An atomistic study of the deformation behavior of tungsten nanowires

SZ Xu and YQ Su and DK Chen and LL Li, APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING, 123, 788 (2017).

DOI: 10.1007/s00339-017-1414-3

Large-scale atomistic simulations are performed to study tensile and compressive < 112 > loading of single-crystalline nanowires in body- centered cubic tungsten (W). Effects of loading mode, wire cross- sectional shape, wire size, strain rate, and crystallographic orientations of the lateral surfaces are explored. Uniaxial deformation of a W bulk single crystal is also investigated for reference. Our results reveal a strong tension-compression asymmetry in both the stress-strain response and the deformation behavior due to different yielding/failure modes: while the nanowires fail by brittle fracture under tensile loading, they yield by nucleation of dislocations from the wire surface under compressive loading. It is found that (1) nanowires have a higher strength than the bulk single crystal; (2) with a cross- sectional size larger than 10 nm, there exists a weak dependence of strength on wire size; (3) when the wire size is equal to or smaller than 10 nm, nanowires buckle under compressive loading; (4) the cross- sectional shape, strain rate, and crystallographic orientations of the lateral surfaces affect the strength and the site of defect initiation but not the overall deformation behavior.

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