Showing papers by "Donald J. Weidner published in 2004"
TL;DR: San-Carlos olivine rheology was investigated at pressure (P) up to 9 GPa and temperature (T) lower than 890 C in this article.
99 citations
TL;DR: In this article, uniaxial deformation experiments on polycrystalline and single-crystal MgO samples were conducted in situ using white x-ray diffraction with a multielement detector and multianvil high-pressure apparatus at a pressure up to 6 GPa and a temperature of 500 °C.
Abstract: 3^011& at different critical resolved shear stress ratios for the different slip systems. The prediction of the models is correlated with the results of x-ray diffraction measurements. Uniaxial deformation experiments on polycrystalline and single-crystal MgO samples were conducted in situ using white x-ray diffraction with a multielement detector and multianvil high-pressure apparatus at a pressure up to 6 GPa and a temperature of 500 °C. A deformation DIA was used to generate pressure and control at a constant deformation rate. Elastic strains and plastic strains were monitored using x-ray diffraction spectra and x-ray imaging techniques, respectively. The correlation of the data and models suggests that the plastic models need to be used to describe the stress‐strain observations with the presence of plasticity, while the Reuss and Voigt models are appropriate for the elastic region of deformation, before the onset of plastic deformation. The similarity of elastic strains among different lattice planes suggests that the $111% slip system is the most significant slip system in MgO at high pressure and high temperature. © 2004 American Institute of Physics. @DOI: 10.1063/1.1738532#
80 citations
TL;DR: In this paper, the authors report an experimental study of plastic deformation of San Carlos olivine (Mg, Fe) 2 SiO 4 under upper mantle conditions using a multi-anvil press.
69 citations
TL;DR: Weidner et al. as discussed by the authors measured elastic strain anisotropy induced by a macroscopic differential stress in an aggregate sample and found that the results were consistent with the predictions of a self-consistent aggregate model for deforming polycrystals.
Abstract: [1] Recent developments in high-pressure X-ray studies enable the measurement of the elastic strain anisotropy induced by a macroscopic differential stress in an aggregate sample. Such data are commonly used to constrain the single-crystal elastic moduli under the assumptions of the Reuss-Voigt state. We find this procedure is valid only for samples that have not been plastically deformed. Measured elastic strain anisotropy for MgO at stress levels below the yield point agree well with the Reuss elastic model. Plastic deformation effects a change in the stress field for subpopulations of grains that represent different crystallographic orientations with respect to the applied stress field. Our data for the plastically deformed sample are consistent with the predictions of a self-consistent aggregate model for deforming polycrystals. Such models may be useful as a guide to define the elastic properties in light of the active slip systems. INDEX TERMS: 3902 Mineral Physics: Creep and deformation; 3909 Mineral Physics: Elasticity and anelasticity; 3924 Mineral Physics: High-pressure behavior; 3954 Mineral Physics: X ray, neutron, and electron spectroscopy and diffraction; 3994 Mineral Physics: Instruments and techniques. Citation: Weidner, D. J., L. Li, M. Davis, and J. Chen (2004), Effect of plasticity on elastic modulus measurements, Geophys. Res. Lett., 31, L06621, doi:10.1029/ 2003GL019090.
69 citations
TL;DR: In this paper, an experimental technique for in situ stress and strain measurements at high pressure and temperature using synchrotron X-rays has been developed at the X17B beamline of the National Synchoretron Light Source.
54 citations