Ultrahigh strength and ductility in newly developed materials with coherent nanolamellar architectures

Lei Fan,Yilu Zhao,Junhua Luan,Zengbao Jiao,Chain-Tsuan Liu,Gang Zhou,Hao Wang,Tao Yang

doi:10.1038/s41467-020-20109-z

Abstract

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.

Highlights

Nano-lamellar materials with ultrahigh strengths and unusual physical properties are of technological importance for structural applications
Developing ultrahigh strength, ductile, and scalable nanolamellar alloys are highly desirable but extremely challenging. We overcome these critical challenges and present the development of new nanolamellar alloys featuring in situ-formed coherent nanolamellar (CNL) architectures, which exhibit an unprecedented combination of ultrahigh strength and tensile ductility and can be produced through conventional casting and thermomechanical treatments
The ultrahigh strength CNL alloy shows a large tensile ductility, with a uniform elongation of 16%, which is an order of magnitude larger than that of the severe deformed alloy with high dislocation densities (~1% uniform elongation)

Summary

Introduction

Nano-lamellar materials with ultrahigh strengths and unusual physical properties are of technological importance for structural applications These materials generally suffer from low tensile ductility, which severely limits their practical utility. Nanolamellar alloys containing high-density interfaces are of particular interest owing to their unusual interface-driven properties, such as extremely high strengths[1,2,3,4,5,6,7,8] These materials typically suffer from a severe limitation—lack of tensile ductility, typically

Methods

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Conclusion