Theoretical and experimental studies of grain boundary structures were carried out to understand the grain boundary properties of Ni₃Al. Using various techniques of transmission electron microscopy, the geometry of grain boundaries was determined from a number of grain boundaries to obtain a distribution of grain boundary types in Ni₃Al. Five macroscopic parameters, including a misorientation between two grains and a grain boundary plane orientation, were considered in the grain boundary type. A distribution of grain boundary types in ductile Ni₃Al contained more low Σ boundaries than brittle Ni₃Al. In a distribution of grain boundary plane orientations, the trend of having high density plane of coincident sites was maintained on low Σ boundaries up to Σ = 9 and random orientations of grain boundary planes became dominant after Σ = 11. In ductile Ni₃Al, grain boundary accommodations of dislocations in the vicinity of grain boundaries were found, which were not shown in brittle Ni₃Al. Using CBED techniques, symmetry information of a single crystal was obtained. However, an extension to bicrystals was not successful. In order to study the possible disordering and segregation near grain boundaries, two different atomistic computer simulations, namely, molecular statics simulation and two dimensional lattice gas model, were carried out. Both results showed a similar trend of disordering near the grain boundary regardless of grain boundary composition and atomic interaction energy assumptions. However, segregation behavior near grain boundaries showed strong influences from grain boundary compositions and atomic interaction energy assumptions. / Ph. D.

A diversity of facets in the relationships between gender and space in Jordan come to light throughout this study, highlighting foremost the contentious nature running throughout the relationships between men and women as each gender attempts to shape, expand, and solidify the accepted gender roles and realms of influence within society. The study also exposes the power of issues like assumption, perception, reputation, and religious or cultural fervor in relation to discerning whether men and women can reside in or at least share the same space or whether the tensions between the genders are so great that men and women are foes who cannot peacefully cross the boundaries between spaces. For further insight into this topic of genderized space allocation, boundary maintenance, and power distribution in Jordan, the examination of the relationships between gender and space through the political, economic, educational, religious, and cultural lenses of Jordanian society offers documentation, in powerful terms and images, of the ways each element of society "political, economic, educational, religious, and cultural" supports the idea of fluidity in the boundaries between genderized public and private spaces but, paradoxically, provides even more efficient tools for increasing the rigidity and divisiveness of those same boundaries. Consequently, genders in Jordan remain divided between public and private spaces — a social reality shaped, supported, and enhanced by the interaction between both qualitative, emotion-based elements and tangible, fact-based elements. / Master of Arts

A theoretical and experimental study of Grain boundary structure in B doped Ni₃Al was carried out. Geometrical modelling was done to obtain the grain boundary structure in Ll₂ compounds for different misorientations between two grains. The size of interstitial sites in these boundaries was calculated to understand the segregation of B to the boundaries. Ratios of the B-B equilibrium interatomic distance to the nearest neighbour distances in various (A₃B) Ll₂ compounds were calculated, in an attempt to predict the grain boundary fracture behaviour in these compounds. Selected area channeling patterns were obtained from a number of grains to solve for the orientation relationship between grains, in order to predict the structure of the boundaries between them. A distribution of grain boundary structure that is different from the distribution for an undoped Ni₃Al is obtained in this work and is compared with results from other investigators. / M.S.

not OCRd / Master of Science

In an effort to understand intrinsic grain boundary brittleness, computer simulation of grain boundary structures in ordered NiAl was carried out. The considered boundaries were boundaries of low reciprocal coincident site density Σ. The structural unit model was used to obtain a general picture of the grain boundary features in NiAl. Relation between the grain boundary stoichiometry and the energy was studied and it was found that the grain boundary energy increases with a higher aluminum content in the grain boundary. Thus, excess of aluminum in the grain boundary seems to make the material brittle. The grain boundaries obtained are relatively dense and grain boundary brittleness would not be expected to originate from large interstitial holes. However, the structures computed show a large spread in energy values and it is proposed that the observed brittleness is due to the appearance of high energy structures when dislocations arrive at the boundary. / Master of Science

No description available.

Depuis des décennies, le rôle joué par les joints de grains dans le comportement plastique des matériaux cristallins interroge mécaniciens, métallurgistes, spécialistes des matériaux. Après les avancées décisives de la plasticité individuelle des cristaux et de leur comportement collectif au sein d’agrégats, les effets complexes des interfaces sur le comportement effectif constituent l’enjeu restant à maîtriser. Car si les joints peuvent aussi bien être sites d’endommagement que réseau de consolidation dans une structure polycristalline, ils contribuent toujours fortement aux propriétés macroscopiques de cette dernière. Le travail réalisé est une contribution à l’étude du comportement des joints lors de traitements thermomécaniques induisant leur mobilité. On parle de migration.Nous avons étudié les caractéristiques essentielles de la migration de joints de grains à partir du mécanisme de SIBM (croissance de grains sans germination après faible déformation plastique). La migration des joints de grains sous recuit après déformation a été suivie in situ en MEB. Les évolutions microstructurales sont analysées en MEB et en AFM. Les principales forces et caractéristiques contribuant à la migration des joints sont étudiées. Pour les forces, un diagramme de migration reliant le déplacement des joints à l’énergie de courbure et à l’énergie stockée par déformation plastique a permis d’évaluer la pertinence de l’expression usuelle de la force motrice de migration et d’en discuter de possibles ajustements. Pour les caractéristiques, nous avons confirmé l’effet de surface de la gravure thermique et celui plus intrinsèque des jonctions triples sur la mobilité des joints de grains. / For many decades, the role of grain boundaries in the plastic behavior of crystalline materials questions engineers, metallurgists, materials scientists. After the decisive progress in plasticity of individual crystals and for their collective behavior in aggregates, the complex effects of boundaries on the actual behavior are the remaining challenge to master. If boundaries can as well be considered as damage sites as strengthening network in a poly-crystalline structure, they always contribute greatly to the macroscopic properties of the latter. This work is a contribution to the study of the behavior of boundaries during thermomechanical treatments inducing mobility. We talk about migration.We studied the essential characteristics of the migration of grain boundaries from SIBM mechanism (Strain Induced Boundary Migration). The migration of grain boundaries under annealing after deformation was monitored in situ SEM. Microstructural changes are analyzed by SEM and AFM. The main strengths and characteristics contributing to the boundary migration are studied. For strengths, a migration diagram linking the displacements of grain boundaries to the curvature energy and the stored energy from plastic deformation allowed to assessing of the relevance of the usual expression for the migration driving force and to discussing possible adjustments. For characteristics, we confirmed the surface effect of the thermal grooving and the more intrinsic one of triple junctions on the mobility of grain boundaries.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 125-136). Also available on the World Wide Web.

The 21st-century climate crisis and human development are placing a burden on the planet and society and require strategic integration as well as education about sustainable development. Universities are educational institutions and have the potential to encourage and empower a climate-friendly individual and collective behaviours and educate about the importance of sustainable development pathways that are grounded in social and planetary long-term goals. This thesis departs from the challenge to create a joint holistic understanding of sustainability and the concept of sustainable development among universities and their strategies and development plans for the future. It aims to examine the integration of social and planetary boundaries within university strategies and what enables as well as hinders sustainable development engagement. Accordingly, this study builds on a comparative analysis using document analysis of strategic documents from seven different European universities which were complemented by seven expert interviews. The social and planetary boundaries set the analytical framework. This study finds that university strategies are recognising and addressing sustainable development within their course of action but there is no common standard on how and to what extent this has to be addressed and barriers prevent an even stronger commitment. Furthermore, an indicated gap between envisioning goals and acting upon them raises the question of to what extent strategy documents are just used as marketing tools. The study concludes by proposing a framework which depicts the baseline requirements that all universities should fulfil in terms of sustainable development engagement and implementation measures.

In its recent surge in popularity, Kate Raworth's Doughnut Economics has garnered significant attention and has been applied on a global, national, and local scale. However, its implementation within organizational settings has yet to be adopted, despite evident interest. This paper delves into the potential application of the Doughnut Model (DM) within an enterprise context, examining both its strengths and limitations stemming from its core structure and principles, as well as the complexities of enterprise environments. By conducting interviews with Länsförsäkringar and another insurance company, this paper seeks to interpret the advantages and limitations of integrating the DM into organizational frameworks. Qualitative research methods, including interviews with sustainability managers, asset managers, and business development managers, were employed to gather diverse insights from industry professionals. Additionally, interviews with professors were conducted to gain deeper insights into the model's structure and foundational principles. Through qualitative thematic analysis, various advantages and limitations were uncovered. Advantages primarily revolved around visual representation, business strategy, grasping sustainability, inclusiveness, business transparency, comparability, regulations, and awareness. Identified limitations brought into question certain aspects of DE. These limitations included critiques of its principle's negative stance on GDP growth, challenges to its Western-centric ideology, and its oversight of altruistic social behaviors. Furthermore, concerns were raised regarding its historical and perceptual context, which could potentially mislead due to its anthropocentric characteristics and compartmentalized framing. Moreover, challenges in applying the model to enterprises were identified, such as external pressures to comply with upcoming regulations, resource constraints, financial limitations, and the overarching imperative of ensuring the company's survival. The absence of software tools and clear instructions on measuring all indicators further complicates implementation, highlighting the need for additional research in this area. It is recommended that future studies focus on developing guidelines for firms to address all boundaries effectively, offering pragmatic approaches for integration in operations.