Ultrastrong nanotwinned pure nickel with extremely fine twin thickness

作者：Fenghui Duan, Yan Lin, Jie Pan, Lei Zhao, Qiang Guo, Di Zhang, Y. Li · 发表于：Science Advances · 年份：2021 · DOI：10.1126/sciadv.abg5113 · 被引用次数：149 · 研究领域：Microstructure and mechanical properties、Metal and Thin Film Mechanics、Boron and Carbon Nanomaterials Research

The strength of nanocrystalline and nanotwinned metals stops increasing or even starts decreasing when their grain size or twin thickness is below a critical size-a phenomenon known as Hall-Petch breakdown-which hinders the attainment of ultrahigh strength. Here, we report continuous strengthening in nanotwinned pure Ni with twin thicknesses ranging from 81.0 to 2.9 nm. An unprecedented strength of 4.0 GPa was achieved at extremely fine twin thickness of 2.9 nm, which is about 12 times stronger than that of conventional coarse-grained nickel. This ultrahigh strength arises from the excellent stability of twin boundaries and their strong impedance to dislocation motion. In particular, we find that secondary nanotwins are activated to sustain plastic deformation, which also contribute to the high strength. These results not only advance the understanding of the strengthening mechanisms in nanotwinned metals but also offer an alternative pathway to develop engineering materials with ultrahigh strength.