{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/71837"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/71837","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Electrical Resistance Studies of Hydrogen Diffusion and of Hydride Precipitation in Niobium","abstract":"Diffusion of hydrogen in niobium was studied by using thermotransport to establish a concentration gradient in a periodic width modulated sample. A sensitive Kelvin double bridge allowed the kinetics of return to uniform concentration to be monitored. In undeformed Nb, the Arhennius plot exhibited a curvature, in agreement with previous results. Deformation indiced by hydride precipitation and by cold work removed the curvature, and increased the fitted values of Do and Q in D = D(,o)e('-Q/kT). These effects are considered to be due to dislocation trapping of H. The undeformed data were fit to the Flynn-Stoneham quantum tunneling model of diffusion. The value for the lattice Debye temperature found was unphysically high (900 K); the validity of the model is therefore in question.","abstract_html":"Diffusion of hydrogen in niobium was studied by using thermotransport to establish a concentration gradient in a periodic width modulated sample. A sensitive Kelvin double bridge allowed the kinetics of return to uniform concentration to be monitored. In undeformed Nb, the Arhennius plot exhibited a curvature, in agreement with previous results. Deformation indiced by hydride precipitation and by cold work removed the curvature, and increased the fitted values of Do and Q in D = D(,o)e('-Q/kT). These effects are considered to be due to dislocation trapping of H. The undeformed data were fit to the Flynn-Stoneham quantum tunneling model of diffusion. The value for the lattice Debye temperature found was unphysically high (900 K); the validity of the model is therefore in question.","abstract_has_math":false,"creators":["Clark, Elliot Andrew"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Metallurgical Engineering","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2014,"date_issued":"2014-12-16T20:52:09Z","date_published":"2014-12-16T20:52:09Z","updated_at":"2026-07-22T22:26:05Z","subjects":["Engineering, Metallurgy"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["(UMI)AAI8701464"],"render_values":[{"text":"(UMI)AAI8701464","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/71837","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Clark, Elliot Andrew"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2014-12-16T20:52:09Z","10000-01-01","1986"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Metallurgical 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":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/71837","(UMI)AAI8701464"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Diffusion of hydrogen in niobium was studied by using thermotransport to establish a concentration gradient in a periodic width modulated sample. A sensitive Kelvin double bridge allowed the kinetics of return to uniform concentration to be monitored. In undeformed Nb, the Arhennius plot exhibited a curvature, in agreement with previous results. Deformation indiced by hydride precipitation and by cold work removed the curvature, and increased the fitted values of Do and Q in D = D(,o)e('-Q/kT). These effects are considered to be due to dislocation trapping of H. The undeformed data were fit to the Flynn-Stoneham quantum tunneling model of diffusion. The value for the lattice Debye temperature found was unphysically high (900 K); the validity of the model is therefore in question.","The precipitation of hydride in Nb was studied by balancing the Kelvin double bridge such that the bridge output was proportional to the concentration of unprecipitated hydrogen, and following the concentration of free hydrogen with temperature. Repeated cycles of precipitation and reversion showed at first a decreasing, and then constant hysteresis (difference between precipitation and reversion temperatures). Prior cold work did not affect the precipitation in any way. The formation of a local dislocation structure for hydride precipitation may explain this behavior. Increasing the heating/cooling rate increased the precipitation/reversion temperatures. Fits of the curves to an equation of the solvus give values for the constrained solvus that differ from previous investigations. The amount of isothermal hydride precipitation decreases with cycling, but the isothermal rate is much less affected. The mechanism of isothermal hydride precipitation is unclear: dislocation processes are postulated.","Made available in DSpace on 2014-12-16T20:52:09Z (GMT). No. of bitstreams: 1 8701464.pdf: 3218335 bytes, checksum: a63b2905f3746fc5f2605b405eb62f68 (MD5) Previous issue date: 1986","Embargo set by: Seth Robbins for item 72003 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","116 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986."]},{"key":"dc:title","label":"Title","values":["Electrical Resistance Studies of Hydrogen Diffusion and of Hydride Precipitation in Niobium"]}]}],"canonical_facts":{"dc:creator":["Clark, Elliot Andrew"],"dc:date":["2014-12-16T20:52:09Z","10000-01-01","1986"],"dc:description":["Diffusion of hydrogen in niobium was studied by using thermotransport to establish a concentration gradient in a periodic width modulated sample. A sensitive Kelvin double bridge allowed the kinetics of return to uniform concentration to be monitored. In undeformed Nb, the Arhennius plot exhibited a curvature, in agreement with previous results. Deformation indiced by hydride precipitation and by cold work removed the curvature, and increased the fitted values of Do and Q in D = D(,o)e('-Q/kT). These effects are considered to be due to dislocation trapping of H. The undeformed data were fit to the Flynn-Stoneham quantum tunneling model of diffusion. The value for the lattice Debye temperature found was unphysically high (900 K); the validity of the model is therefore in question.","The precipitation of hydride in Nb was studied by balancing the Kelvin double bridge such that the bridge output was proportional to the concentration of unprecipitated hydrogen, and following the concentration of free hydrogen with temperature. Repeated cycles of precipitation and reversion showed at first a decreasing, and then constant hysteresis (difference between precipitation and reversion temperatures). Prior cold work did not affect the precipitation in any way. The formation of a local dislocation structure for hydride precipitation may explain this behavior. Increasing the heating/cooling rate increased the precipitation/reversion temperatures. Fits of the curves to an equation of the solvus give values for the constrained solvus that differ from previous investigations. The amount of isothermal hydride precipitation decreases with cycling, but the isothermal rate is much less affected. The mechanism of isothermal hydride precipitation is unclear: dislocation processes are postulated.","Made available in DSpace on 2014-12-16T20:52:09Z (GMT). No. of bitstreams: 1 8701464.pdf: 3218335 bytes, checksum: a63b2905f3746fc5f2605b405eb62f68 (MD5) Previous issue date: 1986","Embargo set by: Seth Robbins for item 72003 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs","U of I Only","116 p.","Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1986."],"dc:identifier":["http://hdl.handle.net/2142/71837","(UMI)AAI8701464"],"dc:subject":["Engineering, Metallurgy"],"dc:title":["Electrical Resistance Studies of Hydrogen Diffusion and of Hydride Precipitation in Niobium"],"dc:type":["text"],"thesis:degree_discipline":["Metallurgical Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:05Z"}