Constitutive modeling for strain rate-dependent behaviors of nanocrystalline materials based on dislocation density evolution and strain gradient

To evaluate the influence of strain rate on mechanical behavior of nanocrystalline (NC) materials, a phase mixture constitutive model composed of ordered grain interior phase and plastically softer grain boundary dislocation pile up zone phase was built. Because of dissimilar properties and mismatch...

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Bibliographic Details
Published in:Journal of materials research 2014-12, Vol.29 (24), p.2982-2993
Main Authors: Wu, Youyi, Zhou, Jianqiu, Dong, Shuhong, Hu, Aosheng, Wang, Lu, Pang, Xuming
Format: Article
Language:English
Subjects:
Analysis
Applied and Technical Physics
Biomaterials
Composite materials
Constitutive relationships
Deformation
Dislocation density
Ductility
Evolution
Grain boundaries
Grain size
Inorganic Chemistry
Materials Engineering
Materials research
Materials Science
Mathematical models
Mechanical properties
Nanocrystals
Nanotechnology
Strain
Strain hardening
Strain rate
Studies
Tension tests
Yield stress
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Summary:To evaluate the influence of strain rate on mechanical behavior of nanocrystalline (NC) materials, a phase mixture constitutive model composed of ordered grain interior phase and plastically softer grain boundary dislocation pile up zone phase was built. Because of dissimilar properties and mismatch between the two phases, dislocation density evolution controlling mechanism based on statistically stored dislocations and geometrically necessary dislocations was analyzed and extended to NC regime to consider their disparate effects. Based on the composite model, a new stress–strain constitutive relation for strain rate-dependent behaviors was firstly established based on dislocation density evolution and strain gradient theory. The calculated data were then compared with corresponding experimental curves and strong strain rate-dependent behaviors were exhibited, which indicated that the predictions kept in good agreement with experiments. Further discussions were presented for calculations of strain rate sensitivity and activation volume for NC Ni through the proposed model.
ISSN:0884-2914
2044-5326
DOI:10.1557/jmr.2014.342