{"id":{"repo_id":"uwo","oai_identifier":"oai:uwo.scholaris.ca:20.500.14721/39115"},"canonical_url":"https://search.dev.ndltd.org/etd/uwo/oai:uwo.scholaris.ca:20.500.14721/39115","repository":{"repo_id":"uwo","name":"Western University","base_url":"https://uwo.scholaris.ca/server/oai/request"},"display":{"title":"Multiscale In-Situ Characterization of Crystal Orientation, Temperature, and Microstructure Effects on Creep Defromation of Pure Magnesium and Mg-Al-RE Alloys","abstract":"Magnesium (Mg) and its alloys are the lightest structural metals, valued for their high strength-to-weight ratios in automotive and aerospace applications. Their broader use is restricted by limited creep resistance and pronounced anisotropy of plastic deformation, especially at elevated temperatures. This thesis examines how crystal orientation, temperature, and β-phase morphology govern creep behavior in pure Mg and AE44 alloys. Novel in-situ nanoindentation creep methods were developed using an indenter inside a SEM. Additional techniques included in-situ tensile creep testing, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and crystal plasticity finite element (CPFE) simulations. Together, these enabled orientation-sensitive analysis of creep behavior and links between microstructure and bulk creep response. The first part of the thesis investigates orientation effects in pure Mg via spherical indentation, showing strong anisotropy in lattice rotation and slip activity, with c-axis misorientation controlling basal slip and twinning. The second part develops in-situ Berkovich constant-load indentation creep tests at 25, 100, and 180 ˚C. Analysis of activation energy, activation volume, and athermal flow stress indicates that creep is dominated by obstacle-limited dislocation glide, while higher temperatures promote dynamic recovery. The final part studies high pressure die cast (HPDC) AE44 alloys (AE44-2 and AE44-4). Results reveal that β-phase morphology enhances creep resistance by obstructing dislocation glide and grain boundary sliding. A Hall-Petch-like relationship between β-phase spacing and creep displacement highlights microstructural refinement as a pathway to improved high-temperature performance. This work establishes advanced testing methodologies and provides new mechanistic insight into the creep behavior of Mg and AE44 alloys. The findings strengthen the understanding of orientation, temperature, and microstructural effects, offering guidance for alloy design to improve lightweight, high-temperature applications.","abstract_html":"Magnesium (Mg) and its alloys are the lightest structural metals, valued for their high strength-to-weight ratios in automotive and aerospace applications. Their broader use is restricted by limited creep resistance and pronounced anisotropy of plastic deformation, especially at elevated temperatures. This thesis examines how crystal orientation, temperature, and β-phase morphology govern creep behavior in pure Mg and AE44 alloys. Novel in-situ nanoindentation creep methods were developed using an indenter inside a SEM. Additional techniques included in-situ tensile creep testing, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and crystal plasticity finite element (CPFE) simulations. Together, these enabled orientation-sensitive analysis of creep behavior and links between microstructure and bulk creep response. The first part of the thesis investigates orientation effects in pure Mg via spherical indentation, showing strong anisotropy in lattice rotation and slip activity, with c-axis misorientation controlling basal slip and twinning. The second part develops in-situ Berkovich constant-load indentation creep tests at 25, 100, and 180 ˚C. Analysis of activation energy, activation volume, and athermal flow stress indicates that creep is dominated by obstacle-limited dislocation glide, while higher temperatures promote dynamic recovery. The final part studies high pressure die cast (HPDC) AE44 alloys (AE44-2 and AE44-4). Results reveal that β-phase morphology enhances creep resistance by obstructing dislocation glide and grain boundary sliding. A Hall-Petch-like relationship between β-phase spacing and creep displacement highlights microstructural refinement as a pathway to improved high-temperature performance. This work establishes advanced testing methodologies and provides new mechanistic insight into the creep behavior of Mg and AE44 alloys. The findings strengthen the understanding of orientation, temperature, and microstructural effects, offering guidance for alloy design to improve lightweight, high-temperature applications.","abstract_has_math":false,"creators":["Fu, Bolin"],"institution":"The University of Western Ontario","degree_name":"Ph D","degree_level":null,"degree_discipline":"Mechanical and Materials Engineering","degree_department":null,"school":null,"contributors":[],"advisors":["Klassen, Robert J.","Abdolvand, Hamidreza"],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-11-21","date_published":"2025-11-21","updated_at":"2026-07-27T21:56:11Z","subjects":["Magnesium","AE44 alloy","Creep behavior","In-situ indentation creep","In-situ tensile creep","Crystal orientation","β-phase morphology","SEM","EBSD","CPFE","Elevated-temperature deformation."],"languages":["en"],"rights":["Attribution-NonCommercial-NoDerivatives 4.0 International"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/20.500.14721/39115","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Klassen, Robert J.","Abdolvand, Hamidreza"]},{"key":"dc:creator","label":"Author","values":["Fu, Bolin"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2025-11-27T18:56:15Z"]},{"key":"dc:date.issued","label":"Date","values":["2025-11-21"]},{"key":"dc:publisher","label":"Institution","values":["The University of Western Ontario"]},{"key":"dc:type","label":"Dc Type","values":["thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical and Materials Engineering"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph D"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["The University of Western Ontario"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Magnesium","AE44 alloy","Creep behavior","In-situ indentation creep","In-situ tensile creep","Crystal orientation","β-phase morphology","SEM","EBSD","CPFE","Elevated-temperature deformation."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Attribution-NonCommercial-NoDerivatives 4.0 International"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/20.500.14721/39115"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Magnesium (Mg) and its alloys are the lightest structural metals, valued for their high strength-to-weight ratios in automotive and aerospace applications. Their broader use is restricted by limited creep resistance and pronounced anisotropy of plastic deformation, especially at elevated temperatures. This thesis examines how crystal orientation, temperature, and β-phase morphology govern creep behavior in pure Mg and AE44 alloys. Novel in-situ nanoindentation creep methods were developed using an indenter inside a SEM. Additional techniques included in-situ tensile creep testing, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and crystal plasticity finite element (CPFE) simulations. Together, these enabled orientation-sensitive analysis of creep behavior and links between microstructure and bulk creep response. The first part of the thesis investigates orientation effects in pure Mg via spherical indentation, showing strong anisotropy in lattice rotation and slip activity, with c-axis misorientation controlling basal slip and twinning. The second part develops in-situ Berkovich constant-load indentation creep tests at 25, 100, and 180 ˚C. Analysis of activation energy, activation volume, and athermal flow stress indicates that creep is dominated by obstacle-limited dislocation glide, while higher temperatures promote dynamic recovery. The final part studies high pressure die cast (HPDC) AE44 alloys (AE44-2 and AE44-4). Results reveal that β-phase morphology enhances creep resistance by obstructing dislocation glide and grain boundary sliding. A Hall-Petch-like relationship between β-phase spacing and creep displacement highlights microstructural refinement as a pathway to improved high-temperature performance. This work establishes advanced testing methodologies and provides new mechanistic insight into the creep behavior of Mg and AE44 alloys. The findings strengthen the understanding of orientation, temperature, and microstructural effects, offering guidance for alloy design to improve lightweight, high-temperature applications."]},{"key":"dc:title","label":"Title","values":["Multiscale In-Situ Characterization of Crystal Orientation, Temperature, and Microstructure Effects on Creep Defromation of Pure Magnesium and Mg-Al-RE Alloys"]}]}],"canonical_facts":{"dc:contributor.advisor":["Klassen, Robert J.","Abdolvand, Hamidreza"],"dc:creator":["Fu, Bolin"],"dc:date.accessioned":["2025-11-27T18:56:15Z"],"dc:date.issued":["2025-11-21"],"dc:description.abstract":["Magnesium (Mg) and its alloys are the lightest structural metals, valued for their high strength-to-weight ratios in automotive and aerospace applications. Their broader use is restricted by limited creep resistance and pronounced anisotropy of plastic deformation, especially at elevated temperatures. This thesis examines how crystal orientation, temperature, and β-phase morphology govern creep behavior in pure Mg and AE44 alloys. Novel in-situ nanoindentation creep methods were developed using an indenter inside a SEM. Additional techniques included in-situ tensile creep testing, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and crystal plasticity finite element (CPFE) simulations. Together, these enabled orientation-sensitive analysis of creep behavior and links between microstructure and bulk creep response. The first part of the thesis investigates orientation effects in pure Mg via spherical indentation, showing strong anisotropy in lattice rotation and slip activity, with c-axis misorientation controlling basal slip and twinning. The second part develops in-situ Berkovich constant-load indentation creep tests at 25, 100, and 180 ˚C. Analysis of activation energy, activation volume, and athermal flow stress indicates that creep is dominated by obstacle-limited dislocation glide, while higher temperatures promote dynamic recovery. The final part studies high pressure die cast (HPDC) AE44 alloys (AE44-2 and AE44-4). Results reveal that β-phase morphology enhances creep resistance by obstructing dislocation glide and grain boundary sliding. A Hall-Petch-like relationship between β-phase spacing and creep displacement highlights microstructural refinement as a pathway to improved high-temperature performance. This work establishes advanced testing methodologies and provides new mechanistic insight into the creep behavior of Mg and AE44 alloys. The findings strengthen the understanding of orientation, temperature, and microstructural effects, offering guidance for alloy design to improve lightweight, high-temperature applications."],"dc:identifier.uri":["https://hdl.handle.net/20.500.14721/39115"],"dc:language.iso":["en"],"dc:publisher":["The University of Western Ontario"],"dc:rights":["Attribution-NonCommercial-NoDerivatives 4.0 International"],"dc:subject":["Magnesium","AE44 alloy","Creep behavior","In-situ indentation creep","In-situ tensile creep","Crystal orientation","β-phase morphology","SEM","EBSD","CPFE","Elevated-temperature deformation."],"dc:title":["Multiscale In-Situ Characterization of Crystal Orientation, Temperature, and Microstructure Effects on Creep Defromation of Pure Magnesium and Mg-Al-RE Alloys"],"dc:type":["thesis"],"thesis:degree_discipline":["Mechanical and Materials Engineering"],"thesis:degree_name":["Ph D"],"thesis:institution_name":["The University of Western Ontario"]},"updated_at":"2026-07-27T21:56:11Z"}