The activation energies associated with superplastic flow
The activation energies associated with superplastic flow
A sigmoidal relationship was observed between strain rate and stress in the Zn-22% Al eutectoid alloy, dividing the behavior into three distinct regions. At high strain rates (region III), the activation energy was similar to that anticipated for lattice diffusion, and the results support the suggestion that the behavior in this region arises from an intragranular creep process. At intermediate strain rates (region II), the activation energy decreased to a value similar to that anticipated for grain boundary diffusion; whereas at very low strain rates (region I), the activation energy again increased to a value close to that for lattice diffusion. This trend was confirmed using two different modes of deformation (tensile and shear) and three different experimental procedures (strain rate cycling, stress cycling and a change in temperature technique). The results suggest that regions I and II arise through the sequential operation of two different processes.
1443-1450
Mohamed, Farghalli A.
0d8f02a9-fb40-4e5a-9222-3aecf3e4a460
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
December 1975
Mohamed, Farghalli A.
0d8f02a9-fb40-4e5a-9222-3aecf3e4a460
Langdon, Terence G.
86e69b4f-e16d-4830-bf8a-5a9c11f0de86
Mohamed, Farghalli A., Shei, Shen-Ann and Langdon, Terence G.
(1975)
The activation energies associated with superplastic flow.
Acta Metallurgica et Materialia, 23 (12), .
(doi:10.1016/0001-6160(75)90153-4).
Abstract
A sigmoidal relationship was observed between strain rate and stress in the Zn-22% Al eutectoid alloy, dividing the behavior into three distinct regions. At high strain rates (region III), the activation energy was similar to that anticipated for lattice diffusion, and the results support the suggestion that the behavior in this region arises from an intragranular creep process. At intermediate strain rates (region II), the activation energy decreased to a value similar to that anticipated for grain boundary diffusion; whereas at very low strain rates (region I), the activation energy again increased to a value close to that for lattice diffusion. This trend was confirmed using two different modes of deformation (tensile and shear) and three different experimental procedures (strain rate cycling, stress cycling and a change in temperature technique). The results suggest that regions I and II arise through the sequential operation of two different processes.
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Accepted/In Press date: 2 January 1975
Published date: December 1975
Identifiers
Local EPrints ID: 490642
URI: http://eprints.soton.ac.uk/id/eprint/490642
ISSN: 0956-7151
PURE UUID: 482466e7-8818-4c54-906a-a075534cf0f5
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Date deposited: 31 May 2024 16:51
Last modified: 01 Jun 2024 01:37
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Author:
Farghalli A. Mohamed
Author:
Shen-Ann Shei
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