2 edition of neighbor switching mechanism of superplastic deformation found in the catalog.
neighbor switching mechanism of superplastic deformation
David John Sherwood
Written in English
|Statement||by David John Sherwood.|
|The Physical Object|
|Pagination||xii, 460 leaves, bound :|
|Number of Pages||460|
Mechanisms of Superplastic Deformation of Nanocrystalline Silicon Carbide Ceramics 5a. CONTRACT NUMBER FA 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Yutaka Shinoda 5d. PROJECT NUMBER AH80 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Tokyo Institute of Author: Yutaka Shinoda. This paper shows that the same effects and consistent results can be obtained when deformation behavior is tested by stress relaxation method. The results support the conclusion that these features of superplastic deformation are due to intrinsic properties of superplastic material and not an artifact of the testing by: 1.
This proceedings volume, "Plastic Deformation of Ceramics," constitutes the papers of an international symposium held at Snowbird, Utah from August , It was attended by nearly scientists and engineers from more than a dozen countries representing academia, national laboratories, and industry. The authors used the concept of superplastic deformation to study the diffusion bonding of superplastic Al alloy Superplastic alloys attain large plastic elongation through grain-boundary sliding -- i.e., very fine internal grains slide and rotate, allowing neighboring grains to switch.
With scanning electron microscope (SEM), the surface morphology of phase boundary sliding (PBS) in superplastic deformation (SPD) of Zn-Al alloy and the diffusion behavior of Zn, Al interfaces in their powers’ sintering have been investigated. The results show that Zn-Al eutectoid microstructure can be achieved through their powders’ sintering, and the diffusion characteristic Cited by: 1. PHILOSOPHICAL MAGAZINE A, , VOL. 79, No. 2, Conditions for superplastic deformation By A. I. PSHENICHNYUK, 0. A. KAIBYSHEV and V. V. ASTANIN Institute for Metals Superplasticity Problems, Russian Academy of Sciences, Khaltur Ufa , Russia [Received 9 September ; accepted in revised form 25 March ABSTRACT.
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The purpose of the present work is to investigate superplastic deformation of PM-TiAl-based alloys at °C and °C with strain rates from 5 × 10 −5 s −1 to 1 × 10 −3 s −1.
In addition, high-temperature deformation mechanisms and superplastic deformation behaviors were also analyzed in detail at °C with 5 × 10 −5 s − by: 1.
It is widely accepted that grain boundary sliding (GBS) is the dominant superplastic deformation mechanism in fine-grained materials and is characterized by a stress exponent of ~2 . As shown in Figurefor the FSP Al alloys, a stress exponent of ~2 was observed in the strain rate range of 3×10 −3 –1×10 −1 s −1 at the investigated temperatures.
Under various conditions of stress and temperature various deformation mechanisms could be rate-controlling for superplastic deformation. In general at low At temperatures between approximately 40 and 65 pct of the absolute melting point grain boundary diffusion should be the dominant diffusion path while at higher temperatures volume diffusion should by: Figure Unit step of the deformation process in a neighbor switching mechanism.
A group of four grains moves from the initial, through the intermediate state to the final state. The initial and final states of the polycrystal are thermodynamically identical, although it has suffered a true strain ε 0 = In so doing, the grains suffer.
Initially plane-polished samples with surface markers were usually used to study the mechanisms of superplastic deformation.
Observations of the markers evolution at deformation found that GBS is a dominant mechanism of most superplastic materials. The contribution of GBS in the total strain is different for various by: The effective activation energy of superplastic deformation was calculated.
Contribution of grain boundary sliding was defined during superplastic deformation. Low value of grain boundary sliding, significant dynamic grain growth in stress direction, high dislocations activity and permanent continuous formation of sub-grain boundaries during Cited by: 2.
Deformation Mechanisms in Superplasticity. Annual Review of Materials Science Applications of Spinodal Alloys B Ditchek, and and L H Schwartz Annual Review of Materials Science Flow and Failure of Superplastic Materials D M R Taplin, G L Dunlop, and, and T G Langdon Annual Review of Materials Science.
by: Superplasticity is perhaps that reported by Pearson in of a Bi–Sn alloy that underwent nearly % elongation . He also claimed then, for the ﬁrst time, that grain-boundary sliding was the main deformation mechanism responsible for superplastic deformation.
The interest in Superplasticity has increased due to the. Critical review of mechanism of superplastic deformation in fine grained metallic materials.
Materials Science and Technology: Vol. 16, No.pp. Cited by: 7. Internal–stress superplastic materials can have a strain–rate sensitivity exponent as high as unity, i.e. they can exhibit Newtonian viscous behaviour. Superplastic forming is a specialist process used for deforming metal sheet to extremely large plastic strains to produce thin-walled components to the near-net shape.
Stretching of the sheet during superplastic forming is much higher than with rolling and sheet forming. Superplastic forming involves stretching the material at least % beyond its original size, although the deformation can.
The absence of voids results from solid-state diffusive mass transfer, locally enhanced crystal plastic deformation, or solution and precipitation of a grain boundary fluid. This mechanism operates at a low strain rate produced by neighbor switching. Grain boundary sliding is grain size and temperature.
Details of the grain neighbour switching process: (a) shear deformation switching with out-of-plane grain boundary sliding and (b) tensile deformation switching during emergence of interior by: Deformation mechanisms during superplastic forming Figure lists the deformation mechanisms during superplastic forming.
In principle, the same mechanisms are valid for both superplastic forming and classical creep of metals. These include grain boundary sliding and dislocation movement as wellFile Size: KB. The superplastic deformation of a hot-extruded GH billet was investigated by means of tensile tests with the strain rates of 10−4 s−1, 5 × 10−4 s−1 and 10−3 s−1 and at temperatures at °C, °C and °C.
The superplastic deformation of the GH alloy was reported here for the first : Shaomin Lv, Chonglin Jia, Xinbo He, Zhipeng Wan, Xinxu Li, Xuanhui Qu.
Abstract. The contributions of grain boundary sliding and intragranular dislocation slip in the AMg4 alloy (analog AA) during superplastic deformation have been analyzed by analyzing the deformation-induced changes in the sample surface having marker grids patterned by ion beam by: 4.
David John Sherwood. The Neighbor Switching Mechanism of Superplastic Deformation. Article. A mechanism for deformation-enhanced grain growth in single phase materials. neighbor switching. Numerical simulations based on these principles are discussed in the superplastic extensibility of the nano-crystalline copper originated from a deformation mechanism dominated by grain boundary activities rather than lattice dislocation.
after superplastic deformation typically exhibit high angle feature [4,r'ls. A core-mantle model for superplasticity not controlled by grain boundary sliding is proposed. It is suggested that crystal deformation in the mantle, in the vicinity of grain boundaries, is controlled by the annihilation of oppositely signed dislocations that climb together in the plane of the grain boundary and involve grain boundary diffusion.Most materials fracture with relatively little plastic deformation.
However, there is a class of materials, known as superplastic materials, that can undergo enormous deformation. The types of materials in which superplasticity is found now includes metals, metallic composites, intermetallics and : Paperback.Phenomena and mechanism on superplasticity of duplex stainless steels considered to be a controlling mechanism for superplastic deformation at °C.
grain neighbor switching .