On the creep transition from superplastic behavior to nanocrystalline behavior

Mohamed, Farghalli A.

doi:10.1016/j.msea.2015.11.095

Cited by 6 publications

(5 citation statements)

References 21 publications

(21 reference statements)

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“…A number of empirical models for GBS have been formulated for fine-grained materials, but no basic model seems to be available (for a review, see [26]). In agreement with experiments, these models suggest a stress exponent of 2 and a creep rate that is inversely proportional to the square of the grain size for micro-grained materials [26,27]. This dependence is also frequently observed for superplastic alloys.…”

Section: Introductionsupporting

confidence: 83%

Basic creep modelling of aluminium

Spigarelli

Sandström

2018

Materials Science and Engineering: A

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Section: Introductionsupporting

confidence: 83%

Basic creep modelling of aluminium

Spigarelli

Sandström

2018

Materials Science and Engineering: A

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“…a) Dislocation accommodated boundary sliding without a pileup of dislocations . b) Dislocation accommodated boundary sliding with a pileup of dislocations …”

Section: Discussionmentioning

confidence: 99%

“…Under this condition, the equilibrium distance between two edge dislocations, L , is given by

\frac{L}{b} = (\frac{G}{τ}) / [2 π (1 - ν)]

where is Poisson's ratio, ν (=1/3). By substituting for, Equation (a) becomes

\frac{L}{b} = 0.25 (\frac{G}{τ})

…”

Section: Discussionmentioning

confidence: 99%

“…a) Dislocation accommodated boundary sliding without a pileup of dislocations. [82,153] b) Dislocation accommodated boundary sliding with a pileup of dislocations. [131,153] www.advancedsciencenews.com www.aem-journal.com associated with superplasticity during deformation in region II (the superplastic region) is produced by grain-boundary sliding while strain during creep is generated by dislocation multiplication and movement in the interiors of the grains (in case of diffusional creep, strain is produced by vacancies, rather than dislocations).…”

Section: Superplasticity Versus Creepmentioning

confidence: 99%

“…[82,153] b) Dislocation accommodated boundary sliding with a pileup of dislocations. [131,153] www.advancedsciencenews.com www.aem-journal.com associated with superplasticity during deformation in region II (the superplastic region) is produced by grain-boundary sliding while strain during creep is generated by dislocation multiplication and movement in the interiors of the grains (in case of diffusional creep, strain is produced by vacancies, rather than dislocations). In case of superplasticity, dislocations, Nabarro-Herring creep, Coble creep, or the formation of cavities may serve as an accommodation process for boundary sliding.…”

Section: Superplasticity Versus Creepmentioning

confidence: 99%

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Creep and Superplasticity: Evolution and Rationalization

Mohamed

2020

Adv Eng Mater

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Detailed studies on the creep behavior of materials are of scientific and practical significance. From a scientific point of view, data obtained from such studies are critical to the characterization of creep behavior in terms of deformation mechanisms. From a practical point of view, information inferred from such studies is useful because of its relevance to many design considerations. Over the past several decades, much progress has been made in rationalizing the creep behavior of metals and solid‐solution alloys. Such progress is extended to understanding the creep behavior of new classes of materials such as powder metallurgy (PM) Al alloys, discontinuous SiC composites, superplastic alloys, and high‐entropy alloys (HEAs). Progress in micrograin superplasticity (1 μm < d < 10 μm, where d is the grain size) has been applied to the emergence of high strain rate (HSR) superplasticity using ultrafine‐grained alloys (0.3 μm < d < 1 μm). The concept of creep is utilized to develop a deformation mechanism for nanocrystalline (nc) materials (d < 100 nm). Using the details of this mechanism, it is possible (1) to explain why the behavior of nc material is not superplastic and 2) to predict a transition from superplastic behavior to nc behavior.

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