{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/87147"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/87147","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Deformation and fracture behavior during annealing of residually stressed polycrystalline aluminum oxide","abstract":"Three types of polycrystalline aluminum oxide, with varying amounts of impurities, were tempered and then annealed to study the behavior of residual stress relaxation. Results from microprobe analysis, thermal expansion analysis, annealed strength measurements, and scanning electron fractography clearly indicate stress relaxation at annealing temperatures occurred by elastic creep through crack nucleation and growth in regions under tensile stresses. From the scanning electron fractographs, it was found that intergranular glassy phase played an important role in the crack formation and propagation. At elevated temperature, viscous intergranular glassy phase behaved as an adhesive layer and when under tensile stresses caused de-adhesion of grain-boundaries or the formation of cracks. Fine-grained aluminas, with little or no glassy phase, exhibited both sub-critical and critical crack propagation. Since cracks decrease the load-carrying ability of the aluminas, it was concluded that by minimizing the glassy phase, porosity, grain size and residual stresses one can suppress crack formation.","abstract_html":"Three types of polycrystalline aluminum oxide, with varying amounts of impurities, were tempered and then annealed to study the behavior of residual stress relaxation. Results from microprobe analysis, thermal expansion analysis, annealed strength measurements, and scanning electron fractography clearly indicate stress relaxation at annealing temperatures occurred by elastic creep through crack nucleation and growth in regions under tensile stresses. From the scanning electron fractographs, it was found that intergranular glassy phase played an important role in the crack formation and propagation. At elevated temperature, viscous intergranular glassy phase behaved as an adhesive layer and when under tensile stresses caused de-adhesion of grain-boundaries or the formation of cracks. Fine-grained aluminas, with little or no glassy phase, exhibited both sub-critical and critical crack propagation. Since cracks decrease the load-carrying ability of the aluminas, it was concluded that by minimizing the glassy phase, porosity, grain size and residual stresses one can suppress crack formation.","abstract_has_math":false,"creators":["Tree, Yenho Kuo"],"institution":"Virginia Polytechnic Institute and State University","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Materials Engineering","degree_department":"Materials Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1982,"date_issued":"1982","date_published":"1982","updated_at":"2026-07-22T22:19:24Z","subjects":[],"languages":["en_US"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/87147","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Materials Engineering"]},{"key":"dc:creator","label":"Author","values":["Tree, Yenho Kuo"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2019-01-31T17:50:37Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2019-01-31T17:50:37Z"]},{"key":"dc:date.issued","label":"Date","values":["1982"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en_US"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/87147"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Three types of polycrystalline aluminum oxide, with varying amounts of impurities, were tempered and then annealed to study the behavior of residual stress relaxation. Results from microprobe analysis, thermal expansion analysis, annealed strength measurements, and scanning electron fractography clearly indicate stress relaxation at annealing temperatures occurred by elastic creep through crack nucleation and growth in regions under tensile stresses. From the scanning electron fractographs, it was found that intergranular glassy phase played an important role in the crack formation and propagation. At elevated temperature, viscous intergranular glassy phase behaved as an adhesive layer and when under tensile stresses caused de-adhesion of grain-boundaries or the formation of cracks. Fine-grained aluminas, with little or no glassy phase, exhibited both sub-critical and critical crack propagation. Since cracks decrease the load-carrying ability of the aluminas, it was concluded that by minimizing the glassy phase, porosity, grain size and residual stresses one can suppress crack formation."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Deformation and fracture behavior during annealing of residually stressed polycrystalline aluminum oxide"]}]}],"canonical_facts":{"dc:contributor.department":["Materials Engineering"],"dc:creator":["Tree, Yenho Kuo"],"dc:date.accessioned":["2019-01-31T17:50:37Z"],"dc:date.available":["2019-01-31T17:50:37Z"],"dc:date.issued":["1982"],"dc:description.abstract":["Three types of polycrystalline aluminum oxide, with varying amounts of impurities, were tempered and then annealed to study the behavior of residual stress relaxation. Results from microprobe analysis, thermal expansion analysis, annealed strength measurements, and scanning electron fractography clearly indicate stress relaxation at annealing temperatures occurred by elastic creep through crack nucleation and growth in regions under tensile stresses. From the scanning electron fractographs, it was found that intergranular glassy phase played an important role in the crack formation and propagation. At elevated temperature, viscous intergranular glassy phase behaved as an adhesive layer and when under tensile stresses caused de-adhesion of grain-boundaries or the formation of cracks. Fine-grained aluminas, with little or no glassy phase, exhibited both sub-critical and critical crack propagation. Since cracks decrease the load-carrying ability of the aluminas, it was concluded that by minimizing the glassy phase, porosity, grain size and residual stresses one can suppress crack formation."],"dc:description.degree":["Master of Science"],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10919/87147"],"dc:language.iso":["en_US"],"dc:publisher":["Virginia Polytechnic Institute and State University"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Deformation and fracture behavior during annealing of residually stressed polycrystalline aluminum oxide"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Materials Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:24Z"}