Fan Lei, Yang Tao, Zhao Yilu, Luan Junhua, Zhou Gang, Wang Hao, Jiao Zengbao, Liu Chain-Tsuan
Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China.
Nat Commun. 2020 Dec 7;11(1):6240. doi: 10.1038/s41467-020-20109-z.
Nano-lamellar materials with ultrahigh strengths and unusual physical properties are of technological importance for structural applications. However, these materials generally suffer from low tensile ductility, which severely limits their practical utility. Here we show that markedly enhanced tensile ductility can be achieved in coherent nano-lamellar alloys, which exhibit an unprecedented combination of over 2 GPa yield strength and 16% uniform tensile ductility. The ultrahigh strength originates mainly from the lamellar boundary strengthening, whereas the large ductility correlates to a progressive work-hardening mechanism regulated by the unique nano-lamellar architecture. The coherent lamellar boundaries facilitate the dislocation transmission, which eliminates the stress concentrations at the boundaries. Meanwhile, deformation-induced hierarchical stacking-fault networks and associated high-density Lomer-Cottrell locks enhance the work hardening response, leading to unusually large tensile ductilities. The coherent nano-lamellar strategy can potentially be applied to many other alloys and open new avenues for designing ultrastrong yet ductile materials for technological applications.
具有超高强度和异常物理性能的纳米层状材料在结构应用方面具有重要的技术意义。然而，这些材料通常拉伸延展性较低，这严重限制了它们的实际应用。在此我们表明，在相干纳米层状合金中可实现显著增强的拉伸延展性，这些合金展现出超过2吉帕屈服强度和16%均匀拉伸延展性这一前所未有的组合。超高强度主要源于层状边界强化，而大延展性与由独特纳米层状结构调控的渐进加工硬化机制相关。相干层状边界促进位错传输，消除了边界处的应力集中。同时，形变诱导的分级堆垛层错网络及相关的高密度洛默 - 科特雷尔位错锁增强了加工硬化响应，导致异常大的拉伸延展性。相干纳米层状策略有可能应用于许多其他合金，并为设计用于技术应用的超强且具延展性的材料开辟新途径。
