{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/95309"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/95309","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Disorder and nanopatterning in ordered binary alloys: in situ ion irradiation and kinetic Monte Carlo simulation","abstract":"We study the effects of temperature and disordering rate on the ordered microstructures of real and simulated binary alloys. The behavior of Cu3Au, an alloy with L12 chemical order, is investigated experimentally through in situ electron diffraction and dark-field transmission electron microscopy. Under irradiation with 500 keV Ne+ ions, our diffraction analysis reveals a similar, but steeper, trend in disordering rate as previously reported by resistivity. Further investigations by superlattice, dark-field imaging lead to the discovery of temperature and dose rate dependent alterations to the ordered microstructure of the alloy. The process appears to be driven by the nucleation of small, highly ordered domains within the existing microstructure. We attempt to simulate these and other disordering behaviors through a kinetic Monte Carlo method. For simplicity, we focus these investigations on two-dimensional, ordered AB alloys featuring various first and second neighbor ordering energies. Disorder is imposed in these simulated alloys through manipulation of vacancy-atom exchange rates and forced atomic replacement. For certain disordering-temperature conditions and ordering energies 𝐽2/𝐽1≲0.5, a previously unreported patterning of order is observed, dividing the ordered microstructure into competing, highly ordered domains. This behavior is rationalized in terms of decreased anti-phase boundary energies at the given ordering energies, and a physical picture of the patterning reaction is presented. The application of this picture to Cu3Au is deemed plausible and future work proposed.","abstract_html":"We study the effects of temperature and disordering rate on the ordered microstructures of real and simulated binary alloys. The behavior of Cu3Au, an alloy with L12 chemical order, is investigated experimentally through in situ electron diffraction and dark-field transmission electron microscopy. Under irradiation with 500 keV Ne+ ions, our diffraction analysis reveals a similar, but steeper, trend in disordering rate as previously reported by resistivity. Further investigations by superlattice, dark-field imaging lead to the discovery of temperature and dose rate dependent alterations to the ordered microstructure of the alloy. The process appears to be driven by the nucleation of small, highly ordered domains within the existing microstructure. We attempt to simulate these and other disordering behaviors through a kinetic Monte Carlo method. For simplicity, we focus these investigations on two-dimensional, ordered AB alloys featuring various first and second neighbor ordering energies. Disorder is imposed in these simulated alloys through manipulation of vacancy-atom exchange rates and forced atomic replacement. For certain disordering-temperature conditions and ordering energies 𝐽2/𝐽1≲0.5, a previously unreported patterning of order is observed, dividing the ordered microstructure into competing, highly ordered domains. This behavior is rationalized in terms of decreased anti-phase boundary energies at the given ordering energies, and a physical picture of the patterning reaction is presented. The application of this picture to Cu3Au is deemed plausible and future work proposed.","abstract_has_math":false,"creators":["Lear, Calvin R"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Materials Science & Engr","degree_department":null,"school":null,"contributors":["Bellon, Pascal","Averback, Robert S.","Zuo, Jian-Min","Maass, Robert","Zhang, Yang"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017-03-01T15:48:30Z","date_published":"2017-03-01T15:48:30Z","updated_at":"2026-07-22T22:26:37Z","subjects":["chemical order","chemical disorder","patterning","ion irradiation","in situ","transmission electron microscopy","kinetic Monte Carlo","atomistic simulation"],"languages":["en"],"rights":["Copyright 2016 Calvin Lear"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/95309","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Bellon, Pascal","Averback, Robert S.","Zuo, Jian-Min","Maass, Robert","Zhang, Yang"]},{"key":"dc:creator","label":"Author","values":["Lear, Calvin R"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2017-03-01T15:48:30Z","2016-11-11","2016-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science & Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["chemical order","chemical disorder","patterning","ion irradiation","in situ","transmission electron microscopy","kinetic Monte Carlo","atomistic simulation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2016 Calvin Lear"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/95309"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["We study the effects of temperature and disordering rate on the ordered microstructures of real and simulated binary alloys. The behavior of Cu3Au, an alloy with L12 chemical order, is investigated experimentally through in situ electron diffraction and dark-field transmission electron microscopy. Under irradiation with 500 keV Ne+ ions, our diffraction analysis reveals a similar, but steeper, trend in disordering rate as previously reported by resistivity. Further investigations by superlattice, dark-field imaging lead to the discovery of temperature and dose rate dependent alterations to the ordered microstructure of the alloy. The process appears to be driven by the nucleation of small, highly ordered domains within the existing microstructure. We attempt to simulate these and other disordering behaviors through a kinetic Monte Carlo method. For simplicity, we focus these investigations on two-dimensional, ordered AB alloys featuring various first and second neighbor ordering energies. Disorder is imposed in these simulated alloys through manipulation of vacancy-atom exchange rates and forced atomic replacement. For certain disordering-temperature conditions and ordering energies 𝐽2/𝐽1≲0.5, a previously unreported patterning of order is observed, dividing the ordered microstructure into competing, highly ordered domains. This behavior is rationalized in terms of decreased anti-phase boundary energies at the given ordering energies, and a physical picture of the patterning reaction is presented. The application of this picture to Cu3Au is deemed plausible and future work proposed.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-02-28 without embargo terms","The student, Calvin Lear, accepted the attached license on 2016-11-10 at 01:49.","The student, Calvin Lear, submitted this Dissertation for approval on 2016-11-10 at 02:09.","This Dissertation was approved for publication on 2016-11-11 at 17:23.","DSpace SAF Submission Ingestion Package generated from Vireo submission #10228 on 2017-02-28 at 14:46:49","Made available in DSpace on 2017-03-01T15:48:30Z (GMT). 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The behavior of Cu3Au, an alloy with L12 chemical order, is investigated experimentally through in situ electron diffraction and dark-field transmission electron microscopy. Under irradiation with 500 keV Ne+ ions, our diffraction analysis reveals a similar, but steeper, trend in disordering rate as previously reported by resistivity. Further investigations by superlattice, dark-field imaging lead to the discovery of temperature and dose rate dependent alterations to the ordered microstructure of the alloy. The process appears to be driven by the nucleation of small, highly ordered domains within the existing microstructure. We attempt to simulate these and other disordering behaviors through a kinetic Monte Carlo method. For simplicity, we focus these investigations on two-dimensional, ordered AB alloys featuring various first and second neighbor ordering energies. Disorder is imposed in these simulated alloys through manipulation of vacancy-atom exchange rates and forced atomic replacement. For certain disordering-temperature conditions and ordering energies 𝐽2/𝐽1≲0.5, a previously unreported patterning of order is observed, dividing the ordered microstructure into competing, highly ordered domains. This behavior is rationalized in terms of decreased anti-phase boundary energies at the given ordering energies, and a physical picture of the patterning reaction is presented. The application of this picture to Cu3Au is deemed plausible and future work proposed.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2017-02-28 without embargo terms","The student, Calvin Lear, accepted the attached license on 2016-11-10 at 01:49.","The student, Calvin Lear, submitted this Dissertation for approval on 2016-11-10 at 02:09.","This Dissertation was approved for publication on 2016-11-11 at 17:23.","DSpace SAF Submission Ingestion Package generated from Vireo submission #10228 on 2017-02-28 at 14:46:49","Made available in DSpace on 2017-03-01T15:48:30Z (GMT). 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