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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 99 for “"Amorphous phase"”.
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Hardness variation and cyclic crystalline-amorphous phase transformation in CuZr alloy during ball milling
… are measured through several cycles of a cyclic phase transformation during ball milling. Each are found to cycle with a period of approximately 320 minutes. Although significant chemical contamination was found in the milled specimens, the results shed some light on mechanical alloying theory …
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I. The Quantitative X-Ray Determination of Amorphous Phase in Polymers Asrelated to Physical and Chemical Properties. Ii. The Application of Fluorescent X-Ray Spectrometry to Analysis of Hazardous Industrial Dusts
Made available in DSpace on 2014-12-05T19:36:00Z (GMT). No. of bitstreams: 1 0009157.pdf: 3788592 bytes, checksum: 8160fa550b7cc4f45240e2123237749c (MD5) Previous issue date: 1954
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Amorphization and De-vitrification in Immiscible Copper-Niobium Alloy Thin Films
While amorphous phases have been reported in immiscible alloy systems, there is still some controversy regarding the reason for the stabilization of these unusual amorphous phases. Direct evidence of nanoscale phase separation within the amorphous phase forming in immiscible Cu-Nb alloy thin films …
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Hard and tough electrodeposited aluminum-manganese alloys with tailored nanostructures
… regime upon the appearance of a secondary amorphous phase. In these dual-phase alloys, the phases are distributed in a characteristic domain-network structure. At high Mn contents, an amorphous phase that contains pre-existing nanoquasicrystalline nuclei dominates. Leveraging the effects of …
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Solid State Synthesis of Bulk Amorphous Ni – 50AT% Ti Alloy
… pressing (HIP) were used to synthesize bulk amorphous Ni-Ti alloy as an alternative to the traditional methods of casting multi-component metallic alloys. Samples milled cryogenically for 10 hours provided a homogeneous lamella structure with spacing of 30-110 nm. X-ray diffraction and …
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Rekristallisationskinetik von Phasenwechselmedien
Phase change media are tellurium based covalently bonded alloys which exist in a meta-stable amorphous phase at room temperature. Contrary to silicon based semiconductors these materials exhibit a large property contrast between the amorphous and crystalline phase. This is employed for optical and …
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Electrical transport and switching in phase change materials
Phase change materials, typically composed out of Ge, Sb and Te alloys, are materials that can switch very fast between two stable states, the amorphous and the crystalline phase. The optical contrast of the two stable phases led to the application in optical data storage such as compact disks …
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Chalkogenidlegierungen für optische und elektronische Speichermedien
Phasechange alloys are commonly used in optical data storage. Within the next few years an additional application of these alloys is expected to be in solid state memories. In contrast to their widespread use, an understanding of the underlying mechnisms is still incomplete. In this work the …
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Role of nanoscale order in the nucleation of amorphous chalcogenide alloys
Phase change materials, such as Ge2Sb2Te5 (GST), are used as the active recording media in current optical storage and upcoming solid state memories because of their remarkable properties. They can be rapidly and reversibly transformed between the amorphous and crystalline phases, and they exhibit …
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Phase transitions of poly (l-lactic acid) in bulk and in solution
… crystal structures and morphologies during the phase transitions of PLLA in bulk and in solution is pursued in this dissertation. Synchrotron wide- and small-angle x-ray scattering (WAXS and SAXS) are adopted as the primary experimental techniques. Crystallization during annealing and drawing in …
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Electrochemically driven phase transformation in energy storage compounds
… many energy storage compounds undergo phase transitions in-situ, including the production of metastable phases. Unique to this environment is the frequent application of electrical over- and underpotentials, which are the electrical analogs to undercooling and superheating. So far, …
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Understanding of the mechanical response of semicrystalline polymers based on the block-like substructure of crystalline lamellae
… points A and B are mainly due to the crystalline phase representing the coupling and slips of blocks as well as lamellae. 2.the critical strain at C reflects a property of the amorphous phase. It is the maximum elasticity of the ideal semi-crystalline polymer system. At point C, a critical stress …
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Electronic and optical properties of phase change alloys studied with ab initio methods
… electronic and optical properties of so-called phase-change materials is studied. Employing methods of computational physics, in particular density functional theory and many-body perturbation theory this work reveals the correlation between the change of the local atomic structure upon …
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Thermal conductivity anisotropy in molybdenum disulfide thin films
… fully dense solid and 3 times lower than in the amorphous phase. Although thermal conductivity was not strongly dependent on the orientation of the crystal structure, deposition parameters can be used to control thermal conductivity.
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Microstructural analysis of plasticity in low-load contact damage of silicon and germanium
… the plasticity is a result of a ductile metallic phase that forms under the indenter from a pressure-induced metallization of the semiconductor (Mott transition). A metastable amorphous phase is formed when the pressure on the metallic phase drops as the indenter is lifted from the surface. This …
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Crystal-Amorphous Transformation Via Defect-Templating in Phase-Change Materials
Phase-change materials (PCM) such as GeTe and Ge-Sb-Te alloys are potential candidates for non-volatile memory applications, because they can reversibly and rapidly transform between a crystalline phase and an amorphous phase with medium-range order. Traditionally, crystal-amorphous transformation …
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Solvent-Induced Crystallization of Poly(ether ether ketone)
… of poly(ether ether ketone) (PEEK). Unoriented amorphous PEEK films were immersed in aprotic organic liquids at ambient temperature and bulk properties or characteristics were monitored as a function of immersion time. The sorption behavior, Tg and Tm° suppression, crystallinity, and dynamic …
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Copper (I) coordination networks synthesized with solid-solid reactions
… reagents led to crystalline products with no amorphous phase. The nitrogen containing bridging ligands, 4,7-phenanthroline, 4,4'- dipyridyl, and trans-1,2-bis(4-pyridy1)ethylene in addition to 1,3-dithiane were used in the formation of these networks. The resultant crystalline compounds were …
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Fundamental studies on ionomer glasses
… the glass transition temperature resulted in amorphous phase separation, probably by a spinodal decomposition mechanism, followed by a two stage crystallization of calcium fluoride (fluorite) and anorthite. The anorthite phase crystallized from fluorite nuclei and, in effect, crystallization …
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Fundamental Understanding and Functionality of Silicon Oxycarbide
… oxygen, and carbon atoms in the form of an amorphous network structure. The phase separation of SiOC is determined by polymeric precursors, pyrolysis temperatures, and atmosphere, which results in different compositions and microstructures. Because of its unique properties (high thermal …
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