\"Implementation of nanostructured metals and alloys for use in engineering applications requires a detailed knowledge of the underlying deformation mechanisms in these materials. It is well known that plastic deformation in metals and alloys is mainly mediated by dislocation activities. Nonetheless, TEM observations and atomistic simulations indicate that dislocation-mediated plasticity in nanostructured metals and alloys is significantly different from that in their coarse-grained counterparts. Therefore, this dissertation focuses on the exploration of the deformation mechanisms in nanostructured metals via crystal plasticity finite element modeling and simulation.
A statistical grain boundary dislocation source model accounting for dislocation nucleation and slip events was developed and incorporated into a 3D discrete crystal plasticity finite element model to study the mechanical behaviors of nanostructured metals including nanocrystalline, nanotwinned and heterogeneous lamellar structured metals. It was found that a Hall-Petch scaling of strength emerged from grain size limitation on dislocation source length, and that the Hall-Petch slope depended sensitively on texture and was proportional to the Taylor factor. Furthermore, it was shown that experimentally observed scaling between yield strength and twin thickness in columnar-grained nanotwinned Cu arose from statistical variability in dislocation source length, and that reducing twin thickness could increase plastic anisotropy as a result of the increase in mean stress to emit dislocations. In addition, it was revealed that a heterogeneous lamellar structure consisting of a nanocrystalline layer sandwiched between two coarse-grained lamellae could effectively homogenize plastic strain in the nanocrystalline layer, leading to suppressed strain heterogeneity and enhanced ductility\"--Abstract, page iv.
","abstract_html":"<p>"Implementation of nanostructured metals and alloys for use in engineering applications requires a detailed knowledge of the underlying deformation mechanisms in these materials. It is well known that plastic deformation in metals and alloys is mainly mediated by dislocation activities. Nonetheless, TEM observations and atomistic simulations indicate that dislocation-mediated plasticity in nanostructured metals and alloys is significantly different from that in their coarse-grained counterparts. Therefore, this dissertation focuses on the exploration of the deformation mechanisms in nanostructured metals via crystal plasticity finite element modeling and simulation.</p><p>A statistical grain boundary dislocation source model accounting for dislocation nucleation and slip events was developed and incorporated into a 3D discrete crystal plasticity finite element model to study the mechanical behaviors of nanostructured metals including nanocrystalline, nanotwinned and heterogeneous lamellar structured metals. It was found that a Hall-Petch scaling of strength emerged from grain size limitation on dislocation source length, and that the Hall-Petch slope depended sensitively on texture and was proportional to the Taylor factor. Furthermore, it was shown that experimentally observed scaling between yield strength and twin thickness in columnar-grained nanotwinned Cu arose from statistical variability in dislocation source length, and that reducing twin thickness could increase plastic anisotropy as a result of the increase in mean stress to emit dislocations. In addition, it was revealed that a heterogeneous lamellar structure consisting of a nanocrystalline layer sandwiched between two coarse-grained lamellae could effectively homogenize plastic strain in the nanocrystalline layer, leading to suppressed strain heterogeneity and enhanced ductility"--Abstract, page iv.</p>","abstract_has_math":false,"creators":["Yuan, Rui"],"institution":"Missouri University of Science and Technology","degree_name":"Ph. D. in Materials Science and Engineering","degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T03:18:43Z","subjects":["Materials Science and Engineering"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsmine.mst.edu/doctoral_dissertations/2590","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Yuan, Rui"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["Dissertation - Open Access"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. D. in Materials Science and Engineering"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Missouri University of Science and Technology"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Materials Science and Engineering"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsmine.mst.edu/doctoral_dissertations/2590"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["\"Implementation of nanostructured metals and alloys for use in engineering applications requires a detailed knowledge of the underlying deformation mechanisms in these materials. It is well known that plastic deformation in metals and alloys is mainly mediated by dislocation activities. Nonetheless, TEM observations and atomistic simulations indicate that dislocation-mediated plasticity in nanostructured metals and alloys is significantly different from that in their coarse-grained counterparts. Therefore, this dissertation focuses on the exploration of the deformation mechanisms in nanostructured metals via crystal plasticity finite element modeling and simulation.
A statistical grain boundary dislocation source model accounting for dislocation nucleation and slip events was developed and incorporated into a 3D discrete crystal plasticity finite element model to study the mechanical behaviors of nanostructured metals including nanocrystalline, nanotwinned and heterogeneous lamellar structured metals. It was found that a Hall-Petch scaling of strength emerged from grain size limitation on dislocation source length, and that the Hall-Petch slope depended sensitively on texture and was proportional to the Taylor factor. Furthermore, it was shown that experimentally observed scaling between yield strength and twin thickness in columnar-grained nanotwinned Cu arose from statistical variability in dislocation source length, and that reducing twin thickness could increase plastic anisotropy as a result of the increase in mean stress to emit dislocations. In addition, it was revealed that a heterogeneous lamellar structure consisting of a nanocrystalline layer sandwiched between two coarse-grained lamellae could effectively homogenize plastic strain in the nanocrystalline layer, leading to suppressed strain heterogeneity and enhanced ductility\"--Abstract, page iv.
"]},{"key":"dc:title","label":"Title","values":["Understanding the deformation mechanisms in nanostructured metals by a novel discrete crystal plasticity finite element model"]}]}],"canonical_facts":{"dc:creator":["Yuan, Rui"],"dc:description.abstract":["\"Implementation of nanostructured metals and alloys for use in engineering applications requires a detailed knowledge of the underlying deformation mechanisms in these materials. It is well known that plastic deformation in metals and alloys is mainly mediated by dislocation activities. Nonetheless, TEM observations and atomistic simulations indicate that dislocation-mediated plasticity in nanostructured metals and alloys is significantly different from that in their coarse-grained counterparts. Therefore, this dissertation focuses on the exploration of the deformation mechanisms in nanostructured metals via crystal plasticity finite element modeling and simulation.
A statistical grain boundary dislocation source model accounting for dislocation nucleation and slip events was developed and incorporated into a 3D discrete crystal plasticity finite element model to study the mechanical behaviors of nanostructured metals including nanocrystalline, nanotwinned and heterogeneous lamellar structured metals. It was found that a Hall-Petch scaling of strength emerged from grain size limitation on dislocation source length, and that the Hall-Petch slope depended sensitively on texture and was proportional to the Taylor factor. Furthermore, it was shown that experimentally observed scaling between yield strength and twin thickness in columnar-grained nanotwinned Cu arose from statistical variability in dislocation source length, and that reducing twin thickness could increase plastic anisotropy as a result of the increase in mean stress to emit dislocations. In addition, it was revealed that a heterogeneous lamellar structure consisting of a nanocrystalline layer sandwiched between two coarse-grained lamellae could effectively homogenize plastic strain in the nanocrystalline layer, leading to suppressed strain heterogeneity and enhanced ductility\"--Abstract, page iv.
"],"dc:identifier":["https://scholarsmine.mst.edu/doctoral_dissertations/2590"],"dc:subject":["Materials Science and Engineering"],"dc:title":["Understanding the deformation mechanisms in nanostructured metals by a novel discrete crystal plasticity finite element model"],"dc:type":["Dissertation - Open Access"],"thesis:degree_name":["Ph. D. in Materials Science and Engineering"],"thesis:institution_name":["Missouri University of Science and Technology"]},"updated_at":"2026-07-24T03:18:43Z"}