Quantitative texture studies of the superplastically deformed AlCu eutectic alloy
TL;DR: In this article, the texture changes can be interpreted in terms of grain boundary sliding, dislocation motion and diffusion creep in the Al-33 wt% Cu eectic alloy.
About: This article is published in Acta Metallurgica.The article was published on 1974-05-01. It has received 55 citations till now. The article focuses on the topics: Grain Boundary Sliding & Diffusion creep.
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273 citations
TL;DR: In this paper, the creep behavior of the superplastic Pb-62% Sn eutectic was investigated for grain sizes from 5·8 to 14·5 μm and at temperatures in the range from 336 to 422 K. The results showed a sigmoidal relationship between strain rate and stress.
Abstract: The creep behaviour of the superplastic Pb-62% Sn eutectic was investigated for grain sizes from 5·8 to 14·5 μm and at temperatures in the range from 336 to 422 K. The results showed a sigmoidal relationship between strain rate and stress. At intermediate strain rates (∼ 10−5–10−2 sec−1), the stress exponent was ∼1·65, the exponent of the inverse grain size was ∼2·3, and the activation energy was similar to the value anticipated for grain boundary diffusion. At very low strain rates (≲10−5 sec−1), the stress exponent was ∼3·0, the exponent of the inverse grain size was ∼2·3, and the activation energy was similar to the value anticipated for lattice self-diffusion. The results are not entirely consistent with either of the two major theories of superplasticity, but suggest instead the sequential operation of two different deformation processes.
150 citations
TL;DR: The microstructural aspects of the superplastic phenomenon are reviewed in this article, where experimental results of a very large number of investigations are critically analysed in the context of: grain shape and size; grain growth; grain boundary sliding and migration, grain rotation and rearrangement; diffusion and dislocation activity.
Abstract: The microstructural aspects of the superplastic phenomenon are reviewed. The experimental results of a very large number of investigations are critically analysed in the context of: grain shape and size; grain growth; grain boundary sliding and migration, grain rotation and rearrangement; diffusion and dislocation activity. It is shown, that in spite of often conflicting evidence in the literature, a common pattern of microstructural behaviour emerges for all the materials and conditions investigated to date.
124 citations
TL;DR: In this paper, the relative motion of grains during superplastic flow of an Al-9.3Zn-1.03Mg-0.22 wt.%Zr alloy has been examined by the translation of reference markers in the surface and interior of specimens.
Abstract: The topological feature of the relative motion of grains during superplastic flow of an Al-9.3Zn-1.03Mg-0.22 wt.%Zr alloy has been examined by the translation of reference markers in the surface and interior of specimens. Microstructural evidence was obtained for grain-switching events based on the relative motion of a group of four grains. The translation of the grains seemed to occur by sliding and rotation. On the basis of the results of a texture study, accommodation strains required in this process are attributed predominantly to slip. Hence, the role played by slip in deformation at maximum strain-rate sensitivity is particularly significant for this alloy.
93 citations
TL;DR: In this article, synthetic anorthite aggregates were deformed in a Paterson gas deformation apparatus at confining pressures up to 400 MPa in torsion and axial compression at temperatures between 950 and 1200 °C.
71 citations
Cites background or methods from "Quantitative texture studies of the..."
...This conclusion is based on experiments on metals (Cutler et al., 1974; McDarmaid et al., 1985; Bowen et al., 1991; Padmanabhan et al., 1991; Fan and Chaturvedi, 2000; Engler et al., 2000; Pérez-Prado et al., 2001), calcite (Schmid et al., 1977), olivine (Fliervoet et al., 1999) and perovskite…...
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...It is generally accepted that GBS creep involving grain rotation progressively removes the texture of the aggregate (Cutler et al., 1974; McDarmaid et al., 1985; Bowen et al., 1991; Padmanabhan et al., 1991; Chokshi et al., 1993; Fan and Chaturvedi, 2000; Engler et al., 2000; Pérez-Prado et al., 2001; del Valle and Ruano, 2007)....
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...This conclusion is based on experiments on metals (Cutler et al., 1974; McDarmaid et al., 1985; Bowen et al., 1991; Padmanabhan et al., 1991; Fan and Chaturvedi, 2000; Engler et al., 2000; Pérez-Prado et al., 2001), calcite (Schmid et al....
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...…important to note that a large number of studies based on texture analysis support the idea that dislocation glide operates as a direct response to the applied stress, as well as being an accommodation process for GBS (Cutler et al., 1974; Kassner and Pérez-Prado, 2000; Pérez-Prado et al., 2001)....
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...It is generally accepted that GBS creep involving grain rotation progressively removes the texture of the aggregate (Cutler et al., 1974; McDarmaid et al., 1985; Bowen et al., 1991; Padmanabhan et al., 1991; Chokshi et al., 1993; Fan and Chaturvedi, 2000; Engler et al., 2000; Pérez-Prado et al.,…...
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References
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TL;DR: In this article, the authors discussed the mechanism of creep in polycrystalline alumina based on the differences between the lattice and boundary diffusion models and showed that the boundary diffusion model is more stable than lattice diffusion model, while the grain size dependence and the numerical constant are greater.
Abstract: The creep rate (ė) predicted by the boundary diffusion (Db) model is ė≃150σDbWΩ/(GS)3kT, where σ is the stress, W is the boundary width, (GS) is the average grain size, and Ω is vacancy volume. The stress dependence is the same as the lattice diffusion model, given by C. Herring, while the grain size dependence and the numerical constant are greater for boundary diffusion. Discussion of the mechanism of creep in polycrystalline alumina is based on the differences between the lattice and boundary diffusion models.
2,050 citations
01 May 1970-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, a phenomenological description of crystallographic slip and pencil glide in single crystals is outlined, with emphasis on the behavior under prescribed strains Theoretical relations are established between these single-crystal properties and the behavior of quasi-homogeneous, quasi-isotropic polycrystals deforming uniformly on a macroscopic scale, at subdiffusive temperatures.
Abstract: A phenomenological description of crystallographic slip and pencil glide in single crystals is outlined, with emphasis on the behavior under prescribed strains Theoretical relations are established between these single-crystal properties and the behavior of quasi-homogeneous, quasi-isotropic polycrystals deforming uniformly on a macroscopic scale, at subdiffusive temperatures Experimental comparisons between single crystals and polycrystals are reviewed, considering flow stress, work hardening, temperature and strain rate effects, and various effects of grain size
800 citations
TL;DR: In this article, the orientation distribution of crystallites in anisotropic polycrystalline samples can be derived from a set of plane-normal distributions obtained by x-ray diffraction measurements.
Abstract: A method is presented here by which orientation distribution of crystallites in anisotropic polycrystalline samples can be derived from a set of plane‐normal distributions obtained by x‐ray diffraction measurements. It is the generalization of the similar procedure proposed previously for analysis of samples having fiber texture. It thus represents a completely general solution to the problem of pole figure inversion, applicable to samples having any arbitrary symmetry elements. The plane‐normal distribution function is expanded in a series of spherical harmonics, the coefficients of which, Qlmi, can be determined by numerical integration of experimental diffraction data. The crystallite distribution function is expanded in a series of generalized spherical harmonics which appear as solutions to the Schrodinger wave equation of a symmetric top. The coefficients of the crystallite distribution function, Wlmn, are then obtained as linear combinations of Qlmi. Symmetry properties of Wlmn arising from crystallographic or statistical symmetry elements existing in the sample are examined. The methods of estimating the series truncation errors and of minimizing the experimental error by a least‐squares method, previously proposed in connection with fiber texture analysis, are still applicable here with appropriate generalizations. In addition it is shown that the effect of diffraction line broadening due to finite size or imperfection of crystallites can also be allowed for at least approximately.
757 citations
TL;DR: In this article, the grain boundary allotriomorphs were measured in the temperature range 200°-325°C in an Al-4 % Cu alloy, and it was found that both the lengthening and thickening rates were orders of magnitude too rapid to be controlled by the volume diffusion of Cu toward the growing allotrimorphs.
198 citations