Molecular dynamics simulation studies on the size dependent tensile deformation and fracture behaviour of body centred cubic iron nanowires

G Sainath and BK Choudhary and T Jayakumar, COMPUTATIONAL MATERIALS SCIENCE, 104, 76-83 (2015).

DOI: 10.1016/j.commatsci.2015.03.053

Tensile deformation behaviour of body centred cubic (BCC) iron nanowires with initial orientation of < 100 >/100 has been investigated using molecular dynamics (MD) simulations. MD simulations were performed at 10 K employing a strain rate of 1 x 10(8) s(-1) for the nanowires with cross section width (d) ranging from 1.42 to 24.27 nm. BCC Fe nanowires exhibited two different behaviours as a function of size. Young's modulus, and yield and flow stresses decreased rapidly with increase in nanowire size up to 11.42 nm followed by gradual decrease approaching towards saturation at larger size. The < 100 >/ 100 nanowires up to 11.42 nm size deform by twinning at low strains and undergo twinning mediated reorientation to < 110 >/112 configuration. The reoriented nanowires deform by slip mode at high strains resulting in high ductility and failure by necking. Beyond 11.42 nm size, the reorientation mechanism ceases to operate and the nanowires deform only by twinning exhibiting low ductility and failure by cleavage. The size dependent deformation behaviour has been discussed in terms of the number of active slip systems operating during deformation in Fe nanowires. (C) 2015 Elsevier B.V. All rights reserved.

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