Correlating mechanical data with microstructural observations in deformation experiments on synthetic two-phase aggregates

Bloomfield, John P.; Covey-Crump, S. J.

doi:10.1016/0191-8141(93)90173-8

Cited by 43 publications

(31 citation statements)

References 15 publications

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“…Efforts to date to generalize relationships for the flow of multiphase system have often been inspired but have mostly been unsuccessful (Bloomfield and Covey-Crump 1993;Ji 2004;Treagus 2003;Tullis et al 1991). Predictably, the best quantitative models occur where phases have the least contrasting rheologies.…”

Section: Rheological Behavior Of Multiphase Systemsmentioning

confidence: 98%

Rheological and Thermal Properties of Icy Materials

et al. 2010

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Laboratory measurements of physical properties of planetary ices generate information for dynamical models of tectonically active icy bodies in the outer solar system. We review the methods for measuring both flow properties and thermal properties of icy planetary materials in the laboratory, and describe physical theories that are essential for intelligent extrapolation of data from laboratory to planetary conditions. This review is structured with a separate and independent section for each of the two sets of physical properties, rheological and thermal. The rheological behaviors of planetary ices are as diverse as the icy moons themselves. High-pressure water ice phases show respective viscosities that vary over four orders of magnitude. Ices of CO 2 , NH 3 , as well as clathrate hydrates of CH 4 and other gases vary in viscosity by nearly ten orders of magnitude. Heat capacity and thermal conductivity of detected/inferred compositions in outer solar system bodies have been revised. Some low-temperature phases of minerals and condensates have a deviant thermal behavior related to paramount water ice. Hydrated salts have low values of thermal conductivity and an inverse dependence of conductivity on temperature, similar to clathrate hydrates or glassy solids. This striking behavior may suit the dynamics of icy satellites.

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Section: Rheological Behavior Of Multiphase Systemsmentioning

confidence: 98%

Rheological and Thermal Properties of Icy Materials

et al. 2010

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“…It is noted that an ambiguity of a parameter ␣ can be eliminated or reduced if the stress/strain distribution of individual grains in a deformed sample is measured. 22,23 Let us compare the present theory with some experimental observations on MgO based on radial x-ray diffraction. The best results to compare with the present theory are those by Mei et al 24 where deformation experiments were made at T ͑temperature͒ = 1373-1573 K at P ͑pressure͒ = 1.5-10 GPa under which conditions deformation likely occurs by the power-law dislocation creep.…”

Section: Applications To Triaxial Compresion Of An Aggregate Of mentioning

confidence: 88%

“…Also a selfconsistent approach does not explain a behavior of aggregates when strength contrast is large. 17,22 The above theory is quite general, but replies on some assumptions. First, when deformation occurs at low temperatures and/or low stresses, then plastic deformation is not significant and the classical model by Singh 11 will apply.…”

Section: Discussionmentioning

confidence: 99%

Theory of lattice strain in a material undergoing plastic deformation: Basic formulation and applications to a cubic crystal

Karato

2009

Phys. Rev. B

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Theory of lattice strain in a polycrystalline aggregate under deviatoric stress is extended to include the influence of ongoing plastic deformation. When deviatoric stress is applied to a polycrystalline material at high temperatures ͑or above the yield stress͒, applied macroscopic stress is redistributed to individual grains by plastic deformation according to their orientations with respect to the macroscopic stress and plastic anisotropy of a given crystal. This microstress causes elastic deformation of individual grains that can be measured by x-ray diffraction. Consequently, the observed lattice strain depends on two material properties, viscosity ͑plas-ticity͒ and elastic compliance as well as the applied macroscopic stress and the stress-strain distribution among various grains. The influence of plastic deformation on lattice strain is analyzed using an anisotropic and nonlinear power-law constitutive relationship. In this model, the dependence of inferred macroscopic stress on the crystallographic orientation of diffraction plane ͑hkl͒ comes from elastic and plastic anisotropy of a crystal. In many materials, plastic anisotropy dominates over elastic anisotropy. This explains the observed large dependence of inferred stress on the diffraction plane and means that the determination of elastic anisotropy is difficult when plastic deformation occurs with anisotropic plasticity. When elastic anisotropy is known, plastic anisotropy of single crystal and/or stress-strain distribution in a deformed polycrystal can be determined from radial x-ray diffraction using the present model. Some examples are presented using the data on MgO.

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“…For the olivine + orthopyroxene rock this is

where, as above, ϕ ol and ϕ opx are the volume fractions of olivine and orthopyroxene, respectively, and σ and ε are the phase‐averaged stresses and strains, respectively, of the subscripted phases. Equations (3) and (4) may be derived from simple geometric considerations [e.g., Bloomfield and Covey‐Crump , 1993] and are widely found to give a good description of composite elastic properties when only the Young's modulus is of interest [e.g., Bogdanovich and Sierakowski , 1999]. For purely elastic deformation

where E is the Young's modulus of the subscripted phases parallel to the loading direction.…”

Section: Discussionmentioning

confidence: 99%

Using neutron diffraction to investigate the elastic properties of anisotropic rocks: Results from an olivine + orthopyroxene mylonite

et al. 2003

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[1] The penetrating power of neutrons means that neutron diffraction may be employed to determine the lattice parameters of mineral phases within samples over 1 cm in size. We have exploited this fact to obtain high-resolution measurements of the elastic strains experienced by olivine and orthopyroxene during room temperature, uniaxial deformation experiments performed in a neutron beam-line, on a mylonite from the Oman ophiolite. Specimens were loaded in three orthogonal directions with respect to the macroscopic fabric of the rock. In each case the average olivine and orthopyroxene strains were the same, even though the elastic stiffnesses of the two phases were different. In comparison with the strains expected from the single-crystal elastic stiffness tensors, the average strains in the different lattice directions for each phase were found to be greater in the stiffer directions, and lesser in the more compliant directions. The overall effect of this tendency toward strain homogenization was for the measured elastic anisotropy of the rock to be significantly lesser than that given by Voigt/Reuss averaging of the singlecrystal elastic properties according to the lattice preferred orientations of each phase. The technique used to derive these conclusions potentially provides an important experimental method for the quantitative examination of nonfracture-related controls on the elastic anisotropy of geological materials.INDEX TERMS: 3909 Mineral Physics: Elasticity and anelasticity; 3954 Mineral Physics: X ray, neutron, and electron spectroscopy and diffraction; 5194 Physical Properties of Rocks: Instruments and techniques; 5112 Physical Properties of Rocks: Microstructure; 7218 Seismology: Lithosphere and upper mantle; KEYWORDS: neutron diffraction, elastic properties, elastic anisotropy, Oman ophiolite, mechanical properties of composite materials Citation: Covey-Crump, S. J., P. F. Schofield, I. C. Stretton, K. S. Knight, and W. Ben Ismaïl, Using neutron diffraction to investigate the elastic properties of anisotropic rocks: Results from an olivine + orthopyroxene mylonite,

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Correlating mechanical data with microstructural observations in deformation experiments on synthetic two-phase aggregates

Cited by 43 publications

References 15 publications

Rheological and Thermal Properties of Icy Materials

Rheological and Thermal Properties of Icy Materials

Theory of lattice strain in a material undergoing plastic deformation: Basic formulation and applications to a cubic crystal

Using neutron diffraction to investigate the elastic properties of anisotropic rocks: Results from an olivine + orthopyroxene mylonite

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