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dc.contributor.advisorChristopher A. Schuh.en_US
dc.contributor.authorJohnson, Oliver Kenten_US
dc.contributor.otherMassachusetts Institute of Technology. Department of Materials Science and Engineering.en_US
dc.date.accessioned2015-09-17T19:08:55Z
dc.date.available2015-09-17T19:08:55Z
dc.date.copyright2015en_US
dc.date.issued2015en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/98740
dc.descriptionThesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.en_US
dc.descriptionCataloged from PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references (pages 117-133).en_US
dc.description.abstractGrain boundaries in polycrystals form a complex interconnected network of intercrystalline interfaces. The crystallographic character of individual grain boundaries and the network structure of the grain boundary ensemble have been experimentally observed to have a strong influence on many materials properties. This observation suggests that if we could control the types of grain boundaries present in a polycrystal and their spatial arrangement then it would be possible to dramatically improve the properties of polycrystalline materials and tailor them to specific engineering applications. However, there are a number of major obstacles that have, until now, precluded the realization of this opportunity: (1) methods capable of simultaneously quantifying the crystallographic and topological structure of grain boundary networks do not exist; (2) theoretical models relating grain boundary network structure to physical properties have not yet been developed; and, consequently, (3) there are no techniques to quantitatively identify grain boundary network structures that would be beneficial for a given property. In this thesis I address these obstacles by first developing a new statistical description of grain boundary network structure called the triple junction distribution function (TJDF), which encodes both crystallographic and topological information. I establish new results regarding the physical symmetries of triple junctions and find a relationship between crystallographic texture and grain boundary network structure. I then use the TJDF to develop a model for the effective diffusivity of a grain boundary network. Finally, using the relationship between texture and grain boundary network structure that I develop, I describe a method for texture-mediated grain boundary network design. This process permits the theoretical design of grain boundary networks with properties tailored to a given engineering application and is applicable to any polycrystalline material. I demonstrate the potential of this technique by application to a specific design problem involving competing design objectives for mechanical and kinetic materials properties. The result is a designed microstructure that is predicted to outperform an isotropic polycrystal by seven orders of magnitude.en_US
dc.description.statementofresponsibilityby Oliver Kent Johnson.en_US
dc.format.extent133 pagesen_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsM.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectMaterials Science and Engineering.en_US
dc.titleGrain boundary network designen_US
dc.typeThesisen_US
dc.description.degreePh. D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Materials Science and Engineering.en_US
dc.identifier.oclc920878150en_US


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