A constitutive model of nanocrystalline metals based on competing grain boundary and grain interior deformation mechanisms |
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Authors: | Ercan Gürses Tamer El Sayed |
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Affiliation: | 1. Impact and Crashworthiness Laboratory, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge MA, USA;2. Institute of Virtual Manufacturing, Swiss Federal Institute of Technology (ETH Zurich), Tannenstrasse 3, Zurich 8092, Switzerland;3. 77 Cheongam-ro, Nam-gu, Pohang, Gyeongbuk 37673, Republic of Korea |
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Abstract: | In this work, a viscoplastic constitutive model for nanocrystalline metals is presented. The model is based on competing grain boundary and grain interior deformation mechanisms. In particular, inelastic deformations caused by grain boundary diffusion, grain boundary sliding and dislocation activities are considered. Effects of pressure on the grain boundary diffusion and sliding mechanisms are taken into account. Furthermore, the influence of grain size distribution on macroscopic response is studied. The model is shown to capture the fundamental mechanical characteristics of nanocrystalline metals. These include grain size dependence of the strength, i.e., both the traditional and the inverse Hall–Petch effects, the tension–compression asymmetry and the enhanced rate sensitivity. |
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