Show simple item record

dc.contributor.advisorMichael J. Demkowicz.en_US
dc.contributor.authorKashinath, Abisheken_US
dc.contributor.otherMassachusetts Institute of Technology. Department of Materials Science and Engineering.en_US
dc.date.accessioned2014-07-11T17:13:36Z
dc.date.available2014-07-11T17:13:36Z
dc.date.copyright2013en_US
dc.date.issued2013en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/88276
dc.descriptionThesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2013.en_US
dc.descriptionThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.en_US
dc.descriptionCataloged from student-submitted PDF version of thesis.en_US
dc.descriptionIncludes bibliographical references (pages 153-171).en_US
dc.description.abstractHe implanted into metals precipitates into nanoscale bubbles that grow into voids, degrading the properties of engineering alloys in nuclear energy applications. In this thesis, multi-scale modeling techniques and neutron reflectometry measurements are used to study the He trapping, clustering and growth of clusters at fcc-bcc interfaces. Choosing Cu-Nb as a model fcc-bcc interface, a predictive Cu-Nb-He interatomic potential is constructed using density functional theory. These calculations show that two-body radial forces are sucient to describe interactions of He with fcc Cu and bcc Nb. Atomistic simulations reveal that He is initially trapped in the form of stable, sub-nanometer platelet-shaped clusters and not bubbles at the Cu-Nb interface. This behavior occurs due to the spatial heterogeneity of interface energy: He wets high energy, heliophilic regions while avoiding low energy, heliophobic ones. Using these insights, the maximum He concentration that can be stored without forming bubbles at any interface in terms of its location-dependent energy distribution may be predicted. The modeling predictions are validated by neutron reflectometry measurements, which show that interfacial He bubbles form only above a critical He concentration and provide evidence for the presence of stable He platelets below a critical He concentration. This work paves the way for the design of composite structural materials with increased resistance to He-induced degradation by tailoring the types of interfaces they contain.en_US
dc.description.statementofresponsibilityby Abishek Kashinath.en_US
dc.format.extent171 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.titleHelium behavior at fcc-bcc semicoherent interfaces: trapping, clustering, nucleation, and growth of cavitiesen_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.oclc881179257en_US


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record