Atomic scale investigation of nanocrack evolution in single-crystal and bicrystal metals under compression and shear deformation

QH Fang and J Li and H Luo and JK Du and B Liu, JOURNAL OF ALLOYS AND COMPOUNDS, 710, 281-291 (2017).

DOI: 10.1016/j.jallcom.2017.03.230

The objective of this work is to investigate the plastic deformation induced nanocrack evolution in single-crystal and bicrystal copper using molecular dynamics simulations, focusing on the effect of loading condition on crack closure. The results show that the compressive stress induced by defects such as dislocation, 9R phases and deformation twinning drives the crack closure. The microstructural evolution of nanocrack closure zone can be divided into four stages which include crack surface contact, local closure with discontinuously, closure zone expanding, and global closure. In addition, the crack in a bicrystal heals more easily than that in a single-crystal, due to the formation of a 9R phase. After one cyclic shear loading in both single-crystal and bicrystal copper, there is no crack nucleation in the crack closure zone. The MD results from this work may provide useful guidance for designing the optimal nanomaterial with high damage tolerance and long service life. (C) 2017 Elsevier B.V. All rights reserved.

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