Creep Studies in Aluminium-2.25WT.% Magnesium.
89P
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| 格式: | Thesis |
| 语言: | 英语 |
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Obafemi Awolowo University
2023
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| 在线阅读: | https://ir.oauife.edu.ng/123456789/5629 |
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| _version_ | 1810764573325656064 |
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| author | Fagbulu, J. Babaniyi |
| author_facet | Fagbulu, J. Babaniyi |
| author_sort | Fagbulu, J. Babaniyi |
| collection | DSpace |
| description | 89P |
| format | Thesis |
| id | oai:ir.oauife.edu.ng:123456789-5629 |
| institution | My University |
| language | English |
| publishDate | 2023 |
| publisher | Obafemi Awolowo University |
| record_format | dspace |
| spelling | oai:ir.oauife.edu.ng:123456789-56292023-05-13T18:10:52Z Creep Studies in Aluminium-2.25WT.% Magnesium. Fagbulu, J. Babaniyi Elements Dislocation network model Burgers vector/ Annealed samples 89P In this project, a study of creep mechanism in an Al-2.25 wt % Mg alloy is conducted at temperatures between 573K and 623K and stresses (α ) ranging from 7.70 to 48.10 Mpa. Using the dislocation network model, the characteristics features of recovery-controlled and glidecontrolled creep mechanisms are delineated. One of the manifestations of the fundamental differences between these two mechanisms, it is demonstrated, is the disparity which should be observed between the experimentally observed obstacle strength parameter α exp in the equation σ = α exp Gb/p where G, b and p are the shear modulus, the Burgers vector of dislocations and the dislocation density respectively and the theoretically calculated value, αo. Specifically, the theoretical model predicts that α exp for glide creep should be greater than α exp for recovery creep. The conditions under which a transition from one creep mechanism to the other could occur in a given material are investigated (theoretically). It is demonstrated that for creep to be glidecontrolled, the dislocation glide velocity Vg must be related to the annihilation rate p a according to the expression Vg << β p a / (α1 p 3/2). Where α1 and β are constants. Otherwise, creep should be recovery-controlled. The implications of the theoretical model on the shape of creep curves for both mechanisms are discussed and are shown to be generally consistent with literature data. The creep tests performed on the Al-Mg alloy show that inverse transient creep curves are observed at low stresses and normal transients at high stresses. Also a change in transient creep curve shapes are observes when the annealed samples are prestrained prior to creep. Stress increase and stress removal tests performed (in the high stress range) during creep reveal certain creep characteristics which are trademarks of recovery-controlled creep at high stresses. Recovery tests performed on prestrained samples show that the flow stress decreases with recovery time, even though it never quite approaches the value characteristics of annealed samples 2023-05-13T18:03:07Z 2023-05-13T18:03:07Z 1985 Thesis Fagbulu, J.B (1983) Creep studies in aluminium-2.25WT.% magnesium. https://ir.oauife.edu.ng/123456789/5629 en application/pdf Obafemi Awolowo University |
| spellingShingle | Elements Dislocation network model Burgers vector/ Annealed samples Fagbulu, J. Babaniyi Creep Studies in Aluminium-2.25WT.% Magnesium. |
| title | Creep Studies in Aluminium-2.25WT.% Magnesium. |
| title_full | Creep Studies in Aluminium-2.25WT.% Magnesium. |
| title_fullStr | Creep Studies in Aluminium-2.25WT.% Magnesium. |
| title_full_unstemmed | Creep Studies in Aluminium-2.25WT.% Magnesium. |
| title_short | Creep Studies in Aluminium-2.25WT.% Magnesium. |
| title_sort | creep studies in aluminium 2 25wt magnesium |
| topic | Elements Dislocation network model Burgers vector/ Annealed samples |
| url | https://ir.oauife.edu.ng/123456789/5629 |
| work_keys_str_mv | AT fagbulujbabaniyi creepstudiesinaluminium225wtmagnesium |