Uniting tensile ductility with ultrahigh strength via composition undulation.

Autor: Li H; Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, and College of Materials Science and Engineering, Jilin University, Changchun, China.; School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, Australia.; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China., Zong H; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China., Li S; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China., Jin S; Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, China., Chen Y; Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, and College of Materials Science and Engineering, Jilin University, Changchun, China., Cabral MJ; School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, Australia., Chen B; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China., Huang Q; School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, Australia., Chen Y; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China., Ren Y; Department of Physics, City University of Hong Kong, Kowloon, Hong Kong, China.; Centre for Neutron Scattering, City University of Hong Kong, Kowloon, Hong Kong, China., Yu K; Department of Materials Science and Engineering, China University of Petroleum-Beijing, Beijing, China., Han S; Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, and College of Materials Science and Engineering, Jilin University, Changchun, China. shuanghan@jlu.edu.cn., Ding X; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China. dingxd@mail.xjtu.edu.cn., Sha G; Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing, China. gang.sha@njust.edu.cn., Lian J; Key Laboratory of Automobile Materials (Jilin University), Ministry of Education, and College of Materials Science and Engineering, Jilin University, Changchun, China., Liao X; School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, Sydney, New South Wales, Australia. xiaozhou.liao@sydney.edu.au., Ma E; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China. maen@xjtu.edu.cn., Sun J; State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China.
Jazyk: angličtina
Zdroj: Nature [Nature] 2022 Apr; Vol. 604 (7905), pp. 273-279. Date of Electronic Publication: 2022 Apr 13.
DOI: 10.1038/s41586-022-04459-w
Abstrakt: Metals with nanocrystalline grains have ultrahigh strengths approaching two gigapascals. However, such extreme grain-boundary strengthening results in the loss of almost all tensile ductility, even when the metal has a face-centred-cubic structure-the most ductile of all crystal structures 1-3 . Here we demonstrate that nanocrystalline nickel-cobalt solid solutions, although still a face-centred-cubic single phase, show tensile strengths of about 2.3 gigapascals with a respectable ductility of about 16 per cent elongation to failure. This unusual combination of tensile strength and ductility is achieved by compositional undulation in a highly concentrated solid solution. The undulation renders the stacking fault energy and the lattice strains spatially varying over length scales in the range of one to ten nanometres, such that the motion of dislocations is thus significantly affected. The motion of dislocations becomes sluggish, promoting their interaction, interlocking and accumulation, despite the severely limited space inside the nanocrystalline grains. As a result, the flow stress is increased, and the dislocation storage is promoted at the same time, which increases the strain hardening and hence the ductility. Meanwhile, the segment detrapping along the dislocation line entails a small activation volume and hence an increased strain-rate sensitivity, which also stabilizes the tensile flow. As such, an undulating landscape resisting dislocation propagation provides a strengthening mechanism that preserves tensile ductility at high flow stresses.
(© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)
Databáze: MEDLINE
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