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Study of mechanical and thermal properties of nanoparticle-reinforced composites
Németh, Gergely ; Mathis, Kristián (advisor) ; Lukáč, Pavel (referee)
Title: Study of mechanical and thermal properties of composites reinforced by nanoparticles Author: Gergely Németh Department: Department of Physics of Materials Supervisor: RNDr. Kristián Máthis, Ph.D. Abstract: In the present work the deformation behavior of magnesium-based alloy AZ31 reinforced by SiC nanoparticles which was produced by horizontal continual casting is studied. Tension tests in the room temperature, compression tests in the temperature range of 20řC-300řC have been preformed. Samples was with two different orientation. Deformation strain rate was 10-3 s-1 . Simultaneously, the acoustic emission is recorded and studied. The mechanisms of plastic deformation of material are discussed mainly in term of mechanical twinning. Dependence of deformation behavior in compression on temperature is analyzed. The microstructure of original and deformed material is also studied. Keywords: magnesium alloys, composit material, mechanical twinning, metals with hexagonal structures.
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Study of deformation processes of perspective magnesium-based composites
Farkas, Gergely ; Mathis, Kristián (advisor) ; Száraz, Zoltán (referee)
The goal of the present work is investigation of deformation mechanisms in magnesium-based metal matrix composites and examination of the influence of morphology of strengthening phase on the mechanical properties. The microstructure of the specimen was studied by means of light optical and electron microscopy (SEM). Compression tests in the temperature range of 20řC-300řC were preformed. Acoustic emission measurements were performed during compression test at room temperature, whose help us elucidate the ongoing micromechanisms during the straining. Furthermore residual stress in the magnesium matrix at different strain levels was measured by neutron diffraction.
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Study of deformation processes in hexagonal materials
Čapek, Jan ; Mathis, Kristián (advisor) ; Karlík, Miroslav (referee)
The deformation mechanisms of commercially pure magnesium using advanced in-situ methods were investigated in the present work. Compression and tensile test were done at room temperature. Simultaneously, the neutron diffraction was measured and the acoustic emission was recorded. The microstructure of the deformed material was also studied by means of optical microscopy and electron back-scattered diffraction. These measurements provided information about twin nucleation and growth, microstructure changes and the influence of the orientation of grains on the number of twins and their shape. The values obtained were compared to the Elasto-Plastic Self-Consistent model, which provides information about the activity of deformation mechanisms. We focused on clarifying the influence of twinning activity on asymmetry between tensile and compression deformation.
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Phase transformations in Mg-Gd alloys
Stíbal, Adam ; Vlach, Martin (advisor) ; Mathis, Kristián (referee)
ývoj hořčíkový h slitin má ekonomi koEekologi ké opodst-tněníF yužití tě hto slitin je n- vzestupné tenden i - z-s-huje zejmén- do tr-nsportního pr·mysluD -le svoje upl-tnění n- hází i v medi íněF tedn- z metod zlepšení vl-stností hořčíku je legování jinými prvkyF vláš¡' do rý h výsledk· dos-huje legování prvky vzá ný h zeminF "ento typ slitinD kde legují ím prvkem je g-doliniumD jsou studovány v předklád-né prá i ve tře h tl-kově litý h slitiná h do kon entr- e IS hmF7F ředmětem prá e ylo studium fázový h tr-nsforE m- í při žíhání m-teriálu pomo í metody diferenční skenov- í k-lorimetrie při neizotermi kém žíháníF fyly pozorovány tři pro íh-jí í pro esy - spočteny jeE ji h -ktiv-ční energieF "ěmto pro es·m ylo n- zákl-dě srovnání s liter-turou přiř-zeno kl-strování -tom· qd - pre ipit- e met-st- ilní h fází β - β F I
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Study of twinning anisotropy of AZ31 magnesium alloy
Zdražilová, Zuzana ; Mathis, Kristián (advisor) ; Vlach, Martin (referee)
In the present work the deformation behaviour of magnesium-based alloy AZ31 which was produced by horizontal continual casting is investigated. Samples with two different orientations are deformed in tension and compression at strain rate of 10-3 s-1 in temperature range of 20 řC to 300 řC. Simultaneously, the acoustic emission is recorded and studied with focused on mechanical twinning. The mechanisms of plastic deformation of material and anisotropy between tension and compression are discussed. Dependence of deformation behaviour on temperature is analyzed. The microstructure of original and deformed material is also studied by means of optical microscopy.
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Study of mechanical properties of magnesium-based composites
Farkas, Gergely ; Mathis, Kristián (advisor) ; Drozd, Zdeněk (referee)
In the present work, the mechanical properties of AJ51 magnesium alloy and composite is studied. Compression tests in the temperature range of 20řC-300řC have been preformed. The microstructure of the specimen was studied by means of light optical microscopy. The work is focused on the elucidation of the micromechanisms acting during plastic deformation of the composite specimens. Further a comparison between the mechanical properties of alloy and the composite is presented.
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Dependence of mechanical properties of polycrystalline magnesium on microstructural parameters
Čapek, Jan ; Mathis, Kristián (advisor) ; Lukáč, Pavel (referee)
The deformation of commercially pure magnesium with various grain size in different temperatures is investigated in the present work. Compression and tensile test were done on three different samples in temperature range of 20řC-300řC. Samples are deformed at strain rate of 1,8 mm/min. Simultaneously, the acoustic emission is recorded. The microstructure of the deformed material is also studied by means of optical microscopy. We focus on twinning activity at various temperatures and asymmetry between tensile and compression deformation.
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Microstructural evolution of equal-channel angular pressed IF steel
Krajňák, Tomáš ; Mathis, Kristián (advisor) ; Drozd, Zdeněk (referee)
Equal channel angular pressing (ECAP) belongs to advanced technologies for improving mechanical properties of materials. In the present work the influence of number of pressing by route BC on grain size, density and type of dislocation, evolution of microstructure and mechanical properties of IF steel has been investigated by means of optical microscopy, electron back-scattering diffraction (EBSD), diffraction profile analysis, microhardness testing and tensile deformations. It has been found, that the grain size decreasing with increasing number of passes. Simultaneously, the microhardness, density of dislocation and maximum true strength has been increased. The evolution of microstructure with increasing pressing number, particularly the forming of high-angle boundaries has been also examined.
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