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Variability of Poisson's Ratio and Enhanced Ductility in Amorphous Metal
Author(s) -
Liss KlausDieter,
Qu Dongdong,
Yan Kun,
Reid Mark
Publication year - 2013
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201200216
Subject(s) - materials science , amorphous metal , poisson's ratio , diffraction , deformation (meteorology) , condensed matter physics , diffusionless transformation , shear modulus , ductility (earth science) , amorphous solid , composite material , transverse plane , crystallography , martensite , poisson distribution , optics , microstructure , physics , statistics , mathematics , creep , alloy , chemistry , structural engineering , engineering
Ductile bulk metallic glass of composition 53.0Zr–18.7Cu–12.0Ni–16.3Al (at%) is plastically deformed under uniaxial compression and observed in situ by synchrotron high‐energy X‐ray diffraction. The diffraction patterns reveal the induced atomic strain is orientation dependent. At the onset of plastic deformation, the atomic strain in the compression direction saturates to a close‐nearest‐neighbor distance while atoms relax in the transverse direction. The ever increasing transverse atomic strain expresses in an augmentation of the apparent Poisson's ratio up to ν = 0.5, which is consistent with volume conservation. Contradicting phenomena from linear mechanics, such as the non‐vanishing shear modulus at ν = 0.5 can be explained by the non‐affine character of the deformation, giving rise to characteristics of a localized martensitic phase transformation. The findings explain the often‐reported phenomena such as, the high Poisson's ratio values found in metallic glasses, the partially liquid character of the structure, the free volume increase and the Bauschinger effect.