Ionic mobility and superplasticity in ceramics

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dc.contributor.authorVilette, Anne L.en
dc.contributor.departmentMaterials Science and Engineeringen
dc.date.accessioned2014-03-14T21:40:47Zen
dc.date.adate2009-07-21en
dc.date.available2014-03-14T21:40:47Zen
dc.date.issued1994en
dc.date.rdate2009-07-21en
dc.date.sdate2009-07-21en
dc.description.abstractSuperplasticity and superionic conductivity (SIC), both thermally activated processes, have been independently observed in certain materials with a high diffusion coefficient in high temperature ranges. Intuitively, this observation leads one to the idea that both types of behavior may be inter-related with one another. Therefore, it is the purpose of this research to investigate, specifically, the deformation characteristics of two SIC's, Bi₂O₃ and YSZ (yttria-stabilized zirconia), and to attempt a correlation of their behavior. Compressive deformation of these two materials was conducted over a wide range of temperatures and at various strain rates in an effort to characterize the temperature and/or strain-rate dependences of any observed superplasticity. Steady-state flow stress values were utilized to calculate the strain-rate sensitivity, m, of the materials, as well as the activation energies (Q<sub>C</sub>) of superplasticity. Next, the obtained values of Q<sub>C</sub>. were compared to SIC activation energies from the literature. Bi₂O₃ exhibited structural superplasticity within the range of test conditions utilized. However, published values of SIC activation energy were lower than experimentally derived Q<sub>C</sub> by a factor of four. Therefore, one is not able to state whether or not there is any correlation between the two behaviors. Unfortunately, YSZ exhibited brittle behavior over the entire temperature and strain-rate ranges, so the same analysis could not be performed. Furthermore, SEM micrographs showed that YSZ samples, as processed, did not possess the proper microstructure required for superplasticity. Hence, no final conclusions on YSZ can be drawn from this study.en
dc.description.degreeMaster of Scienceen
dc.format.extentix, 87 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-07212009-040450en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-07212009-040450/en
dc.identifier.urihttp://hdl.handle.net/10919/43800en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1994.V554.pdfen
dc.relation.isformatofOCLC# 32457615en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1994.V554en
dc.subject.lcshCeramic materialsen
dc.subject.lcshIonic mobilityen
dc.subject.lcshSuperplasticityen
dc.titleIonic mobility and superplasticity in ceramicsen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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