期刊
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
卷 110, 期 -, 页码 260-268出版社
JOURNAL MATER SCI TECHNOL
DOI: 10.1016/j.jmst.2021.09.032
关键词
Shear band; Laminated metallic composites; Ductility; High-energy X-ray diffraction; Dislocation slip
资金
- National Natural Science Foundation of China [51922026]
- Fundamental Research Funds for the Central Universities [N20 020 05, N2007011]
- 111 Project [B20029]
- Czech Ministry of Education, Youth and Sports (infrastructure ESS Scandinavia-CZ) project [LM2018111]
- China Scholarship Council
Shear bands in metallic materials, especially those with hexagonal-close-packed (hcp) constituents, typically result in non-uniform plastic deformation. This study proposes a counterintuitive design strategy that tolerates shear bands with localized strains, known as the shear banded laminar (SBL) structure, which promotes ( c + a ) dislocation activation in hcp metals and achieves unprecedented strength and ductility combination in hcp-metal-based composites.
Shear bands in metallic materials have been reported to be catastrophic because they normally lead to non-uniform plastic deformation. Ductility of laminated metallic composites deteriorates with increasing processing strain, particularly for those having hexagonal-close-packed (hcp) constituents due to inadequate slip systems and consequently prominent shear banding. Here, we propose a design strategy that counterintuitively tolerates the bands with localized strains, i.e. the shear banded laminar (SBL) structure, which promotes ( c + a ) dislocation activation in hcp metals and renders unprecedented strengthductility combination in hcp-metal-based composites fabricated by accumulative roll bonding (ARB). The SBL structure is characterized with one soft hcp metal constrained by adjacent hard metal in which dislocations have been accumulated near the bimetal interfaces. High-energy X-ray diffraction astonishingly reveals that more than 90% of dislocations are non-basal in Ti layers of the SBL Ti/Nb composite processed by eight ARB cycles. Moreover, ( c+a ) dislocations occupy a high fraction of -30%, promoting further ( c+a ) cross slip. The unique stress field tailored by both shear banding and heterophase interface-mediated deformation accommodation triggers important ( c+a ) slip. This SBL design is of significance for developing hcp-based laminates and other heterostructured materials with high performances.
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