{"id":{"repo_id":"mississippi","oai_identifier":"oai:egrove.olemiss.edu:etd-1687"},"canonical_url":"https://search.dev.ndltd.org/etd/mississippi/oai:egrove.olemiss.edu:etd-1687","repository":{"repo_id":"mississippi","name":"University of Mississippi","base_url":"https://egrove.olemiss.edu/do/oai/"},"display":{"title":"Phase Stability In Cobalt-Based L12 Quaternary Intermetallics From Density Functional Theory","abstract":"The effects of higher order alloying additions (Mo, Ti, Ta, Hf, Fe, V) on the phase stability of L12 (γ’) intermetallics have been studied via first-principles. A 32 atom special-quasi-random structure was used to mimic the experimentally observed solid solution sublattice. Density of states distributions were generated in order to directly observe the impact of alloying additions on the position of the pseudogap and number of states at the Fermi level. Charge density differences across the supercell were visualized to analyze changes in bonding behavior. The results indicate that substitutions of Ti, Ta, and Hf in place of the central W atom increase phase stability by lowering the number of states at the Fermi level and decreasing the energy of the pseudogap relative to the unperturbed structure. Additionally, these substitutions increase the directional nature of the bond with nearest neighbor Co atoms. In particular, Co-Al bonds are reinforced at the expense of adjacent Co-W bonds which is expected to prolong dissociation of Co-Al bonds. Substitution of Fe led to a pronounced decrease in phase stability and directional bonding, indicating its inability to stabilize the base configuration or increase the bonding strength. V and Mo substitutions maintained the parent electron distribution to a greater degree than Ti, Ta, Hf, or Fe. However, V was shown to decrease the energy of the pseudogap by a significant amount and resembled the proposed ?’ stabilizers more so than Mo.","abstract_html":"The effects of higher order alloying additions (Mo, Ti, Ta, Hf, Fe, V) on the phase stability of L12 (γ’) intermetallics have been studied via first-principles. A 32 atom special-quasi-random structure was used to mimic the experimentally observed solid solution sublattice. Density of states distributions were generated in order to directly observe the impact of alloying additions on the position of the pseudogap and number of states at the Fermi level. Charge density differences across the supercell were visualized to analyze changes in bonding behavior. The results indicate that substitutions of Ti, Ta, and Hf in place of the central W atom increase phase stability by lowering the number of states at the Fermi level and decreasing the energy of the pseudogap relative to the unperturbed structure. Additionally, these substitutions increase the directional nature of the bond with nearest neighbor Co atoms. In particular, Co-Al bonds are reinforced at the expense of adjacent Co-W bonds which is expected to prolong dissociation of Co-Al bonds. Substitution of Fe led to a pronounced decrease in phase stability and directional bonding, indicating its inability to stabilize the base configuration or increase the bonding strength. V and Mo substitutions maintained the parent electron distribution to a greater degree than Ti, Ta, Hf, or Fe. However, V was shown to decrease the energy of the pseudogap by a significant amount and resembled the proposed ?’ stabilizers more so than Mo.","abstract_has_math":false,"creators":["Earwood, William"],"institution":null,"degree_name":"M.S. in Engineering Science","degree_level":"Thesis","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":["Amrita Mishra"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2017,"date_issued":"2017-01-01T08:00:00Z","date_published":"2017-01-01T08:00:00Z","updated_at":"2026-07-24T03:05:53Z","subjects":["Cobalt-Aluminum-Tungsten","Density Functional Theory","Gamma-Gamma Prime","L12","Superalloys","Materials Science and Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://egrove.olemiss.edu/etd/688","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Amrita Mishra"]},{"key":"dc:creator","label":"Author","values":["Earwood, William"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2019-06-20T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S. in Engineering Science"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Cobalt-Aluminum-Tungsten","Density Functional Theory","Gamma-Gamma Prime","L12","Superalloys","Materials Science and Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://egrove.olemiss.edu/etd/688"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The effects of higher order alloying additions (Mo, Ti, Ta, Hf, Fe, V) on the phase stability of L12 (γ’) intermetallics have been studied via first-principles. A 32 atom special-quasi-random structure was used to mimic the experimentally observed solid solution sublattice. Density of states distributions were generated in order to directly observe the impact of alloying additions on the position of the pseudogap and number of states at the Fermi level. Charge density differences across the supercell were visualized to analyze changes in bonding behavior. The results indicate that substitutions of Ti, Ta, and Hf in place of the central W atom increase phase stability by lowering the number of states at the Fermi level and decreasing the energy of the pseudogap relative to the unperturbed structure. Additionally, these substitutions increase the directional nature of the bond with nearest neighbor Co atoms. In particular, Co-Al bonds are reinforced at the expense of adjacent Co-W bonds which is expected to prolong dissociation of Co-Al bonds. Substitution of Fe led to a pronounced decrease in phase stability and directional bonding, indicating its inability to stabilize the base configuration or increase the bonding strength. V and Mo substitutions maintained the parent electron distribution to a greater degree than Ti, Ta, Hf, or Fe. However, V was shown to decrease the energy of the pseudogap by a significant amount and resembled the proposed ?’ stabilizers more so than Mo."]},{"key":"dc:title","label":"Title","values":["Phase Stability In Cobalt-Based L12 Quaternary Intermetallics From Density Functional Theory"]}]}],"canonical_facts":{"dc:contributor":["Amrita Mishra"],"dc:creator":["Earwood, William"],"dc:date.available":["2019-06-20T07:00:00Z"],"dc:description.abstract":["The effects of higher order alloying additions (Mo, Ti, Ta, Hf, Fe, V) on the phase stability of L12 (γ’) intermetallics have been studied via first-principles. A 32 atom special-quasi-random structure was used to mimic the experimentally observed solid solution sublattice. Density of states distributions were generated in order to directly observe the impact of alloying additions on the position of the pseudogap and number of states at the Fermi level. Charge density differences across the supercell were visualized to analyze changes in bonding behavior. The results indicate that substitutions of Ti, Ta, and Hf in place of the central W atom increase phase stability by lowering the number of states at the Fermi level and decreasing the energy of the pseudogap relative to the unperturbed structure. Additionally, these substitutions increase the directional nature of the bond with nearest neighbor Co atoms. In particular, Co-Al bonds are reinforced at the expense of adjacent Co-W bonds which is expected to prolong dissociation of Co-Al bonds. Substitution of Fe led to a pronounced decrease in phase stability and directional bonding, indicating its inability to stabilize the base configuration or increase the bonding strength. V and Mo substitutions maintained the parent electron distribution to a greater degree than Ti, Ta, Hf, or Fe. However, V was shown to decrease the energy of the pseudogap by a significant amount and resembled the proposed ?’ stabilizers more so than Mo."],"dc:identifier":["https://egrove.olemiss.edu/etd/688"],"dc:subject":["Cobalt-Aluminum-Tungsten","Density Functional Theory","Gamma-Gamma Prime","L12","Superalloys","Materials Science and Engineering"],"dc:title":["Phase Stability In Cobalt-Based L12 Quaternary Intermetallics From Density Functional Theory"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["M.S. in Engineering Science"]},"updated_at":"2026-07-24T03:05:53Z"}