{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/19888"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/19888","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Oxidation behavior of laser clad nickel-aluminum-chromium-hafnium alloys","abstract":"Controversy regarding the mechanism(s) responsible for the retention of alumina scales formed on NiAlCr alloys containing reactive elements remains. Laser cladding is the process where a mechanical mixture of powders is rapidly melted and fused to a solid substrate using a CO$\\sb2$ laser. The effects of laser cladding upon scale retention on NiAlCrHf alloys after cyclic and isothermal exposure to air were investigated. The stress developed in the scale during cooling after exposure was estimated using a thermoelastic model. Additions of up to $\\approx$2${1\\over2}$ wt % Hf increasingly promote retention of scales grown at 1200$\\sp\\circ$C. Laser clad samples containing $\\approx$2${1\\over2}$ wt % Hf retained almost intact scales. The improvement in scale retention is due to improved toughness in scales containing hafnia-rich polycrystallites possibly via microcracking initiated by anisotropic thermall contraction of the hafnia. Laser cladding provides a large concentration of $\\approx$1$\\mu$m Hf-rich particles that are precursors of the hafnia in the scale as well as a fine dendrite spacing that reduces the mean free distance between particles.","abstract_html":"Controversy regarding the mechanism(s) responsible for the retention of alumina scales formed on NiAlCr alloys containing reactive elements remains. Laser cladding is the process where a mechanical mixture of powders is rapidly melted and fused to a solid substrate using a CO$\\sb2$ laser. The effects of laser cladding upon scale retention on NiAlCrHf alloys after cyclic and isothermal exposure to air were investigated. The stress developed in the scale during cooling after exposure was estimated using a thermoelastic model. Additions of up to $\\approx$2${1\\over2}$ wt % Hf increasingly promote retention of scales grown at 1200$\\sp\\circ$C. Laser clad samples containing $\\approx$2${1\\over2}$ wt % Hf retained almost intact scales. The improvement in scale retention is due to improved toughness in scales containing hafnia-rich polycrystallites possibly via microcracking initiated by anisotropic thermall contraction of the hafnia. Laser cladding provides a large concentration of $\\approx$1<span class=\"etd-inline-math\">&mu;</span>m Hf-rich particles that are precursors of the hafnia in the scale as well as a fine dendrite spacing that reduces the mean free distance between particles.","abstract_has_math":true,"creators":["Ribaudo, Carl Robert"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Materials Science and Engineering","degree_department":null,"school":null,"contributors":["Mazumder, Jyotirmoy"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T12:21:53Z","date_published":"2011-05-07T12:21:53Z","updated_at":"2026-07-22T22:25:14Z","subjects":["Engineering, Metallurgy"],"languages":["eng"],"rights":["Copyright 1991 Ribaudo, Carl Robert"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9136713","(UMI)AAI9136713"],"render_values":[{"text":"AAI9136713","href":null,"code":true},{"text":"(UMI)AAI9136713","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/19888","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Mazumder, Jyotirmoy"]},{"key":"dc:creator","label":"Author","values":["Ribaudo, Carl Robert"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T12:21:53Z","10000-01-01","1991"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science and Engineering"]},{"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":["Engineering, Metallurgy"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1991 Ribaudo, Carl Robert"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9136713","(UMI)AAI9136713","http://hdl.handle.net/2142/19888"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Controversy regarding the mechanism(s) responsible for the retention of alumina scales formed on NiAlCr alloys containing reactive elements remains. Laser cladding is the process where a mechanical mixture of powders is rapidly melted and fused to a solid substrate using a CO$\\sb2$ laser. The effects of laser cladding upon scale retention on NiAlCrHf alloys after cyclic and isothermal exposure to air were investigated. The stress developed in the scale during cooling after exposure was estimated using a thermoelastic model. Additions of up to $\\approx$2${1\\over2}$ wt % Hf increasingly promote retention of scales grown at 1200$\\sp\\circ$C. Laser clad samples containing $\\approx$2${1\\over2}$ wt % Hf retained almost intact scales. The improvement in scale retention is due to improved toughness in scales containing hafnia-rich polycrystallites possibly via microcracking initiated by anisotropic thermall contraction of the hafnia. Laser cladding provides a large concentration of $\\approx$1$\\mu$m Hf-rich particles that are precursors of the hafnia in the scale as well as a fine dendrite spacing that reduces the mean free distance between particles.","Made available in DSpace on 2011-05-07T12:21:53Z (GMT). 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Laser cladding is the process where a mechanical mixture of powders is rapidly melted and fused to a solid substrate using a CO$\\sb2$ laser. The effects of laser cladding upon scale retention on NiAlCrHf alloys after cyclic and isothermal exposure to air were investigated. The stress developed in the scale during cooling after exposure was estimated using a thermoelastic model. Additions of up to $\\approx$2${1\\over2}$ wt % Hf increasingly promote retention of scales grown at 1200$\\sp\\circ$C. Laser clad samples containing $\\approx$2${1\\over2}$ wt % Hf retained almost intact scales. The improvement in scale retention is due to improved toughness in scales containing hafnia-rich polycrystallites possibly via microcracking initiated by anisotropic thermall contraction of the hafnia. Laser cladding provides a large concentration of $\\approx$1$\\mu$m Hf-rich particles that are precursors of the hafnia in the scale as well as a fine dendrite spacing that reduces the mean free distance between particles.","Made available in DSpace on 2011-05-07T12:21:53Z (GMT). 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