Grain-boundary sliding and its accommodation during creep and superplasticity

Gifkins, R. C.

doi:10.1007/bf02656607

Cited by 648 publications

(202 citation statements)

References 22 publications

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“…Assuming that the temperature of 600 ~ was maintained for i> 10 Ma, the upper limiting value of D gb given in Table I is obtained from equation (5) The final diffusion coefficient listed in Table I is for Mg2GeO4 spinel, which may be a good analogue for the corresponding silicate phase. The diffusion coefficient has been estimated by fitting the superplastic creep data for fine-grained (d = 3 #m) spinel of Vaughan and Coe (1981) to the flow law 82b3Dgb3 etr = (6) ~kT where g is the strain rate, b is the Burgers vector, and a is the differential stress (Gifkins, 1976). An alternative flow law (Gifkins, 1976, equation 4a) gives an almost identical value for D gb.…”

Section: Grain Boundary Diffusionmentioning

confidence: 99%

The catalysis of mineral reactions by water and restrictions on the presence of aqueous fluid during metamorphism

1986

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ABSTRACT, The problems of characterizing intergranular regions and of estimating rates of intergranular diffusion in metamorphic rocks are discussed. Intergranular regions can be anhydrous, hydrated but undersaturated with H20, or saturated with H20, but only in the latter case can a free aqueous fluid phase be present. Estimates of intergranular diffusion coefficients (D mR) at 550 ~ derived from a variety of published experimental work, vary from ~ 10 -8 m 2 s -1 for diffusion of species through an intergranular fluid film to ~< 4 • 10-24 m 2 s 1 for diffusion of SiO2 or O in anhydrous grain boundaries in quartzite. Estimates of D mR for hydrated grain boundaries vary from ~ 10 -13 m 2 s -1 to ~ 10 -zl m 2 s 1; the concentration of H20 in the grain boundaries and the identity of the diffusing species (generally unknown) may be important controlling factors, and there exists the possibility of a spectrum of values between these two extremes.Using available kinetic data it is shown that a free aqueous fluid could never have been present in parts of the basement terrane of the Sesia Zone (Western Alps) during uplift from the eclogite facies, except possibly late in the cooling history. The breakdown of sodic pyroxene+ quartz occurred in response to the localized infiltration of catalytic aqueous fluid, possibly over a time interval as short as 6-6000 a, and possibly under conditions remote from equilibrium. H20-present conditions during a dehydration reaction in metapelites of the Adula nappe (central Alps) could also have been of short duration. These examples are consistent with a model in which basement rocks at deep crustal levels are dry for long periods of time and in which the development of equilibrium mineral assemblages and microstructures generally occurs over relatively short periods of time under transitory fluid-present conditions (caused by devolatilization and/or infiltration).

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Section: Grain Boundary Diffusionmentioning

confidence: 99%

The catalysis of mineral reactions by water and restrictions on the presence of aqueous fluid during metamorphism

1986

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“…Subgrain rotation recrystallization (SGR) occurs at higher temperatures (Hirth and Tullis 1992) (400-500°C for quartz) (Passchier and Trouw 2005) and is characterized by ductility deformed, elongated and ribbon-shaped parent grains with many subgrains. As a result of this process the remains of old grains are commonly surrounded by groups of recrystallized grains (a feature known as a core-and-mantle structure in Gifkins 1976;White 1976;Shigematsu 1999) or may be completely replaced by recrystallized material (Hirth and Tullis 1992;Stipp et al 2002). High temperature grain-boundary migration recrystallization (GBM) (Hirth and Tullis 1992) (500 to \700°C for quartz) is characterized by grains with new, lobate grain boundaries (Vernon 2004;Passchier and Trouw 2005).…”

Section: Introductionmentioning

confidence: 99%

Localisation of ductile and brittle shear zones along the Szentlőrinc-1 well in the Mecsekalja Zone using quartz microstructural and well-log data

Skultéti

Tóth

2015

Acta Geod Geophys

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Quartz is among the most common minerals in the Earth's crust and is stable within a wide range of temperature and pressure conditions. As its microstructure is sensitive to different deformation mechanisms, quartz may present information about the structural evolution of many different rock types. The Szentl} orinc-1 well with its drill cuttings brought to the surface from approximately 2 km depth provides an exclusive chance to investigate the shear zone beneath. The drill cutting collection includes only a few small rock grains, and more than 80 % of the material consists of tiny (\1 mm) single quartz grains. In this study, three microstructurally extreme quartz grain types were separated during microscopic analysis: grains with undulose extinction (U), grains with subgrains (S), and grains with recrystallized grains (R). Moreover, numerous microstructurally transitional grains were measured, which represent combinations of the above extremes. The characterisation of single quartz grain microstructures along the whole well enables identification and localisation of the ductile shear zones inside the crystalline complex. This information was combined with well-log data, which could provide information about the brittle deformation. Using these logs, brittle shear zones can be localised along the well. When comparing depths and extensions of the deformed horizons, a coincidence of the brittle and ductile zones becomes clear. This behaviour may suggest two different evolution schemes: it could be caused by primarily evolved softened regions, or it could be described by a detachment fault model.

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“…GBS and its accommodation are usually envisioned to occur within the boundaries themselves and in adjacent, mantle-like regions of the grains [7,8]. Accordingly, the deformation rate associated with GBS increases as the grain size becomes finer.…”

Section: Introductionmentioning

confidence: 99%

Texture analysis of the transition from slip to grain boundary sliding in a discontinuously recrystallized superplastic aluminum alloy

et al. 2001

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Abstract-Texture and microtexture measurements were correlated with mechanical property data for a superplastic 5083 aluminum alloy. Prior processing had included an overaging treatment followed by severe rolling deformation and the as-received material was annealed prior to mechanical testing. Discontinuous recrystallization by particle-stimulated nucleation during the annealing accounts for a predominantly random texture, although a weak {100}Ͻ0vw> component was present, as well as a random grain boundary disorientation angle distribution. During elevated temperature deformation under dislocation-creep-controlled conditions, a distinct Ͻ111> fiber component and a relatively weak {100}Ͻ001> cube orientation, which are mutually compatible during uniaxial tensile extension, became apparent in the texture. Also, low-angle boundaries became evident in the disorientation distribution. In contrast, the random texture component and the randomness of the disorientation distribution became more evident when the material was deformed under conditions of grain boundary sliding control of deformation. A transition from dislocation creep to grain boundary sliding observed in the microtexture measurements of this work may be predicted by treating constitutive equations for dislocation creep and grain boundary sliding in an additive manner. Published by

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Grain-boundary sliding and its accommodation during creep and superplasticity

Cited by 648 publications

References 22 publications

The catalysis of mineral reactions by water and restrictions on the presence of aqueous fluid during metamorphism

The catalysis of mineral reactions by water and restrictions on the presence of aqueous fluid during metamorphism

Localisation of ductile and brittle shear zones along the Szentlőrinc-1 well in the Mecsekalja Zone using quartz microstructural and well-log data

Texture analysis of the transition from slip to grain boundary sliding in a discontinuously recrystallized superplastic aluminum alloy

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