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Experimentální studium ultrajemnozrnných slitin Ti pro využití v biomedicíně
Václavová, Kristína ; Stráský, Josef (advisor) ; Šíma, Vladimír (referee)
In the present work the microstructure evolution of Ti-6Al-7Nb alloy prepared by high pressure torsion (HPT) and equal channel angular pressing (ECAP) was studied by scanning electron microscopy, microhardness measurements and electrical resistance measurements. Electron microscopy showed a bimodal structure of the alloy and deformed structure after HPT. Microhardness increased with the increasing number of turns of high pressure torsion. Electron back-scattered diffraction figured out that the grain misorientations are not random. Changes in the electrical resistance of the alloy prepared by ECAP showed irreversible process after heating above 450řC.
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Fázové transformace a mikrostrukturní změny ve slitině TIMET LCB
Šmilauerová, Jana ; Janeček, Miloš (advisor) ; Šíma, Vladimír (referee)
In the present work, phase transformations in TIMETAL LCB tita- nium alloy and their influence on mechanical properties were studied. Different initial conditions were prepared by solution treating above β-transus immedi- ately followed by heat treatment in α/β temperature regime. These resulted in different grain boundary α thicknesses and contiguities at a fixed α vol- ume fraction. The subsequent ageing response of this material was studied by low temperature ageing at 400 ◦ C, 450 ◦ C and 500 ◦ C. Phase transformations were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and resistivity measurements. Mechan- ical properties were investigated using microhardness measurements and tensile tests. It has been proved that metastable ω phase is formed during annealing at 400 ◦ C and 450 ◦ C. ω particles further transform to very fine precipitates of α phase when exposed to annealing for longer time periods. These fine precip- itates significantly contribute to increase of microhardness and achieving high value of yield stress. Keywords: Metastable beta Ti alloys, phase transformations, microstructure changes, ω phase 1
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Diffusion of native defects and impurities in CdTe/CdZnTe
Šedivý, Lukáš ; Belas, Eduard (advisor) ; Šíma, Vladimír (referee)
Title: Diffusion of native defects and impurities in CdTe/CdZnTe. Author: Lukáš Šedivý Author's e-mail address: luky.sedivy@seznam.cz Department: Institute of Physics of Charles University Supervisor: Doc. Ing. Eduard Belas, CSc. Supervisor's e-mail address: belas@karlov.mff.cuni.cz Abstract: In this thesis, the influence of structural defects on the electrical and de- tection characteristics of CdTe material was investigated. The performed research fo- cused on the reduction of structural defects in the material by annealing in Cd or Te vapor, while preserving acceptable features for X-ray and γ-ray detection. The mate- rial was characterized by measurement of the electrical resistivity and concentration and mobility of free carriers. Tellurium and cadmium inclusions were studied using infrared microscope. The static and dynamic properties of defect structures at high temperatures and de- fined Cd pressures was investigated, as well, and chemical diffusion coeficients describing the dynamic properties of these defects were experimentally determined. Keywords: monocrystal CdTe, structural defects in semiconductors, annealing in Cd or Te, chemical diffusion coefficient, γ-ray detectors. 1
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The spatial surveyedof the historic object
ŠÍMA, Vladimír
The purpose of this bachelor works is the spatial surveyed of the historic object. The Chapel of sv. Vojtěch is selected object. This chapel is situated in Husova třída in the České Budějovice. The first part of this bachelor works is described the history of the object, preparatory works for the surveyed historical object (field reconnaissance, options of surveying the network) and subsequently used surveying methods which are detailed. In the second part there is described process of the creation of 3D model. Here are described the methods, software which are used to create 3D model and resulting utilization.
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