Activation energy for superplastic deformation of an AlCu eutectic alloy
TL;DR: In this paper, the authors define a vitesse de deformation differentielle entre 440 and 540 C. La sensibilite a la vitez de deformations pendant la deformation superplastique est de 0,59, elle ne depend pas de maniere significative de la temperature.
About: This article is published in Scripta Metallurgica.The article was published on 1985-12-01. It has received 16 citations till now. The article focuses on the topics: Deformation (meteorology) & Superplasticity.
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TL;DR: In this article, the role of grain boundary phenomena towards enhancement of grain growth and cavitation, etc., is reviewed to understand the role that grain boundary processes play in the development of superplastic materials.
Abstract: Certain polycrystalline materials of fine equiaxed grains of size <10µm exhibit tensile ductility of several hundred to a few thousand per cent, called superplasticity, at intermediate strain rates and high temperatures. Experimental and theoretical results on mechanisms for superplastic deformation and concurrent microstructural evolution are reviewed to understand the role of grain boundary phenomena towards enhancement of grain growth and cavitation, etc. Grain boundary sliding (GBS) dominates superplastic flow, the extent of which varies between the grain and interphase boundaries in two-phase alloys. Accommodation to GBS is provided by diffusional and dislocation mechanisms, which are manifested in the form of grain boundary migration (GBM), grain rotation and grain switching events. Although GBS helps in retaining the initial equiaxed grain shape of superplastic materials, the accommodation processes accelerate grain growth. In the lack of other accommodation processes the cavities are formed, being more pronounced at the boundaries of maximum sliding. The ppm-level impurities present in superplastic materials do not influence the sliding and flow characteristics under typical superplastic conditions but they do promote cavitation and limit the ductility. The presence of precipitate or hard particles in quasi-single-phase superplastic materials inhibits GBM but provides sites for cavitation. Such materials exhibit more dislocation activities than anticipated for accommodation of GBS. The nature of microstructural changes noted during superplastic deformation supports the operation of cooperative GBS, in addition to a large variety of combinations between sliding and accommodation processes. Copyright © 2001 John Wiley & Sons, Ltd.
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TL;DR: In this paper, the diffusion coefficients of Al26 and Mn54 in aluminum have been determined between 450° and 650°C. The exact solution to Fick's second law for the appropriate boundary conditions was used in treating the data.
Abstract: Diffusion coefficients of Al26 and Mn54 in aluminum have been determined between 450° and 650°C. Low specific activities of the isotopes necessitated use of a thick layer technique. The exact solution to Fick's second law for the appropriate boundary conditions was used in treating the data. Temperature dependence of the diffusion coefficients may be expressed by the following equations: DAl26=1.71 exp−(34 000/RT)DMn54=0.22 exp−(28 800/RT).
413 citations
174 citations
TL;DR: The simultaneous diffusion of 64Cu and 67Cu has been measured in copper single crystals from 890 to 1061 °C and the strength of the isotope effect f ΔK is 0.684 ± 0.014 and is independent of temperature within the experimental error.
Abstract: The simultaneous diffusion of 64Cu and 67Cu has been measured in copper single crystals from 890 to 1061 °C. The strength of the isotope effect f ΔK is 0.684 ± 0.014 and is independent of temperature within the experimental error. This indicates that the contribution of divacancies to self-diffusion in copper is small. The diffusion coefficient of 67Cu in copper single crystals was measured from 700 to 1060 °C and is given by
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Die gleichzeitige Diffusion von 64Cu und 67Cu wurde im Bereich von 890 bis 1061 °C an Kupfereinkristallen gemessen. Die Grose des Isotopeneffekts f ΔK ergibt sich zu 0,684 ± 0,014 und ist temperaturunabhangig innerhalb der Mesgenauigkeit. Dies bedeutet, das der Beitrag von Doppelleerstellen zur Selbstdiffusion in Kupfer gering ist. Der Diffusionskoeffizient von 67Cu in Kupfereinkristallen wurde im Bereich von 700 bis 1060 °C gemessen und ergibt sich zu
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168 citations
TL;DR: In this article, the high temperature steady state deformation behavior of PbSn eutectic alloy was investigated over wide ranges of grain size (9.7 − 32.0 μm), temperature (298 − 443 K) and strain rate (10 −7 − 10 −2 s −1 ), after stability of microstructure and strength had been achieved through prior tensile deformation.
149 citations
105 citations