Auxetic crystals under stress: Peering into their mechanics using x-rays

摘要: The discovery of auxetic behavior (negative Poisson's ratio) within elements and alloys had focused attention on their elastic anisotropy in an effort to understand the range crystal orientations that manifest this property. A comparison constant data atomistic models based pair-wise, central force provides key insights into deformation cubic crystals over a wide anisotropy, including, for first time, those with Zener ratios less than 1. simple criterion is derived which dictates all cases whose atomic ordering obeys symmetry will display deformation, where extrema ratio involves (110) orientations. In field stress determination through x-ray diffraction, these findings also shed light strain polycrystalline materials, incompatibility between adjacent grains alters overall deformation. By applying same models, we can predict Voigt/Reuss weighting fractions associated Kroner limit constants necessary component quantifying using diffraction data. We establish greater constituent leads more rigid mechanical response corresponding aggregate, implications ensembles.