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Vztah mezi stukturou a vlastnostmi litých niklových slitin
Smékalová, Jana ; Hutařová, Simona (oponent) ; Podrábský, Tomáš (vedoucí práce)
Niklové superslitiny jsou vyvinuty pro prostředí, která vyžadují korozivzdornost, žáruvzdornost a žárupevnost materiálu. Používají se hlavně pro součásti leteckých turbínových motorů a spalovacích turbín. Účinnost těchto zařízení se zvyšuje s rostoucí teplotou spalování, a proto je na jejich vývoj kladen velký důraz. Tato práce se zabývá vztahem mezi strukturou a vlastnostmi niklových superslitin Inconel 713LC a Inconel 738LC za pomoci světelné a elektronové mikroskopie.
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The numerical analysis of interactions between twins and precipitates in magnesium alloys
Bogdan, Miloš ; Gröger, Roman (oponent) ; Šiška, Filip (vedoucí práce)
The main objective of this thesis is to analyse the stress fields induced by twinning and their alteration due to the presence of precipitates at the twin tips. Analysed case describes {1012} 101 1 tensile twin with lamellar precipitates in magnesium alloy AZ31. The system is modelled using FE method as the 2D elastic elliptical inclusion with two rod like elastic precipitates in front of the ellipse embedded in plastic matrix modelled using crystal plasticity theory. Analysis of twins and precipitates with different thickness shows the inhibitory effect of precipitates on twin thickening. An intensity of this effect is changing with the twin thickness due to the complex interaction between twin, precipitate and induced plastic zone.
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The numerical analysis of interactions between twins and precipitates in magnesium alloys
Bogdan, Miloš ; Gröger, Roman (oponent) ; Šiška, Filip (vedoucí práce)
The main objective of this thesis is to analyse the stress fields induced by twinning and their alteration due to the presence of precipitates at the twin tips. Analysed case describes {1012} 101 1 tensile twin with lamellar precipitates in magnesium alloy AZ31. The system is modelled using FE method as the 2D elastic elliptical inclusion with two rod like elastic precipitates in front of the ellipse embedded in plastic matrix modelled using crystal plasticity theory. Analysis of twins and precipitates with different thickness shows the inhibitory effect of precipitates on twin thickening. An intensity of this effect is changing with the twin thickness due to the complex interaction between twin, precipitate and induced plastic zone.
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Vztah mezi stukturou a vlastnostmi litých niklových slitin
Smékalová, Jana ; Hutařová, Simona (oponent) ; Podrábský, Tomáš (vedoucí práce)
Niklové superslitiny jsou vyvinuty pro prostředí, která vyžadují korozivzdornost, žáruvzdornost a žárupevnost materiálu. Používají se hlavně pro součásti leteckých turbínových motorů a spalovacích turbín. Účinnost těchto zařízení se zvyšuje s rostoucí teplotou spalování, a proto je na jejich vývoj kladen velký důraz. Tato práce se zabývá vztahem mezi strukturou a vlastnostmi niklových superslitin Inconel 713LC a Inconel 738LC za pomoci světelné a elektronové mikroskopie.
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Analysis of cyclic plasticity of fatigued nickel based superalloys at elevated temperatures
Petrenec, Martin ; Tobiáš, Jiří ; Polák, Jaroslav ; Šmíd, Miroslav ; Chlupová, Alice ; Petráš, Roman
Cyclic strain controlled multiple step tests have been performed on cylindrical specimens of cast Inconel 738LC superalloy at 23 and 800 °C and Inconel 792-5A superalloy at 800 °C in laboratory atmosphere. The effect of temperature on the cyclic stress-strain response characterized by internal and effective cyclic stress components and on the dislocation arrangement has been studied. The evolution of the effective and internal stress components and effective elastic moduli were derived from the hysteresis loops analyzed according to the statistical theory of the hysteresis loop. Cyclic hardening/softening curves and shortened cyclic stress-strain curves were obtained at all temperatures in both superalloys. The shortened cyclic stress-strain curves (CSSCs) can be fitted by power law at all temperatures and for both materials. They are shifted to lower stresses with increasing temperature. The CSSC of Inconel 792-5A is shifted to higher stress amplitude in comparison with that of Inconel 738LC due to different number and type of precipitates. Observation of dislocation structures by TEM revealed cyclic strain localization into persistent slip bands. Cyclic stress-strain response is compared at all temperatures in both superalloys and discussed in relation to the changes of internal and effective stress components and microstructural parameters of the material. Higher stress response of the Inconel 792-5A than of the Inconel 738LC superalloy at 800°C is due to higher effective stresses of respective γ´ phases.
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