Critical Strengths for Slip Events in Nanocrystalline Metals: Predictions of Quantized Crystal Plasticity Simulations |
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Authors: | Lin Li Myoung-Gyu Lee Peter M Anderson |
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Affiliation: | (1) Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210, USA;(2) Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang, Gyeongbuk, 790-784, Korea; |
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Abstract: | This article studies how the monotonic and cyclic stress-strain response of nanocrystalline (NC) metals is affected by the
grain-to-grain distribution of critical strengths (τ
c
) for slip events, as well as plastic predeformation (ε
pre
p
). This is accomplished via finite element simulations that capture large jumps in plastic strain from dislocation slip events—a process referred to
as quantized crystal plasticity (QCP).1] The QCP simulations show that τ
c
and ε
pre
p
significantly alter the monotonic and cyclic response at small strain, but only τ
c
affects the response at large strain. These features are exploited to systematically infer the τ
c
and ε
pre
p
characteristics that best fit experimental data for electrodeposited (ED) NC Ni. Key outcomes are the following: (1) the
τ
c
distribution is truncated, with an abrupt onset of slip events at a critical stress; (2) ε
pre
p
= −0.4 pct, signifying precompression; (3) there is reverse slip bias, meaning that reverse slip events are easier than forward
events; and (4) highly inhomogeneous residual stress states can be enhanced or reduced by tensile deformation, depending on
ε
pre
p
. |
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Keywords: | |
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