Deformation Mechanisms of Nanostructured Thermoelectric Alloys

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dc.contributor.advisorSharma, Pradeep
dc.contributor.committeeMemberWhite, Kenneth W.
dc.contributor.committeeMemberKulkarni, Yashashree
dc.contributor.committeeMemberThilly, Ludovic L.
dc.contributor.committeeMemberTromas, Christophe
dc.contributor.committeeMemberVajtai, Robert
dc.contributor.committeeMemberDemkowicz, Michael J.
dc.contributor.committeeMemberRobertson, Andrew
dc.creatorAumand, Matthieu Simon Maxime
dc.date.accessioned2019-09-10T13:51:44Z
dc.date.createdDecember 2018
dc.date.issued2018-12
dc.date.submittedDecember 2018
dc.date.updated2019-09-10T13:51:45Z
dc.description.abstractIncreasing the figure of merit ZT of thermoelectric (TE) alloys is a challenge that is currently attempted through various metallurgy methods, including nanostructuring and dislocation engineering. Microstructures with such level of complexity raises questions about the mechanical reliability of these new materials. Indeed, despite the values of hardness and elastic modulus known for the clear majority of TE materials, the data on deformation mechanisms are still rare. Focusing on the nanostructured p-type half-Heusler Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, our multi-scale study aims to analyze the deformation mechanisms. Experiments conducted at macro-, meso- and micro-scale are designed to trigger and assess plasticity mechanisms. Compression testing on bulk samples subject to a confining pressure environment and temperature leads to an exclusive brittle failure. The mixed-mode failure mechanisms involve switching between intra- and inter-granular crack propagation, depending on the grain size met by the crack tip. Indentation toughness at meso-scale generates cracks, while TEM analysis of the crack tip area confirms no dislocation activity and 3D-EBSD technique confirms the mixed crack propagation behavior. At micro-scale, micro-pillar compression stress-strain curves and failure mechanisms are comparable with bulk samples testing analysis. These results can be used to provide design guidelines for more crack-resistant TE alloys.
dc.description.departmentMechanical Engineering, Department of
dc.format.digitalOriginborn digital
dc.format.mimetypeapplication/pdf
dc.identifier.urihttps://hdl.handle.net/10657/4388
dc.language.isoeng
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectThermoelectrics
dc.subjectMechanical properties
dc.subjectHalf-Heusler
dc.subjectDislocations
dc.subjectDeformations
dc.subjectFracture behavior
dc.titleDeformation Mechanisms of Nanostructured Thermoelectric Alloys
dc.type.dcmiText
dc.type.genreThesis
local.embargo.lift2020-12-01
local.embargo.terms2020-12-01
thesis.degree.collegeCullen College of Engineering
thesis.degree.departmentMechanical Engineering, Department of
thesis.degree.disciplineMaterials Engineering
thesis.degree.grantorUniversity of Houston
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy

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