The role of deformation localization in superplastic flow

Astanin, V. V.; Kaĭbyshev, O. A.; Faizova, S. N.

doi:10.1016/0956-7151(94)90203-8

Cited by 43 publications

(9 citation statements)

References 6 publications

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“…At all examined strain rates the grain groups slide as an entity (Astanin et al, 1994;Zelin and Mukerjee, 1995;Zelin et al, 1994). Evidence of CGBS was revealed at all studied deformation conditions.…”

Section: Surface Microstructural Observationsmentioning

confidence: 81%

“…At the same time, the character of CGBS is not typical for conventional superplasticity (Astanin et al, 1994;Zelin and Mukerjee, 1995;Zelin et al, 1994). At the optimum strain rate of superplasti deformation the secondary system of CGBS begins to act only after large strain.…”

Section: Discussion Operating Deformation Mechanismsmentioning

confidence: 99%

“…The aim of this paper is to report experimental results concerning microstructural and texture changes of the composite PM 2014-20% A1203 during superplastic deformation and to discuss the operative deformation mechanism in the light of the concept of CGBS (Astanin et al, 1994;Zelin et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

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Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al₂O₃

Кайбышев

Kazyhanov

1999

Texture, Stress, and Microstructure

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The effects of superplastic deformation (SPD) on grain structure and texture evolution of the A1 2014-20%A1203 composite produced via powder metallurgical method were investigated in conjunction with surface relief observations. Samples were deformed in tension at different strains in the range of true strain rates 10-4-10 -1 at temperature 500C. It was found that SPD strains have a large effect on both texture and grain size. At the initial stage of superplastic flow, deformation bands are formed in the aluminum matrix along the tension direction. Simultaneously, the initial (1 1) fiber texture is broken and formation of (1 10) fiber texture takes place. Further strain up to 50% leads to grain structure change from banded structure to nearly equiaxed. The (1 1) fiber texture is restored and texture intensity decreases with increasing strain. Strain rate dependence of texture developments showed evidence for dislocation activity in examined strain range. The relation between microstructure evolution and texture development during superplastic deformation of the PM 2014-20% A1203 composite is explained from the viewpoint of cooperative grain boundary sliding (CGBS).

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Section: Surface Microstructural Observationsmentioning

confidence: 81%

Section: Discussion Operating Deformation Mechanismsmentioning

confidence: 99%

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Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al₂O₃

Кайбышев

Kazyhanov

1999

Texture, Stress, and Microstructure

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“…First, the plastic flow is nonuniform. As a rule, it localizes in the form of deformation bands (Ref [27][28][29]. The nonhomogeneous flow can lead to a nonhomogeneous interaction at the fiber-matrix interface and a considerable decrease in composite strength.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of metal-matrix composites by application of the superplasticity effect

Astanin

Kaĭbyshev

Imayeva

et al. 1997

J. of Materi Eng and Perform

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The production of continuous-fiber metal-matrix composites (MMCs) with improved mechanical properties by solid-state consolidation under superplastic conditions was investigated. The finite-element method was used to model MMC consolidation, which was experimentally studied on a sample of boronaluminum composite. It was shown that the deformation properties of a matrix exert considerable influence on metal flow geometry and its strain-stress state. The superplasticity effect provides the straightening of a matrix now front and the localization of an intense deformation zone. It also facilitates the removal of pores in the final stage of hardening and considerably decreases local stresses on the fiber surface. The features of matrix material flow during consolidation of composites were considered. It was shown that the matrix deformation during composite consolidation takes place in the form of cooperative grain-boundary sliding and intragranular sliding. The mechanism of matrix deformation determines a type of fiber-matrix reaction at the interface, or, alternatively, the type of fiber-matrix interface interaction depends on the intensity of localized deformation in the given area. Identification of the interface structure was performed by acoustic emission.

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“…Sin embargo, si se aplica una tensión uniaxial, la energía para la difusión puede ser menor en la dirección de máximo esfuerzo cortante, en consecuencia grupos de granos probablemente se moverán en conjunto a lo largo de bordes de grano cuya orientación sea muy próxima a la dirección de máximo corte, lo que dará origen a orientación preferencial de granos en relación con el eje de esfuerzo macroscópico. En la región plástica estas orientaciones preferenciales producirán bandas de deformación localizadas como las observadas por ASTANIN et al [18,19]. El efecto del flujo de difusión disipará parte de la energía elástica almacenada en el sólido, lo cual en la escala macroscópica aparecerá como un máximo en la fricción interna del material también llamada tan δ.…”

Section: Figuraunclassified

Caracterización de tres aleaciones superplásticas utilizando análisis mecánico dinámico (DMA)

2008

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RESUMENEl Análisis Mecánico Dinámico (DMA) es un método que tradicionalmente se utiliza para el análisis de polímeros. Está técnica es muy sensible a cambios en las propiedades de los materiales, como la transición vítrea en polímeros. Se puede utilizar para evaluar el ángulo de desfasamiento (tan δ), el módulo de almacenamiento (E') el módulo de pérdida (E") y recientemente las temperaturas de transformación en aleaciones metálicas.Se utilizó DMA para estudiar tres diferentes aleaciones: Zn-21%Al-2%Cu; Cd-17%Zn y Sn-38%Pb, cada una en condición superplástica y no superplástica. Los resultados mostraron la presencia de un pico en la curva de módulo de pérdida el cual se puede relacionar con la temperatura superplástica para cada una de las aleaciones analizadas. Es posible que el incremento en el módulo de pérdida se relacione con procesos de reacomodamiento de bordes de grano desde un estado de no-deslizamiento hacia un estado de deslizamiento. La activación de un gran número de bordes de grano puede relacionarse con la disminución en el esfuerzo cortante requerido para vencer la energía de cohesión entre granos cuando el material se encuentra en la temperatura superplástica.Palabras clave: Análisis Mecánico Dinámico, superplasticidad, temperatura homóloga. Characterization of three superplastic alloys using dynamic mechanic analysis ABSTRACTDynamic Mechanical Analysis (DMA) is traditionally a standard method in polymer analysis. This technique is very sensitive to changes in materials properties, like glass transition in polymers. It can be used to measure phase difference (tan δ), storage modulus (E'), loss modulus (E") and recently transformation temperatures for metal alloys.Three different alloys: Zn-21%Al-2%Cu, Cd-17%Zn and Sn-38%Pb, each one in a superplastic and non-superplastic condition have been studied using Dynamic Mechanical Analysis (DMA). Results showed a clear peak of the loss modulus which is related to the superplastic temperature for each analyzed alloy. It is possible that the increase of the loss modulus is related with the accommodation of grain boundaries from non-sliding state to sliding state. The activation of a higher number of grain boundaries can be connected with a lower shear stress required to overcome the cohesion energy between grains at the superplastic temperature.

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The role of deformation localization in superplastic flow

Cited by 43 publications

References 6 publications

Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al₂O₃

Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al₂O₃

Fabrication of metal-matrix composites by application of the superplasticity effect

Caracterización de tres aleaciones superplásticas utilizando análisis mecánico dinámico (DMA)

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The role of deformation localization in superplastic flow

Cited by 43 publications

References 6 publications

Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al2O3

Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al2O3

Fabrication of metal-matrix composites by application of the superplasticity effect

Caracterización de tres aleaciones superplásticas utilizando análisis mecánico dinámico (DMA)

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Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al₂O₃

Texture and Microstructure Evolution During Superplasticity of theMetal Matrix Composite PM 2014 Al–20% Al₂O₃