Micromechanical simulation of fracture behavior of bimodal nanostructured metals

Nanostructured (NS) metals with bimodal grain size distribution that consist of coarse grained (CG) and nano-grained (NG) regions have proved to have both high strength and good ductility. In this paper a numerical investigation, using the combination of a mechanism-based strain gradient plasticity...

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2014-11, Vol.618, p.479-489
Main Authors: Guo, X., Ji, R., Weng, G.J., Zhu, L.L., Lu, J.
Format: Article
Language:English
Subjects:
Applied sciences
Bimodal grain size distribution
Copper
Cross-disciplinary physics: materials science
rheology
Deformation, plasticity, and creep
Elasticity. Plasticity
Exact sciences and technology
Fracture mechanics
Fracture resistance
Fracture toughness
Fractures
Inclusions
Johnson–Cook failure model
Materials science
Mathematical models
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Mechanism-based strain gradient plasticity
Metals. Metallurgy
Micromechanics composite model
Microstructure
Nanostructure
Physics
Strain
Treatment of materials and its effects on microstructure and properties
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Summary:Nanostructured (NS) metals with bimodal grain size distribution that consist of coarse grained (CG) and nano-grained (NG) regions have proved to have both high strength and good ductility. In this paper a numerical investigation, using the combination of a mechanism-based strain gradient plasticity theory, a micromechanics composite model, and the Johnson–Cook failure model, is conducted to investigate the effects of the distribution of the CG inclusions and their shape on fracture behavior of a bimodal NS copper. Load–response relations are employed to evaluate the loading history stability, while apparent crack length and strain energy history are used to analyze the fracture resistance. This study shows that both crack bridging in the CG inclusions and crack deflection in the NG matrix can significantly toughen the bimodal NS Cu. Our simulations also show that there exists a critical volume fraction of CG inclusions for some microstructures at which the fracture resistance of the bimodal NS Cu is at its minimal state and thus it should be avoided in material design.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2014.09.036