Scale law of complex deformation transitions of nanotwins in stainless steel

• Published in: Nature communications Vol. 10; no. 1; p. 1403
• Main Authors: Chen, A. Y., Zhu, L. L., Sun, L. G., Liu, J. B., Wang, H. T., Wang, X. Y., Yang, J. H., Lu, J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.03.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 147/143; 639/301/1023/1026; 639/301/357/537; Austenitic stainless steels; Computer simulation; Deformation; Deformation mechanisms; Dislocations; Ductility; Humanities and Social Sciences; Lamella; Mechanical properties; Molecular dynamics; multidisciplinary; Science; Science (multidisciplinary); Stainless steel; Tensile tests; Twinning
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09360-1

Understanding the deformation behavior of metallic materials containing nanotwins (NTs), which can enhance both strength and ductility, is useful for tailoring microstructures at the micro- and nano- scale to enhance mechanical properties. Here, we construct a clear deformation pattern of NTs in austenitic stainless steel by combining in situ tensile tests with a dislocation-based theoretical model and molecular dynamics simulations. Deformation NTs are observed in situ using a transmission electron microscope in different sample regions containing NTs with twin-lamella-spacing ( λ ) varying from a few nanometers to hundreds of nanometers. Two deformation transitions are found experimentally: from coactivated twinning/detwinning ( λ  < 5 nm) to secondary twinning (5 nm <  λ  < 129 nm), and then to the dislocation glide ( λ  > 129 nm). The simulation results are highly consistent with the observed strong λ -effect, and reveal the intrinsic transition mechanisms induced by partial dislocation slip. The deformation mechanisms of twin boundaries in nanotwinned metallic materials are still unclear. Here the authors combine in situ transmission electron microscopy tensile tests and molecular dynamics simulations with a dislocation-based theoretical model to reveal the deformation mechanism of nanotwins.