Mechanical properties and microstructural characteristics of an Al-Mg alloy with bimodal grain size at room and elevated temperatures

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dc.contributor Jordon, J. Brian
dc.contributor Thompson, Gregory B.
dc.contributor Weaver, Mark Lovell
dc.contributor Woodbury, Keith A.
dc.contributor.advisor Ladani, Leila J. Magee, Andrew 2017-03-01T16:34:50Z 2017-03-01T16:34:50Z 2012
dc.identifier.other u0015_0000001_0001045
dc.identifier.other Magee_alatus_0004M_11200
dc.description Electronic Thesis or Dissertation
dc.description.abstract The strength of aluminum alloy 5083 has been shown to be significantly improved when it is engineered to have a bimodal grain size consisting of coarse grains (CGs) embedded in an ultrafine grained (UFG) matrix. This study investigates how a variety of parameters including strain rate, temperature, specimen thickness, CG ratio, and anisotropy affect the mechanical properties of this material when tested in uniaxial tension. The material is fabricated through cryomilling, cold isostatic pressing, and extrusion. A full factorial experiment is designed and implemented to test these effects on the material. Post-test examination of the specimens with optical and electron microscopes is conducted in order to gain a deeper understanding of the material's fracture behavior. While the material shows greatly improved strength compared to conventional Al-Mg alloys at room temperature, its strength rapidly decreases with rising temperature such that by 473 K, it was observed to be weaker than conventional Al 5083 at the same temperature. Dynamic recovery was observed in high temperature tests and the amount of recovery was found to depend on the material's CG ratio. Strain rate sensitivity was observed in the material at all temperatures. Significant differences were observed both in the material's properties and its fracture surface when the specimens were loaded parallel or perpendicular to the extrusion direction. A constitutive model based on Joshi's model of plasticity was developed to describe the material's room temperature behavior.
dc.format.extent 75 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Mechanical engineering
dc.title Mechanical properties and microstructural characteristics of an Al-Mg alloy with bimodal grain size at room and elevated temperatures
dc.type thesis
dc.type text University of Alabama. Dept. of Mechanical Engineering Mechanical Engineering The University of Alabama master's M.S.

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