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Showing 1 to 20 of 25 for “"Dislocation creep"”.
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Continuum Damage Mechanics (CDM) modelling of dislocation creep in 9-12% Cr creep resistant steels
… material properties specifically that of creep degradation and deformation. This has been partially due to the reliance of creep life predictions in the past being based on accelerated creep testing and empirically based modelling. With the relatively recent revelations of empirically …
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High temperature creep behavior of Inconel 617 and Haynes 230
… on the biaxial, long term, high temperature creep behavior for Alloy 617 and Alloy 230. The creep mechanisms, including dislocation creep and grain boundary sliding, were found for the stress range of 10 to 55 MPa at 850oC, 900oC and 950oC for Alloy 617. In the contrast, only dislocation …
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Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle
… with depth assuming a composite diffusion-dislocation creep rheology. We investigate the importance of water content by examining end-member models for a dry, wet, and dehydrated mantle (with dehydration above ~60-70 km depth). We find that grain size increases with depth, and varies with …
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Influence of grain size evolution and water content on the seismic structure of the oceanic upper mantle
… with depth assuming a composite diffusion-dislocation creep rheology. We investigate the importance of water content by examining end-member models for a dry, wet, and dehydrated mantle (with dehydration above -60-70 km depth). We find that grain size increases with depth, and varies with …
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Silicon and oxygen self-diffusion in forsterite and implications to upper-mantle rheology
… in dry forsterite The high temperature creep of olivine is believed to be controlled by self-diffusion of olivine. However, the experimentally measured silicon diffusion coefficients (DSi) [Dohmen et al., 2002; Jaoul et al., 1981] were about 2-3 orders of magnitude lower than those …
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The role and fate of fluid inclusions in natural and experimental deformation
… fulfill these conditions: olivine deforms in the dislocation creep regime, and the assemblage olivine + water is stable at that temperature. Therefore, olivine is used in the experimental part of this project; results obtained from olivine experiments can help understand the physical processes …
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Mechanisms of Shear Zone Localization and Raman Thermobarometry in Spinel Peridotites from the Alpine Fault, New Zealand
… Fault. The first set of samples has evidence of dislocation creep with subgrains, recrystallized grains, undulose extinction and a lattice preferred orientation. These samples also show evidence of post deformation static grain growth with polygonal grains, 120° triple junctions, and euhedral …
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Deformation mechanisms of naturally deformed rocksalt
… samples. The main deformation mechanisms are dislocation processes and solution-precipitation in the Hengelo samples, while the samples from Neuhof-Ellers deform solely by solution-precipitation creep due to its very fine grain size (~1 mm). In both set of samples, widespread evidence for …
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Geochemical and rheological constraints on the dynamics of the oceanic upper mantle
… grain annealing. Upper mantle flow is by dislocation creep, resulting in seismic anisotropy due to mineral alignment. I use a shear zone in the Josephine Peridotite to quantify the relationship between mineral orientation and shear strain, providing an improved framework for the …
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Geochemical and rheological constraints on the dynamics of the oceanic upper mantle
… grain annealing. Upper mantle flow is by dislocation creep, resulting in seismic anisotropy due to mineral alignment. I use a shear zone in the Josephine Peridotite to quantify the relationship between mineral orientation and shear strain, providing an improved framework for the …
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Plagioclase preferred orientation in layered mylonites : evaluation of flow laws for the lower crust
… exhibit strong LPOs indicating they deform by dislocation creep. Plagioclase grain size in mixed plagioclase-pyroxene mylonite layers is finer than in pure plagioclase layers, and depends on the size and proportion of pyroxenes. Progressive mixing of pyroxene and plagioclase within gabbro …
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Plagioclase preferred orientation in the layered mylonites : evaluation of flow laws for the lower crust
… exhibit strong LPOs indicating they deform by dislocation creep. Plagioclase grain size in mixed plagioclase-pyroxene mylonite layers is finer than in pure plagioclase layers, and depends on the size and proportion of pyroxenes. Progressive mixing of pyroxene and plagioclase within gabbro …
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Piezometry and Strain Rate Estimates Along Mid-Crustal Shear Zones
… distance. Strain rates estimated with quartz dislocation creep flow laws are tectonically reasonable, between 10⁻¹² – 10⁻¹⁴ s⁻¹. Traced towards each shear zone strain rate estimates first decrease one order of magnitude before rapidly increasing one to two orders of magnitude at structural …
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Stress and strain rate estimates associated with penetrative deformation of the Harkless quartzite aureole rocks, Papoose Flat Pluton, California/Using structure contour maps to analyze subsurface 3D fault geometry along segments of the Moine Thrust
… between ~11 and ~29 MPa. Published wet-quartzite dislocation creep flow laws combined with deformation temperature, water fugacity, and differential stress estimates infer strain rates that range from 1.2 x 10⁻¹⁴ s⁻¹ to 2.3 x 10⁻¹² s⁻¹. In order to analyze 3D subsurface fault geometry along …
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Flow Properties of Moine Thrust Zone Mylonites in Northern Assynt, NW Scotland
… flow stress data were then incorporated into a dislocation creep flow law for quartz to estimate strain rates. Finally, along strike variation in these flow properties at the base of the Moine nappe to the north and south of the APM section were investigated and results from the APM section …
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Structural analysis of the Paint Lake Deformation Zone, Northern Ontario /
… microstructural deformation mechanism from dislocation creep to diffusion creep is observed with increasing strain during mylonitization. C'-fabric development is temporally associated with this change. A decrease in the angular relationship between C- and C'-fabrics is observed upon …
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Creep resistance of directionally solidified eutectic ceramics : experiments and model
The creep resistance of the directionally solidified eutectic ceramic of Al₂0₃/c-ZrO₂(Y₂0₃) was studied in the temperature range of 1200-1520⁰C both exprimentally and by the mechanistic dislocation model. The topologically continuous majority phase of Al₂0₃ has a nearly perfect growth texture in …
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High temperature deformation mechanisms and strain heterogeneities in calcite rocks
… increases the strength of calcite rocks during dislocation creep. The anisotropic nature of crystal slip usually entails variations in reorientation of individual grains and heterogeneous deformation within the polycrystalline material. In Chapter 3, a new technique including a series of sample …
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Deformation Mechanisms and Strain Localization in the Mafic Continental Lower Crust
… This fine-grained mixture deforms by diffusion creep, causing significant rheological weakening. Case-study 2 investigates a lower crustal shear zone in a compositionally-layered mafic complex made of amphibole-rich and amphibole-poor metagabbros. Findings of case-study 2 show that during …
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Simulation of creep in nickel based single crystal superalloys
… of their superior high-temperature strength and creep properties as compared to the other materials. This is due to two factors: solid solution and precipitation strengthening of the gamma ([gamma]) and gamma prime ([gamma]') phases, and the elimination of grain boundaries. Creep of Nickel based …
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