Fundamentals of Superplasticity and Its Application

Sherby, O. D.; Caligiuri, R.; Kayalı, E. Sabri; White, Richard Allen

doi:10.1007/978-1-4615-8300-4_7

Cited by 17 publications

(12 citation statements)

References 30 publications

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“…Superplasticity was found in sintered polycrystalline ceramic materials, but it is mainly caused by the deformation of amorphous intergrain boundary layers. [1][2][3] Blistering on materials surface is another example of large plastic deformation occurring in the above non-ductile materials. We developed 'grazing incidence electron microscopy' (GIEM) for non-destructive structural analysis of surface protrusions, 4) and we have applied this method to observation of the surface blistering phenomena in covalent bonded nonductile materials.…”

Section: Introductionmentioning

confidence: 99%

Cross Sectional TEM Observation of Gas-Ion-Irradiation Induced Surface Blisters and Their Precursors in SiC

2003

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Cross sectional structures of surface blisters and their precursors in SiC formed by H þ , D þ and He þ irradiation were examined with transmission electron microscopy and electron energy-loss spectroscopy. The substructures of the H þ -and D þ -irradiated samples showed similar features, and experimental results suggested that H 2 and CH 4 bubbles nucleated after H(D)-trapping sites were saturated and the first nucleated bubbles grew by absorbing the gas molecules formed by further ion irradiation, followed by lift-up of the surface layer with increasing the internal pressure. The implanted hydrogen atoms other than those forming bubbles were scattered in atomic form, preferably bonded to carbon atoms. On the other hand the substructure of He þ irradiated sample was very similar to that of metals and other materials irradiated by He þ , and it is considered that the formation mechanism of He-blister is common for most materials.

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Section: Introductionmentioning

confidence: 99%

Cross Sectional TEM Observation of Gas-Ion-Irradiation Induced Surface Blisters and Their Precursors in SiC

2003

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“…3,[11][12][13][14][15] Very recently, it has been pointed out that the model can explain superplastic behavior not only in metallic materials but also in alumina. 17) Therefore, the deformation model considered here is based on the concept that GBS is the predominant mode of deformation and that sliding is accommodated by slip which is controlled by dislocation climb.…”

Section: Deformation Modelmentioning

confidence: 99%

“…The term x has been roughly estimated to be 1 Â 10 À2 for superplastic flow. 11,12,17) This equation indicates that the two diffusional paths are independent, and both grain boundary diffusion and lattice diffusion contribute simultaneously in the ratecontrolling process. The term x in equation (10) is usually considered to be unity in diffusional creep mechanisms.…”

Section: Phenomenological Relationmentioning

confidence: 99%

“…The term x in equation (10) is usually considered to be unity in diffusional creep mechanisms. 11,12) The difference in x-value between diffusional creep and superplasticity indicates that the normal models for grain boundary diffusion must be inappropriate under the occurrence of extensive GBS. 12) Recently, the effective diffusivity was precisely determined using relatively coarse-grained superplastic magnesium alloys.…”

Section: Phenomenological Relationmentioning

confidence: 99%

“…[7][8][9][10] Recent research has shown that the slip accommodation mechanism would be adequate to describe conventional superplastic flow. 3,[11][12][13][14][15] The proposed theoretical constitutive equations for diffusion-and slip-accommodated GBS are listed in Table 1. [6][7][8][9][10] All of these models have some features that are in agreement with experimental observations.…”

Section: Introductionmentioning

confidence: 99%

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Deformation Mechanism of Fine-Grained Superplasticity in Metallic Materials Expected from the Phenomenological Constitutive Equation

2004

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The superplastic behavior of fine-grained metals is well described by the deformation model in which grain boundary sliding (GBS) is accommodated by slip. This slip accommodation process involves the sequential steps of glide and climb, with climb assumed to be the ratecontrolling process. The climb distance during GBS is often considered to be on the order of grain size in the conventional theoretical models. However, these models have not been able to predict quantitatively the strain rates actually observed in fine-grained superplastic materials. Therefore, the deformation model was reviewed by comparing the theoretical and phenomenological equations in order to accurately understand the mechanism of the accommodation process. The analyses revealed that the climb process is governed by the effective diffusivity. The climb distance through the grain boundary is of the order of the grain size, and that through the lattice close to the dislocation core size was quantitatively in agreement with the phenomenological relation.

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Enhanced densification of white cast iron powders by cyclic phase transformations under stress

Ruano¹,

Wadsworth

Sherby

1982

Metall Trans A

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Fundamentals of Superplasticity and Its Application

Cited by 17 publications

References 30 publications

Cross Sectional TEM Observation of Gas-Ion-Irradiation Induced Surface Blisters and Their Precursors in SiC

Cross Sectional TEM Observation of Gas-Ion-Irradiation Induced Surface Blisters and Their Precursors in SiC

Deformation Mechanism of Fine-Grained Superplasticity in Metallic Materials Expected from the Phenomenological Constitutive Equation

Enhanced densification of white cast iron powders by cyclic phase transformations under stress

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