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You searched for subject:(polycrystalline structure). Showing records 1 – 3 of 3 total matches.

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University of Michigan

1. Lita, Adriana Eleni. Correlation between microstructure and surface structure evolution in polycrystalline films.

Degree: PhD, Materials science, 2000, University of Michigan

There is significant interest in the structure of metal thin films due to their wide application as critical components in electronic, magnetic and optical devices. The functionality of these devices is determined by the films physical structure that includes surface morphology and in the case of polycrystalline films, grains size distribution and crystallographic orientation. Many processing schemes have been developed to control film microstructure and surface roughness in practice, however, they usually have limited application related to specific material systems or growth conditions. A comprehensive model for structure development that incorporate deposition conditions and substrate material properties is still lacking. This thesis goal is to further the present understanding on polycrystalline film structure development with an emphasis on the correlation between surface morphology and underlying microstructure evolution. The growth of polycrystalline thin films at different deposition conditions has been explored through a combined characterization of surface structure and underlying microstructure evolution. Both early stage (before and after island coalescence) and later stage evolution (after film continuity) have been studied. Two distinct temporal regimes of film surface evolution: early surface smoothing regime followed by a roughening regime were explained based on the effects of grain growth process during film growth. The microstructure is characterized by development of a crystallographic texture in the initial regime, followed by continued grain growth and an asymptotically increase in the texture component in the later regime. The grain growth process has been identified as a combination of normal and abnormal grain growth mechanisms. Distinct surface morphologies develop during the later growth regime, indicative of different combination of mechanisms acting on specific length scales. The effect of the microstructure on surface morphology has been shown in a study of polycrystalline film evolution on different underlayers. Periodic ridges formed on vicinal Al(111) surfaces corresponding to near-(111) textured grains, and not on exact (111)-oriented grains. Alternatively, the effect of surface structure on the film microstructure has been shown in a study were nucleation of differently oriented grains at the film surface has been correlated with surface roughening during film growth. Advisors/Committee Members: Jr., John E. Sanchez, (advisor).

Subjects/Keywords: Correlation; Crystallographic; Deposition Parameters; Microstructure; Polycrystalline; Structure Evolution; Surface Structure; Thin Films

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APA (6th Edition):

Lita, A. E. (2000). Correlation between microstructure and surface structure evolution in polycrystalline films. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/132620

Chicago Manual of Style (16th Edition):

Lita, Adriana Eleni. “Correlation between microstructure and surface structure evolution in polycrystalline films.” 2000. Doctoral Dissertation, University of Michigan. Accessed April 20, 2021. http://hdl.handle.net/2027.42/132620.

MLA Handbook (7th Edition):

Lita, Adriana Eleni. “Correlation between microstructure and surface structure evolution in polycrystalline films.” 2000. Web. 20 Apr 2021.

Vancouver:

Lita AE. Correlation between microstructure and surface structure evolution in polycrystalline films. [Internet] [Doctoral dissertation]. University of Michigan; 2000. [cited 2021 Apr 20]. Available from: http://hdl.handle.net/2027.42/132620.

Council of Science Editors:

Lita AE. Correlation between microstructure and surface structure evolution in polycrystalline films. [Doctoral Dissertation]. University of Michigan; 2000. Available from: http://hdl.handle.net/2027.42/132620

2. Templin, Brandon Chandler. Towards modeling the anisotropic behavior of polycrystalline materials due to texture using a second order structure tensor.

Degree: PhD, Mechanical Engineering, 2014, Mississippi State University

A material model capable of reproducing the anisotropic behavior of polycrystalline materials will prove to be useful in simulations in which directional properties are of key importance. The primary contributor to anisotropic behavior in polycrystalline materials is the development of texture through the rotation and alignment of slip systems due to plastic deformation. A large concentration of aligned slip systems will influence the glide of dislocations in the respective global deformation direction resulting in a directionally dependent flow stress. The Evolving Microstructural Model of Inelasticity (EMMI) is modified to account for evolving anisotropy due to the development of texture. Texture is characterized via a second order orientation tensor and is incorporated into EMMI through various modifications to the EMMI equations based on physical assumptions. Evolving anisotropy is captured via a static yield surface through a modification to the flow rule based on the assumption loading is entirely elastic within the yield surface. A separate modification to EMMI captures evolving anisotropy through an apparent yield surface via a modification to the EMMI internal state variable evolution equations. The apparent yield surface is the result of a smaller yield surface translating through stress space and assumes the state of the material is disturbed at stresses much lower than indicated by experimental yield surfaces. Advisors/Committee Members: Douglas J. Bammann (chair), Mark F. Horstemeyer (committee member), Youssef Hammi (committee member), Jakob B. Ostien (committee member).

Subjects/Keywords: polycrystalline; texture; orientation distribution function; structure tensor; anisotropy; EMMI

…of a polycrystalline material include grain size and shape, interstitial atoms, cell… …the presented model in future work. 3 1.2 Microstructure Development Polycrystalline… …anisotropic behavior of a polycrystalline aggregate is not effected by the orientation of a single… …x5D;. Processing conditions present in the fabrication of polycrystalline metals can produce… …described as the first to incorporate the 12 FCC slip systems into a polycrystalline 8… 

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

APA (6th Edition):

Templin, B. C. (2014). Towards modeling the anisotropic behavior of polycrystalline materials due to texture using a second order structure tensor. (Doctoral Dissertation). Mississippi State University. Retrieved from http://sun.library.msstate.edu/ETD-db/theses/available/etd-07022014-113740/ ;

Chicago Manual of Style (16th Edition):

Templin, Brandon Chandler. “Towards modeling the anisotropic behavior of polycrystalline materials due to texture using a second order structure tensor.” 2014. Doctoral Dissertation, Mississippi State University. Accessed April 20, 2021. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07022014-113740/ ;.

MLA Handbook (7th Edition):

Templin, Brandon Chandler. “Towards modeling the anisotropic behavior of polycrystalline materials due to texture using a second order structure tensor.” 2014. Web. 20 Apr 2021.

Vancouver:

Templin BC. Towards modeling the anisotropic behavior of polycrystalline materials due to texture using a second order structure tensor. [Internet] [Doctoral dissertation]. Mississippi State University; 2014. [cited 2021 Apr 20]. Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-07022014-113740/ ;.

Council of Science Editors:

Templin BC. Towards modeling the anisotropic behavior of polycrystalline materials due to texture using a second order structure tensor. [Doctoral Dissertation]. Mississippi State University; 2014. Available from: http://sun.library.msstate.edu/ETD-db/theses/available/etd-07022014-113740/ ;

3. Paulson, Noah H. Structure-property linkages for polycrystalline materials using materials knowledge systems.

Degree: PhD, Mechanical Engineering, 2017, Georgia Tech

Computational tools that are capable of rapidly exploring candidate microstructures and their associated properties are required to accelerate the rate of development and deployment of novel materials. In this work, a suite of computationally efficient protocols, based on the materials knowledge system (MKS) framework, are developed to evaluate the properties and performance of polycrystalline microstructures. In the MKS approach, physics-capturing coefficients (calibrated with microstructures and their responses obtained via experiments or simulations) store the microstructure-sensitive response of the material system of interest. Once calibrated, the linkages may be employed to predict the local responses (through localization) or effective properties (through homogenization) of new microstructures at low computational expense. Specifically, protocols are developed to predict bulk properties (elastic stiffness and yield strength), local cyclic plastic strains and resistance to fatigue crack formation and early growth (in the high cycle fatigue and transition fatigue regimes). These protocols are demonstrated on a diverse set of α-titanium microstructures, which exhibit heterogeneous microstructure features, in addition to anisotropy on multiple length-scales. Advisors/Committee Members: Kalidindi, Surya R. (advisor), McDowell, David L. (committee member), Shih, Donald S. (committee member), Neu, Richard W. (committee member), Garmestani, Hamid (committee member).

Subjects/Keywords: Microstructure; Structure-property relationship; Polycrystalline; Titanium alloys; High cycle fatigue; Transition fatigue; Yield strength; Elastic modulus; Data science; Materials informatics; High-throughput; 2-point correlations; Computational model; Crystal plasticity; Reduced-order model; Extreme value statistics

…of transition fatigue performance in polycrystalline microstructures… …Volume Element S-P Structure-Property xii SUMMARY Computational tools that are capable of… …are developed to evaluate the properties and performance of polycrystalline microstructures… …in a reduced-dimensional space using PCA [38]. The structure-property (S-P… …been extended to processing-structure [28–30] and processingstructure-properties… 

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

APA (6th Edition):

Paulson, N. H. (2017). Structure-property linkages for polycrystalline materials using materials knowledge systems. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/60113

Chicago Manual of Style (16th Edition):

Paulson, Noah H. “Structure-property linkages for polycrystalline materials using materials knowledge systems.” 2017. Doctoral Dissertation, Georgia Tech. Accessed April 20, 2021. http://hdl.handle.net/1853/60113.

MLA Handbook (7th Edition):

Paulson, Noah H. “Structure-property linkages for polycrystalline materials using materials knowledge systems.” 2017. Web. 20 Apr 2021.

Vancouver:

Paulson NH. Structure-property linkages for polycrystalline materials using materials knowledge systems. [Internet] [Doctoral dissertation]. Georgia Tech; 2017. [cited 2021 Apr 20]. Available from: http://hdl.handle.net/1853/60113.

Council of Science Editors:

Paulson NH. Structure-property linkages for polycrystalline materials using materials knowledge systems. [Doctoral Dissertation]. Georgia Tech; 2017. Available from: http://hdl.handle.net/1853/60113

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