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You searched for subject:(multi principal element). Showing records 1 – 3 of 3 total matches.

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University of North Texas

1. Mridha, Sanghita. Structure Evolution and Nano-Mechanical Behavior of Bulk Metallic Glasses and Multi-Principal Element Alloys.

Degree: 2017, University of North Texas

Bulk metallic glasses and multi-principal element alloys represent relatively new classes of multi-component engineering materials designed for satisfying multiple functionalities simultaneously. Correlating the microstructure with mechanical behavior (at the microstructural length-scales) in these materials is key to understanding their performance. In this study, the structure evolution and nano-mechanical behavior of these two classes of materials was investigated with the objective of fundamental scientific understanding of their properties. The structure evolution, high temperature nano-mechanical behavior, and creep of two Zr-based alloys was studied: Zr41.2Ti13.8Cu12.5Ni10.0Be22 (Vitreloy1) and Zr52.5Ti5Cu17.9Ni14.6All0 (Vitreloy105). Devitrification was found to proceed via the formation of a metastable icosahedral phase with five-fold symmetry. The deformation mechanism changes from inhomogeneous or serrated flow to homogenous flow near 0.9Tg, where Tg is the glass transition temperature. The creep activation energy for Vitreloy1 and Vitreloy105 were 144 kJ/mol and 125 kJ/mol, respectively in the range of room temperature to 0.75Tg. The apparent activation energy increased drastically to 192 kJ/mol for Vitreloy1 and 215 kJ/mol for Vitreloy105 in the range of 0.9Tg to Tg, indicating a change in creep mechanism. Structure evolution in catalytic amorphous alloys, Pt57.5Cu14.7Ni5.3P22.5 and Pd43Cu27Ni10P20, was studied using 3D atom probe tomography and elemental segregation between different phases and the interface characteristics were identified. The structure evolution of three multi-principal element alloys were investigated namely CoCrNi, CoCrFeMnNi, and Al0.1CoCrFeNi. All three alloys formed a single-phase FCC structure in as-cast, cold worked and recrystallized state. No secondary phases precipitated after prolonged heat treatment or mechanical working. The multi-principal element alloys showed less strain gradient plasticity compared to pure metals like Ni during nano-indentation. This was attributed to the highly distorted lattice which resulted in lesser density of geometrically necessary dislocations (GNDs). Dislocation nucleation was studied by low load indentation along with the evaluation of activation volume and activation energy. This was done using a statistical approach of analyzing the "pop-in" load marking incipient plasticity. The strain rate sensitivity of nanocrystalline Al0.1CoCrFeNi alloy was determined by in situ compression of nano-pillars in a Pico-indenter. The nanocrystalline alloy demonstrated a yield strength of ~ 2.4 GPa, ten times greater than its coarse grained counterpart. The nanocrystalline alloy exhibited high strain rate sensitivity index of 0.043 and activation volume of 5b3 suggesting grain boundary dislocation nucleation. Advisors/Committee Members: Du, Jincheng, Dahotre, Narendra B., Banerjee, Rajarshi, Young, Marcus L., Mukherjee, Sundeep.

Subjects/Keywords: Bulk metallic glass; Multi-principal element alloy

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APA (6th Edition):

Mridha, S. (2017). Structure Evolution and Nano-Mechanical Behavior of Bulk Metallic Glasses and Multi-Principal Element Alloys. (Thesis). University of North Texas. Retrieved from https://digital.library.unt.edu/ark:/67531/metadc984260/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Mridha, Sanghita. “Structure Evolution and Nano-Mechanical Behavior of Bulk Metallic Glasses and Multi-Principal Element Alloys.” 2017. Thesis, University of North Texas. Accessed July 19, 2019. https://digital.library.unt.edu/ark:/67531/metadc984260/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Mridha, Sanghita. “Structure Evolution and Nano-Mechanical Behavior of Bulk Metallic Glasses and Multi-Principal Element Alloys.” 2017. Web. 19 Jul 2019.

Vancouver:

Mridha S. Structure Evolution and Nano-Mechanical Behavior of Bulk Metallic Glasses and Multi-Principal Element Alloys. [Internet] [Thesis]. University of North Texas; 2017. [cited 2019 Jul 19]. Available from: https://digital.library.unt.edu/ark:/67531/metadc984260/.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Mridha S. Structure Evolution and Nano-Mechanical Behavior of Bulk Metallic Glasses and Multi-Principal Element Alloys. [Thesis]. University of North Texas; 2017. Available from: https://digital.library.unt.edu/ark:/67531/metadc984260/

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


The Ohio State University

2. Slone, Connor. Influence of composition and processing on the mechanical response of multi-principal element alloys containing Ni, Cr, and Co.

Degree: PhD, Materials Science and Engineering, 2019, The Ohio State University

Conventional metal alloys are made up of one predominant base metal and smaller quantities of one or more additional alloying elements. Although this strategy has successfully produced all metals currently in use, a new multi-principal element paradigm is emerging in which highly-alloyed compositions lack a clear base metal. This foray into previously unexplored composition space has produced new alloys with excellent combinations of strength, ductility, and other properties, particularly when using 3d transition metal elements. This work concerns multi-principal element alloys comprising transition metals chromium, cobalt, and nickel.Key findings include a more detailed understanding of heterogeneous microstructures and their effect on alloy strength and ductility; new indications that deformation twinning may be unnecessary for high strain-hardening rates and good ductility; and elucidation of the discontinuous coarsening effect along grain boundaries in highly-alloyed CrCoNi-base materials like commercial superalloy 740H. These results can be broadly applied to other multi-principal element alloys and austenitic steels. Advisors/Committee Members: Mills, Michael (Advisor).

Subjects/Keywords: Materials Science; MPE; HEA; multi-principal element; high-entropy alloys; medium entropy alloys; superalloys; ultra-high strength

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Slone, C. (2019). Influence of composition and processing on the mechanical response of multi-principal element alloys containing Ni, Cr, and Co. (Doctoral Dissertation). The Ohio State University. Retrieved from http://rave.ohiolink.edu/etdc/view?acc_num=osu1555522223986934

Chicago Manual of Style (16th Edition):

Slone, Connor. “Influence of composition and processing on the mechanical response of multi-principal element alloys containing Ni, Cr, and Co.” 2019. Doctoral Dissertation, The Ohio State University. Accessed July 19, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555522223986934.

MLA Handbook (7th Edition):

Slone, Connor. “Influence of composition and processing on the mechanical response of multi-principal element alloys containing Ni, Cr, and Co.” 2019. Web. 19 Jul 2019.

Vancouver:

Slone C. Influence of composition and processing on the mechanical response of multi-principal element alloys containing Ni, Cr, and Co. [Internet] [Doctoral dissertation]. The Ohio State University; 2019. [cited 2019 Jul 19]. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1555522223986934.

Council of Science Editors:

Slone C. Influence of composition and processing on the mechanical response of multi-principal element alloys containing Ni, Cr, and Co. [Doctoral Dissertation]. The Ohio State University; 2019. Available from: http://rave.ohiolink.edu/etdc/view?acc_num=osu1555522223986934

3. Maria Isabel Vega Martinez. Discriminação de alface orgânicas e convencionais usando determinação elementar e métodos quimiométricos.

Degree: 2011, Universidade Federal do ABC

Alimentos como os vegetais podem ser cultivados de diferentes maneiras (orgânica, convencional e hidropônica). Na era dos agrotóxicos cresce a procura pelos alimentos orgânicos, os quais são cultivados em terra fértil sem uso de fertilizantes químicos inorgânicos ou produtos agrotóxicos. Uma vez que esses alimentos orgânicos necessitam de um cultivo diferenciado, os custos com a sua produção são mais onerosos. Associado a isso e a falta de fiscalização pelos órgãos reguladores, a necessidade de ferramenta analítica para controlar possíveis fraudes são necessárias. Nesse sentido, o presente trabalho utiliza a determinação do teor de nitrato, elementos essenciais (Ca, Mg, K, Fe, Cu, Na, Mn, Mo, Co, Ni, Zn), tóxicos (Al, Hg) e o uso de ferramentas quimiometricas tais como: PCA (análise de componente principal) e HCA (Análise de componente hierárquica) visando à discriminação do tipo de cultivo das alfaces. As técnicas de ICP OES (Espectrometria de Emissão Óptica com Plasma Indutivamente Acoplado) e LIBS (Espectrometria de Emissão Óptica com Plasma Induzido por Laser) foram utilizadas na determinação elementar e aquisição de sinais analíticos que serviram de dados de entrada dos métodos de reconhecimento de padrão não-supervisionados. O DMA (Analisador direto de mercúrio) foi utilizado para a determinação de Hg e na determinação de nitrato foi utilizada DPV (Voltametria de pulso diferencial). A diferenciação das alfaces foi realizada de 2 formas: 1) Em função das concentrações obtidas por ICP OES, DPV e DMA e 2) Em função das intensidades da sinal obtidas por LIBS e DPV. Os resultados obtidos mostram que somente com as variáveis estudadas é possível diferenciar algumas amostras de alfaces proveniente dos três tipos de cultivo. Entretanto, outras alfaces não são bem diferenciadas, pois apresentam certo grau de semelhança na sua composição elementar. Contudo as variáveis estudadas permitirem diferenciar alfaces entre: 1) orgânicas e convencionais, 2) orgânicas e hidropônicas, 3) convencionais e hidropônicas e, 4), considerando as alfaces mais consumidas (crespa, lisa e americana). Na diferenciação de alfaces orgânicas e convencionais, as variáveis utilizadas foram Ca, Mg, K, Mn, Fe e nitrato quando considerados os dados em concentração. Quando somente intensidade de emissão foi empregada, comprimentos de onda referente aos elementos Mg, Mn, B foi empregado, assim como a intensidade de sinal do nitrato.Para a diferenciação entre alfaces orgânicas e hidropônicas as variáveis empregadas foram K, B, Mn e NO 3(concentração) e Mg, B, Mn (intensidade) e nitrato. Na diferenciação entre alfaces convencionais e hidropônicas considerou-se os elementos Ca, B, Mn, Zn e Al (concentração) e Al, B, Fe, Zn, Mn (intensidade). As alfaces mais consumidas oriundas dos 3 tipos de cultivo também foram diferenciadas e as variáveis empregadas foram B, NO, Ca, K e Zn (concentrações) e Mg, B, Mn e NOB3PB (intensidades). Vale destacar que a possibilidade do uso de LIBS+PCA pode resultar no desenvolvimento de método analítico com características… Advisors/Committee Members: Cassiana Seimi Nomura, Ivanise Gaubeur.

Subjects/Keywords: hydroponic; comparison; classification; multi-element analysis; principal component analysis; Hierarchical Cluster Analysis; PCA; HCA; ICP OES, DMA; LIBS, DPV; QUIMICA; alface (Lactuca sativa); composição mineral; orgânico; convencional; hidropônico; comparação; diferenciação; análise multielementar; análise da componente principal; análise da componente hierárquica; PCA: HCA; ICP OES; DMA; LIBS; DPV; Lettuce (Lactuca sativa), mineral composition; organic, conventional

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Martinez, M. I. V. (2011). Discriminação de alface orgânicas e convencionais usando determinação elementar e métodos quimiométricos. (Thesis). Universidade Federal do ABC. Retrieved from http://tede.ufabc.edu.br/tde_busca/arquivo.php?codArquivo=193

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Martinez, Maria Isabel Vega. “Discriminação de alface orgânicas e convencionais usando determinação elementar e métodos quimiométricos.” 2011. Thesis, Universidade Federal do ABC. Accessed July 19, 2019. http://tede.ufabc.edu.br/tde_busca/arquivo.php?codArquivo=193.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Martinez, Maria Isabel Vega. “Discriminação de alface orgânicas e convencionais usando determinação elementar e métodos quimiométricos.” 2011. Web. 19 Jul 2019.

Vancouver:

Martinez MIV. Discriminação de alface orgânicas e convencionais usando determinação elementar e métodos quimiométricos. [Internet] [Thesis]. Universidade Federal do ABC; 2011. [cited 2019 Jul 19]. Available from: http://tede.ufabc.edu.br/tde_busca/arquivo.php?codArquivo=193.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Martinez MIV. Discriminação de alface orgânicas e convencionais usando determinação elementar e métodos quimiométricos. [Thesis]. Universidade Federal do ABC; 2011. Available from: http://tede.ufabc.edu.br/tde_busca/arquivo.php?codArquivo=193

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.