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Description
Aluminum alloys and their composites are attractive materials for applications requiring high strength-to-weight ratios and reasonable cost. Many of these applications, such as those in the aerospace industry, undergo fatigue loading. An understanding of the microstructural damage that occurs in these materials is critical in assessing their fatigue resistance. Two distinct experimental studies were performed to further the understanding of fatigue damage mechanisms in aluminum alloys and their composites, specifically fracture and plasticity. Fatigue resistance of metal matrix composites (MMCs) depends on many aspects of composite microstructure. Fatigue crack growth behavior is particularly dependent on the reinforcement characteristics and matrix microstructure. The goal of this work was to obtain a fundamental understanding of fatigue crack growth behavior in SiC particle-reinforced 2080 Al alloy composites. In situ X-ray synchrotron tomography was performed on two samples at low (R=0.1) and at high (R=0.6) R-ratios. The resulting reconstructed images were used to obtain three-dimensional (3D) rendering of the particles and fatigue crack. Behaviors of the particles and crack, as well as their interaction, were analyzed and quantified. Four-dimensional (4D) visual representations were constructed to aid in the overall understanding of damage evolution. During fatigue crack growth in ductile materials, a plastic zone is created in the region surrounding the crack tip. Knowledge of the plastic zone is important for the understanding of fatigue crack formation as well as subsequent growth behavior. The goal of this work was to quantify the 3D size and shape of the plastic zone in 7075 Al alloys. X-ray synchrotron tomography and Laue microdiffraction were used to non-destructively characterize the volume surrounding a fatigue crack tip. The precise 3D crack profile was segmented from the reconstructed tomography data. Depth-resolved Laue patterns were obtained using differential-aperture X-ray structural microscopy (DAXM), from which peak-broadening characteristics were quantified. Plasticity, as determined by the broadening of diffracted peaks, was mapped in 3D. Two-dimensional (2D) maps of plasticity were directly compared to the corresponding tomography slices. A 3D representation of the plastic zone surrounding the fatigue crack was generated by superimposing the mapped plasticity on the 3D crack profile.
ContributorsHruby, Peter (Author) / Chawla, Nikhilesh (Thesis advisor) / Solanki, Kiran (Committee member) / Liu, Yongming (Committee member) / Arizona State University (Publisher)
Created2014
Description
Western landscape photography helped to create an imaginative perception of a new nation for Americans. Early nineteenth-century photographers captured a vision of uncharted terrain that metaphorically fulfilled a two-fold illusion: an untouched Eden and a land ready and waiting for white settlement. The sublime and picturesque experiences of the West provided artists a concept that could be capitalized upon by employing various forms of manipulation. In the twentieth-century, the role of landscape photography evolved as did the advancement of the West. Images of wilderness became art and photographers chose to view the western landscape differently. Some focused more sharply and critically on the relationship between the land and the people who lived on it. The influential exhibition in 1975, New Topographics: Photographs of a Man-altered Landscape presented work that showed a landscape altered, marked by power lines, houses, and fences. The West as Eden no longer existed. Today, photographers continue to examine, image, and experience western land anew. In this thesis I examine the relationship of contemporary landscape photography and the role of the West, guided by an analysis that traces the history of American ideologies and attitudes toward natural land. The artists I have chosen recognize landscape not as scenery but as the spaces and systems people inhabit, and use manipulative strategies that emphasize an artificial character of the West. Their work elicits antecedent mythologies, pictorial models, and American ideologies that continue to perpetuate internationally.
ContributorsHerden, Nicole (Author) / Fahlman, Betsy (Thesis advisor) / Serwint, Nancy (Committee member) / Klett, Mark (Committee member) / Arizona State University (Publisher)
Created2013
Description
The history of jade in many ways reflects the evolution of Chinese civilization, encompassing its entire history and geographical extent and the many cultural traditions associated with the various regions that have finally been brought together in the unity of present-day China. The archaic jade collections investigated in this thesis, from an archaeological point of view, primarily consist of pieces from the late Neolithic through early historic era, named the "Jade Age" by academics. Although well-researched museum catalogues of archaic Chinese jades have been widely published by major museums in the United States, they are mostly single collection oriented. It is, then, necessary to conduct research examining the overall picture of collecting practices in the U.S. Given the proliferation of fake early jades, this study will provide an essential academic reference for researchers, students, and the present art market. This thesis seeks to explore how shifting tastes, political climates, and personal ambitions, as well as various opportunities and personalities, were instrumental factors in shaping these important collections of archaic Chinese jades in the U.S. today.
ContributorsWang, Yijing (Author) / Brown, Claudia (Thesis advisor) / Fahlman, Betsy (Committee member) / Baker, Janet (Committee member) / Schleif, Corine (Committee member) / Arizona State University (Publisher)
Created2014
Description
Concrete is the most widely used infrastructure material worldwide. Production of portland cement, the main binding component in concrete, has been shown to require significant energy and account for approximately 5-7% of global carbon dioxide production. The expected continued increased use of concrete over the coming decades indicates this is an ideal time to implement sustainable binder technologies. The current work aims to explore enhanced sustainability concretes, primarily in the context of limestone and flow. Aspects such as hydration kinetics, hydration product formation and pore structure add to the understanding of the strength development and potential durability characteristics of these binder systems. Two main strategies for enhancing this sustainability are explored in this work: (i) the use of high volume limestone in combination with other alternative cementitious materials to decrease the portland cement quantity in concrete and (ii) the use of geopolymers as the binder phase in concrete. The first phase of the work investigates the use of fine limestone as cement replacement from the perspective of hydration, strength development, and pore structure. The nature of the potential synergistic benefit of limestone and alumina will be explored. The second phase will focus on the rheological characterization of these materials in the fresh state, as well as a more general investigation of the rheological characterization of suspensions. The results of this work indicate several key ideas. (i) There is a potential synergistic benefit for strength, hydration, and pore structure by using alumina and in portland limestone cements, (ii) the limestone in these systems is shown to react to some extent, and fine limestone is shown to accelerate hydration, (iii) rheological characteristics of cementitious suspensions are complex, and strongly dependent on several key parameters including: the solid loading, interparticle forces, surface area of the particles present, particle size distribution of the particles, and rheological nature of the media in which the particles are suspended, and (iv) stress plateau method is proposed for the determination of rheological properties of concentrated suspensions, as it more accurately predicts apparent yield stress and is shown to correlate well with other viscoelastic properties of the suspensions.
ContributorsVance, Kirk (Author) / Neithalath, Narayanan (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Mobasher, Barzin (Committee member) / Chawla, Nikhilesh (Committee member) / Marzke, Robert (Committee member) / Arizona State University (Publisher)
Created2014
Description
For decades, microelectronics manufacturing has been concerned with failures related to electromigration phenomena in conductors experiencing high current densities. The influence of interconnect microstructure on device failures related to electromigration in BGA and flip chip solder interconnects has become a significant interest with reduced individual solder interconnect volumes. A survey indicates that x-ray computed micro-tomography (µXCT) is an emerging, novel means for characterizing the microstructures' role in governing electromigration failures. This work details the design and construction of a lab-scale µXCT system to characterize electromigration in the Sn-0.7Cu lead-free solder system by leveraging in situ imaging.
In order to enhance the attenuation contrast observed in multi-phase material systems, a modeling approach has been developed to predict settings for the controllable imaging parameters which yield relatively high detection rates over the range of x-ray energies for which maximum attenuation contrast is expected in the polychromatic x-ray imaging system. In order to develop this predictive tool, a model has been constructed for the Bremsstrahlung spectrum of an x-ray tube, and calculations for the detector's efficiency over the relevant range of x-ray energies have been made, and the product of emitted and detected spectra has been used to calculate the effective x-ray imaging spectrum. An approach has also been established for filtering `zinger' noise in x-ray radiographs, which has proven problematic at high x-ray energies used for solder imaging. The performance of this filter has been compared with a known existing method and the results indicate a significant increase in the accuracy of zinger filtered radiographs.
The obtained results indicate the conception of a powerful means for the study of failure causing processes in solder systems used as interconnects in microelectronic packaging devices. These results include the volumetric quantification of parameters which are indicative of both electromigration tolerance of solders and the dominant mechanisms for atomic migration in response to current stressing. This work is aimed to further the community's understanding of failure-causing electromigration processes in industrially relevant material systems for microelectronic interconnect applications and to advance the capability of available characterization techniques for their interrogation.
In order to enhance the attenuation contrast observed in multi-phase material systems, a modeling approach has been developed to predict settings for the controllable imaging parameters which yield relatively high detection rates over the range of x-ray energies for which maximum attenuation contrast is expected in the polychromatic x-ray imaging system. In order to develop this predictive tool, a model has been constructed for the Bremsstrahlung spectrum of an x-ray tube, and calculations for the detector's efficiency over the relevant range of x-ray energies have been made, and the product of emitted and detected spectra has been used to calculate the effective x-ray imaging spectrum. An approach has also been established for filtering `zinger' noise in x-ray radiographs, which has proven problematic at high x-ray energies used for solder imaging. The performance of this filter has been compared with a known existing method and the results indicate a significant increase in the accuracy of zinger filtered radiographs.
The obtained results indicate the conception of a powerful means for the study of failure causing processes in solder systems used as interconnects in microelectronic packaging devices. These results include the volumetric quantification of parameters which are indicative of both electromigration tolerance of solders and the dominant mechanisms for atomic migration in response to current stressing. This work is aimed to further the community's understanding of failure-causing electromigration processes in industrially relevant material systems for microelectronic interconnect applications and to advance the capability of available characterization techniques for their interrogation.
ContributorsMertens, James Charles Edwin (Author) / Chawla, Nikhilesh (Thesis advisor) / Alford, Terry (Committee member) / Jiao, Yang (Committee member) / Neithalath, Narayanan (Committee member) / Arizona State University (Publisher)
Created2015
Description
In this thesis, I investigate the anatomical excesses represented in the works of Jean-Auguste-Dominique Ingres. In recent years, art historical scholarship on Ingres has multiplied after being quiescent for much of the twentieth century, as contemporary scholars perceive the unusual contradictions in his works. I introduce the concepts of pathological versus imaginary distortions. Pathological distortions are distortions that represent diseased bodies, such as the goiters in many of Ingres's female figures, whereas imaginary distortions are not anatomically possible, such as the five extra vertebrae in the Grande Odalisque. Ingres employed both of these types of these distortions in his bodies, and I discuss how these two types of distortions can be read differently.
My thesis is that Ingres employed extended anatomical variations-in his paintings, most notably in his female figures, for several reasons: to reconcile his anxiety about originality while remaining within the tradition of Classicism and "disegno," to pay homage to his predecessors who were also the masters of line, and to highlight his command of line and drawing. Though Ingres has never been a strictly Neoclassical artist in the Davidian tradition, the Romantic elements of his work are underlined further by these anatomical variations.
My thesis is that Ingres employed extended anatomical variations-in his paintings, most notably in his female figures, for several reasons: to reconcile his anxiety about originality while remaining within the tradition of Classicism and "disegno," to pay homage to his predecessors who were also the masters of line, and to highlight his command of line and drawing. Though Ingres has never been a strictly Neoclassical artist in the Davidian tradition, the Romantic elements of his work are underlined further by these anatomical variations.
ContributorsEpstein, Danya (Author) / Codell, Julie F. (Thesis advisor) / Gully, Anthony (Committee member) / Fahlman, Betsy (Committee member) / Arizona State University (Publisher)
Created2015
Description
The turmoil that China endured during the twentieth century triggered a series of social and political revolutions. As China struggled to resolve domestic questions of dynasticism or democracy and nationalism or communism, Western industrialization and imperialism dragged China rapidly into the globalizing world. Likewise, Chinese painting had to confront the West, as Chinese artists dealt with the twentieth-century version of the recurring question of modernizing Chinese painting for its times: how does one reconcile an ancient painting tradition with all the possibilities Western interactions introduced? This dissertation focuses on one artist's lifelong struggle, often overlooked, to answer this question. By examining C. C. Wang (1907-2003) and his life in art, this case study reveals broader truths about how twentieth century Chinese diaspora painters, such as Wang, modernized the tradition of Chinese ink painting.
Wang's reputation as a connoisseur of ancient Chinese painting has overshadowed his own artwork, creating a dearth of research on his artistic development. Using public and private sources, this dissertation applied stylistic analysis to track this development. The analysis reveals an artist's lifelong endeavor to establish a style that would lift the Chinese painting tradition into a modern era, an endeavor inspired by modern Western art ideas and a desire to play a role in the larger movement of elevating Chinese painting. The argument is made that these efforts establish Wang as an influential twentieth century Chinese ink painter.
To clarify Wang's role within the broader movement of Chinese diaspora painters, this dissertation employs a comparison study of Wang with such established twentieth century ink painting artists as Zhang Daqian, Liu Guosong, and Yu Chengyao. It is
asserted that the 1949 diaspora forced this cohort of artists to adjust their style and to transcend traditional Chinese painting by integrating newly-salient ideas from Western art, particularly the abstract movement. Meanwhile, the essential Chinese identity in their art collectively became more significant. The solidarity of purpose and identity is a distinctive part of the answer this group of twentieth century Chinese diaspora painters proposed to their generation's inherited challenge of enriching the tradition.
Wang's reputation as a connoisseur of ancient Chinese painting has overshadowed his own artwork, creating a dearth of research on his artistic development. Using public and private sources, this dissertation applied stylistic analysis to track this development. The analysis reveals an artist's lifelong endeavor to establish a style that would lift the Chinese painting tradition into a modern era, an endeavor inspired by modern Western art ideas and a desire to play a role in the larger movement of elevating Chinese painting. The argument is made that these efforts establish Wang as an influential twentieth century Chinese ink painter.
To clarify Wang's role within the broader movement of Chinese diaspora painters, this dissertation employs a comparison study of Wang with such established twentieth century ink painting artists as Zhang Daqian, Liu Guosong, and Yu Chengyao. It is
asserted that the 1949 diaspora forced this cohort of artists to adjust their style and to transcend traditional Chinese painting by integrating newly-salient ideas from Western art, particularly the abstract movement. Meanwhile, the essential Chinese identity in their art collectively became more significant. The solidarity of purpose and identity is a distinctive part of the answer this group of twentieth century Chinese diaspora painters proposed to their generation's inherited challenge of enriching the tradition.
ContributorsHua, Ming (Author) / Brown, Claudia (Thesis advisor) / Baker, Janet (Committee member) / Fahlman, Betsy (Committee member) / Arizona State University (Publisher)
Created2014
Description
As one of the most promising materials for high capacity electrode in next generation of lithium ion batteries, silicon has attracted a great deal of attention in recent years. Advanced characterization techniques and atomic simulations helped to depict that the lithiation/delithiation of silicon electrode involves processes including large volume change (anisotropic for the initial lithiation of crystal silicon), plastic flow or softening of material dependent on composition, electrochemically driven phase transformation between solid states, anisotropic or isotropic migration of atomic sharp interface, and mass diffusion of lithium atoms. Motivated by the promising prospect of the application and underlying interesting physics, mechanics coupled with multi-physics of silicon electrodes in lithium ion batteries is studied in this dissertation. For silicon electrodes with large size, diffusion controlled kinetics is assumed, and the coupled large deformation and mass transportation is studied. For crystal silicon with small size, interface controlled kinetics is assumed, and anisotropic interface reaction is studied, with a geometry design principle proposed. As a preliminary experimental validation, enhanced lithiation and fracture behavior of silicon pillars via atomic layer coatings and geometry design is studied, with results supporting the geometry design principle we proposed based on our simulations. Through the work documented here, a consistent description and understanding of the behavior of silicon electrode is given at continuum level and some insights for the future development of the silicon electrode are provided.
ContributorsAn, Yonghao (Author) / Jiang, Hanqing (Thesis advisor) / Chawla, Nikhilesh (Committee member) / Phelan, Patrick (Committee member) / Wang, Yinming (Committee member) / Yu, Hongyu (Committee member) / Arizona State University (Publisher)
Created2014
Description
Increasing demand for high strength powder metallurgy (PM) steels has resulted in the development of dual phase PM steels. In this work, the effects of thermal aging on the microstructure and mechanical behavior of dual phase precipitation hardened powder metallurgy (PM) stainless steels of varying ferrite-martensite content were examined. Quantitative analyses of the inherent porosity and phase fractions were conducted on the steels and no significant differences were noted with respect to aging temperature. Tensile strength, yield strength, and elongation to fracture all increased with increasing aging temperature reaching maxima at 538oC in most cases. Increased strength and decreased ductility were observed in steels of higher martensite content. Nanoindentation of the individual microconstituents was employed to obtain a fundamental understanding of the strengthening contributions. Both the ferrite and martensite hardness values increased with aging temperature and exhibited similar maxima to the bulk tensile properties. Due to the complex non-uniform stresses and strains associated with conventional nanoindentation, micropillar compression has become an attractive method to probe local mechanical behavior while limiting strain gradients and contributions from surrounding features. In this study, micropillars of ferrite and martensite were fabricated by focused ion beam (FIB) milling of dual phase precipitation hardened powder metallurgy (PM) stainless steels. Compression testing was conducted using a nanoindenter equipped with a flat punch indenter. The stress-strain curves of the individual microconstituents were calculated from the load-displacement curves less the extraneous displacements of the system. Using a rule of mixtures approach in conjunction with porosity corrections, the mechanical properties of ferrite and martensite were combined for comparison to tensile tests of the bulk material, and reasonable agreement was found for the ultimate tensile strength. Micropillar compression experiments of both as sintered and thermally aged material allowed for investigation of the effect of thermal aging.
ContributorsStewart, Jennifer (Author) / Chawla, Nikhilesh (Thesis advisor) / Jiang, Hanqing (Committee member) / Krause, Stephen (Committee member) / Arizona State University (Publisher)
Created2011
Description
The mechanical behavior of Pb-free solder alloys is important, since they must maintain mechanical integrity under thermomechanical fatigue, creep, and mechanical shock conditions. Mechanical shock, in particular, has become an increasing concern in the electronics industry, since electronic packages can be subjected to mechanical shock by mishandling during manufacture or by accidental dropping. In this study, the mechanical shock behavior of Sn and Sn-Ag-Cu alloys was systematically analyzed over the strain rate range 10-3 - 30 s-1 in bulk samples, and over 10-3 - 12 s-1 on the single solder joint level. More importantly, the influences of solder microstructure and intermetallic compounds (IMC) on mechanical shock resistance were quantified. A thorough microstructural characterization of Sn-rich alloys was conducted using synchrotron x-ray computed tomography. The three-dimensional morphology and distribution of contiguous phases and precipitates was analyzed. A multiscale approach was utilized to characterize Sn-rich phases on the microscale with x-ray tomography and focused ion beam tomography to characterize nanoscale precipitates. A high strain rate servohydraulic test system was developed in conjunction with a modified tensile specimen geometry and a high speed camera for quantifying deformation. The effect of microstructure and applied strain rate on the local strain and strain rate distributions were quantified using digital image correlation. Necking behavior was analyzed using a novel mirror fixture, and the triaxial stresses associated with necking were corrected using a self-consistent method to obtain the true stress-true strain constitutive behavior. Fracture mechanisms were quantified as a function of strain rate. Finally, the relationship between solder microstructure and intermetallic compound layer thickness with the mechanical shock resistance of Sn-3.8Ag-0.7Cu solder joints was characterized. It was found that at low strain rates the dynamic solder joint strength was controlled by the solder microstructure, while at high strain rates it was controlled by the IMC layer. The influences of solder microstructure and IMC layer thickness were then isolated using extended reflow or isothermal aging treatments. It was found that at large IMC layer thicknesses the trend described above does not hold true. The fracture mechanisms associated with the dynamic solder joint strength regimes were analyzed.
ContributorsYazzie, Kyle (Author) / Chawla, Nikhilesh (Thesis advisor) / Sane, Sandeep (Committee member) / Jiang, Hanqing (Committee member) / Krause, Stephen (Committee member) / Arizona State University (Publisher)
Created2012