs) and nanotwinning in the adjoining soft phase with a rather high SF energy. These unexpected, dynamically reinforcing hetero-deformation mechanisms across multiple length scales facilitate high sustained HDI strain hardening, along with a salient microcrack-mediated extrinsic ductilization effect, suggesting that the proposed microstructural inheritance and refinement strategy provides an efficient, fast, and low-cost approach to overcome the strength-ductility trade-off in a broad range of structural materials.
强度与延展性之间的权衡普遍存在，特别是在含有脆性金属间化合物的多主元合金（MPEA）中，其中金属间相常常引发过早失效，导致严重的延展性降低。分级异质性是实现强度与延展性同时提高的一种很有前景的微观结构解决方案。然而，使用传统方法来定制分级异质结构在根本上仍然具有挑战性，传统方法通常依赖于昂贵且耗时的加工过程。在此，我们报告一种多尺度微观结构继承与细化策略，用于在铸态异质AlCoCrFeNi MPEA中加工“结构分级前驱体”，经过简单轧制和退火后可直接形成分级异质层状结构（HLS）。有趣的是，仅需10分钟的退火时间，比在AlCoCrFeNi传统加工过程中获得现有最佳性能所需的时间少两个数量级，通过分级HLS设计依次激发多种异常变形和强化机制，我们就能实现创纪录的高强度与延展性组合。特别是，由HLS引发的高异质变形诱导（HDI）内应力在假定为脆性的金属间相中五个以上独立滑移系上触发大量<111>型位错，并在相邻软相中激活具有相当高堆垛层错能的广泛堆垛层错（SF）和纳米孪晶。这些跨多个长度尺度的意外动态强化异质变形机制促进了高持续HDI应变硬化，以及显著的微裂纹介导的外在延性化效应，这表明所提出的微观结构继承与细化策略提供了一种高效、快速且低成本的方法，以克服广泛结构材料中的强度与延展性之间的权衡。
