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Introspection
Buzková, Petra ; Zálešák, Jan (referee) ; Kvíčala, Petr (advisor)
The main theme of my work is introspection. I watch their perceptions with which the work in pictures. Feelings are based on the most intense experiences of the landscape that makes you aware of herself and time, whether it is the past and its memories or related to the presence and subsequent future. These dimensions of time and awareness of their role in it processed in a larger format paintings, which is represented in the landscape, figure, or a fragment thereof and an artifact that link to memories of childhood. Furthermore, I come from the ideas of Thomas Moore contained in the Book of the soul with which I agree. In small format displays philosophical and psychological ideas of the author, based on generally accepted theories of human psychology. Moore Certain considerations addressed in the analysis of the images of themselves, but they are also generally applicable. Processing internal processes so that the audience for them to install their own.
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Tvorba WWW prezentace pro autonomního robota
Zálešák, Jan
This bachelor's thesis deals with designing and production of web application for presentation of panoramic photographs of Mendel university arboretum in Brno. Taking photographs is temporarily substituted by hand-operated camera until autonomous robot is completely functional. This thesis covers particular de-scription of used technologies and procedures of application. The result is detailed instruction manual of application and its economic evaluation.
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Analytical electron microscopy of lead-free nanopowder solders
Buršík, Jiří ; Sopoušek, J. ; Zálešák, Jakub ; Buršíková, V.
During the last decade, the EU legislative regulations enforced lead-free solders and hence initiated an extensive search for the best replacement of lead-containing solders. Parallel to new binary and ternary bulk solders, metal nanoparticles are also considered as potential candidates for solder materials. It is known that physical, electric and thermodynamic properties of nanoobjects are significantly different from those of the bulk materials. The oxidation, high reactivity of the surfaces and aggregation are frequent problems of nanotechnology applications. The nanoparticles of pure metals and alloys exhibit the depression of the melting point compared to bulk material, hence they are able to aggregate and to form firm interlayer joints at low temperatures. Exploiting this effect can save energy, work and materials.
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NANOSTRUCTURE CHARACTERIZATION OF IN738LC SUPERALLOY FATIGUED AT HIGH TEMPERATURE
Petrenec, M. ; Strunz, Pavel ; Gasser, U. ; Heczko, Milan ; Zálešák, J. ; Polák, Jaroslav
The nanostructure of Inconel 738LC Ni-superalloy strengthened by trimodal Y precipitates distribution was investigated after Low Cycle Fatigue (LFC) loading at temperature 700°C. Different microscopic techniques as Scanning Electron Microscope (SEM) equipped with STEM detectro, transmission Kikuchi diffraction in the SEM, transmission electron microscope (TEM) in the bright field mode and high resolution transmission electron mciroscopes (HRTEM) in STEM mode were used for the characterization and quantification of superalloy nanostructure. The characteristic morphology of y precipitates was examined by ex-situ and in-situ Small Angle Neutron Scattering (SANS) at high temperatures. All adopted microscopic techniques indicate that the morphology of y precipitates distributed in the y matrix as recived state corresponds to two types, i.e. large cuboid-like precipitates with the size around 670 nm, and the spherical precipitates with the diameter 52nm. After eh LCF tests at temperature 700°C, the ex-situ SANS measurement yielded addititonal scattering intensities coming from another small y precipitetes with estimated size up to 10nm.
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NANOSTRUCTURE CHARACTERIZATION OF IN738LC SUPERALLOY FATIGUED AT HIGH TEMPERATURE
Petrenec, M. ; Strunz, Pavel ; Gasser, U. ; Heczko, Milan ; Zálešák, J. ; Polák, Jaroslav
The nanostructure of Inconel 738LC Ni-superalloy strengthened by trimodal γ’ precipitates distribution was investigated after Low Cycle Fatigue (LCF) loading at temperature 700°C. Different microscopic techniques as Scanning Electron Microscope (SEM) equipped with STEM detector, transmission Kikuchi diffraction in the SEM, transmission electron microscope (TEM) in the bright field mode and high resolution transmission electron microscopes in STEM mode were used for the characterization of nanostructure. The characteristic morphology of γ’ precipitates was examined by ex-situ and in-situ Small Angle Neutron Scattering (SANS) at high temperatures. All microscopic techniques indicate that the morphology of γ’ precipitates distributed in the γ matrix as received state corresponds to two types, i.e. large cuboid-like precipitates with the size around 670 nm, and the spherical precipitates with the diameter 52 nm. After the LCF tests at temperature 700°C, the ex-situ SANS measurement yielded additional scattering intensities coming from another small γ’ precipitates with estimated size up to 10 nm.
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Impact of Heat Treatment Environment of Microstructure and Transformation Path in NiTi Shape Memory Alloy
Kuběnová, Monika ; Zálešák, Jakub ; Čermák, Jiří ; Barták, Tomáš ; Dlouhý, Antonín
We report results of differential scanning calorimetry (DSC) experiments in which heat flow (T) from and to Ti-50.9at%Ni shape memory samples was recorded during the temperature scan through a B2 B19’ transformation range. Prior to the DSC experiments, the samples were separately annealed in evacuated quartz capsules containing different hydrogen and helium mixtures with an overall filling pressure of 900 mbar. The quartz tubes containing the annealed samples were subsequently quenched into cold water. After quenching, the capsules were opened, martensitic transformations were investigated by DSC and the microstructure of the samples was assessed by transmission electron microscopy (TEM). Annealing in the mixtures with an increasing partial pressure of hydrogen led to a considerable drop in the latent heat associated with the B2 B19’ martensitic transformation. Results obtained using TEM suggest that hydrogen may function as a catalytic substance that accelerates the long range ordering of Ni atoms in early stages of Ni4Ti3-phase precipitation. The selected area diffraction study focused on patterns in <100>B2 and <110>B2 zones and provided evidence for diffuse scattering due to spatial modulations of the lattice constant. These variations in the background electron intensities might be related to a precursor of Ni4Ti3 phase in its early state of formation.
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Influence of Heat Treatment on Microstructure and Transformation Characteristics of NiTi Shape Memory Wires
Zálešák, Jakub ; Kuběnová, Monika ; Čermák, Jiří ; Svoboda, Milan ; Dlouhý, Antonín
The present study shows how heat treatments affect microstructure and transformation behaviour of superelastic Ni-rich NiTi shape memory wires. Wire samples were sealed into quartz tubes, filled with hydrogen reduction atmosphere, heated for 10 minutes at temperatures increasing in a range from 500 to 600°C and subsequently quenched into cold water. Characteristic transformation temperatures MS, MF, AS, AF, thermal hysteresis and latent heats were investigated using differential scanning calorimetry (DSC). We observed significant changes in DSC charts which recorded B2 → R and R → B19‘ phase martensitic transformations. Increasing temperature of the heat treatment resulted in a convergence of the two transformation peaks. R-transformation commenced at systematically lower temperatures and the beginning of the B19‘ transformation was shifted to higher temperatures with increasing temperature of the heat treatment. In parallel, latent heat of the overall B2 → B19‘ transformation clearly increases. We rationalize these significant changes in the transformation behaviour on the basis of the microstructural development during the heat treatment which is characterized by means of SEM, TEM and EBSD techniques.
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