AbstractInspired by the gradient structures of biological materials, researchers have explored compositional and structural gradients for about 40 years as an approach to enhance the properties of engineering materials, including metals and metallic alloys. The synthesis of various gradient nanostructured materials, such as gradient nanograined, nanolaminated nd nanotwinned metals and alloys, has provided new opportunities to understand gradient-related mechanical behaviour. These emerging gradient materials often exhibit unprecedented mechanical properties, such as strength鈥揹uctility synergy, extraordinary strain hardening, enhanced fracture and fatigue resistance, and remarkable resistance to wear and corrosion, which are not found in materials with homogeneous or random microstructures. This Review critically assesses the state of the art in the field of gradient nanostructured metallic materials, covering topics ranging from the fabrication and characterization of mechanical properties to underlying deformation mechanisms. We discuss various deformation behaviours induced by structural gradients, including stress and strain gradients, the accumulation and interaction of new dislocation structures, and unique interfacial behaviour, as well as providing insight into future directions for the development of gradient structured materials. Subscribe to JournalGet full journal access for 1 year55,14 鈧?/p>only 4,60 鈧?per issueSubscribeAll prices are NET prices. VAT will be added later in the checkout.Tax calculation will be finalised during checkout.Rent or Buy articleGet time limited or full article access on ReadCube.from$8.99Rent or BuyAll prices are NET prices. Fig. 1: Types of structural and chemical gradients in typical gradient materials.Fig. 2: Surface mechanical treatment methods.Fig. 3: Microstructure of gradient nanograined, gradient nanolaminated and gradient nanotwinned metals.Fig. 4: Comparison of the mechanical properties of gradient nanostructured and homogeneous metals and alloys.Fig. 5: Comparison of fatigue and friction behaviour in gradient nanostructured and homogeneous metals and alloys.Fig. 6: Deformation mechanisms in gradient nanostructured metals and alloys.Fig. 7: Open issues and challenges for gradient nanostructured metals and alloys. References1.Liu, Z., Meyers, M. A., Zhang, Z. Ritchie, R. O. Functional gradients and heterogeneities in biological materials: design principles, functions, and bioinspired applications. Prog. Mater. Sci. 88, 467鈥?98 (2017).CAS聽Google Scholar聽 2.Suresh, S. Graded materials for resistance to contact deformation and damage. 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Z180014) and the National Science and Technology Major Project (grant no. 2017-VI-0003鈥?073).Author informationAffiliationsCenter for Advanced Mechanics and Materials, Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing, ChinaXiaoyan Li,聽Jianguo Li聽 聽Xuan ZhangShenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, ChinaLei LuSchool of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore, SingaporeHuajian GaoInstitute of High Performance Computing, A*STAR, Singapore, SingaporeHuajian GaoAuthorsXiaoyan LiView author publicationsYou can also search for this author in PubMed聽Google ScholarLei LuView author publicationsYou can also search for this author in PubMed聽Google ScholarJianguo LiView author publicationsYou can also search for this author in PubMed聽Google ScholarXuan ZhangView author publicationsYou can also search for this author in PubMed聽Google ScholarHuajian GaoView author publicationsYou can also search for this author in PubMed聽Google ScholarContributionsX.L., L.L. and H.G. discussed the content. All authors contributed to the writing, reviewing and editing of the manuscript.Corresponding authorCorrespondence to Huajian Gao.Ethics declarations Competing interests The authors declare no competing interests. Additional informationPublisher鈥檚 noteSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Rights and permissionsReprints and PermissionsAbout this articleCite this articleLi, X., Lu, L., Li, J. et al. Mechanical properties and deformation mechanisms of gradient nanostructured metals and alloys. Nat Rev Mater 5, 706鈥?23 (2020). https://doi.org/10.1038/s41578-020-0212-2Download citationAccepted: 21 May 2020Published: 08 July 2020Issue Date: September 2020DOI: https://doi.org/10.1038/s41578-020-0212-2 J. H. Zhang, X. M. Liu, G. S. Zhang, W. K. Deng, J. Y. Hao, M. Li D. F. Guo Journal of Materials Science (2021) Sign up for the Nature Briefing newsletter 鈥?what matters in science, free to your inbox daily.