Molecular dynamics simulations of tension-compression asymmetry in nanocrystalline copper

K Zhou and SF Shao and YJ Yao, PHYSICS LETTERS A, 381, 1163-1168 (2017).

DOI: 10.1016/j.physleta.2017.01.027

Molecular dynamics simulations are used to investigate uniaxial tension and compression of nanocrystalline copper with mean grain sizes of 3.8-11.9 nm. The simulation resifts show an apparent asymmetry in the flow stress, with nanocrystalline copper stronger in compression than in tension. The asymmetry exhibits a maximum at the mean grain size of about 10 nm. The dominant mechanism of the asymmetry depends on the mean grain size. At small grain sizes, grain-boundary based plasticity dominates the asymmetry, while for large grain sizes the asymmetry mainly arises from the pressure dependent dislocation emission from grain boundaries. (C) 2017 Elsevier B.V. All rights reserved.

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