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Thermomechanical fatigue of nickel-based superalloys
Pech, Filip ; Škorík, Viktor (referee) ; Šulák, Ivo (advisor)
The main objective of present bachelor thesis is to compile literature review of thermomechanical fatigue of nickel-based superalloys. Superalloys were developed to work at high temperatures, where sufficiently high strength, oxidation resistance, creep resistance, and resistance to other high temperature adverse effects have to be ensured. Superalloys are despite efforts to find alternatives still widely used and therefore it is necessary to know their properties and limitations. The present review compiles basic overview of nickel-based superalloys based on specialized publications. First of all, classification of Ni-based superalloys, chemical composition, along with an overview of the most important phases, which are affecting properties of superalloys were studied in detail. The second chapter describes basics of isothermal fatigue of materials, its definition, description of mechanism and basic fatigue life curves. Penultimate chapter of this literature review deals with thermomechanical fatigue and the structure of text is similar to chapter about isothermal fatigue. In the last chapter is given an overview of thermomechanical fatigue of different types of nickel-based superalloys.
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New compositions of advanced oxide dispersion steels based on rare earth elements
Pech, Filip ; Kuběna, Ivo (referee) ; Hadraba, Hynek (advisor)
The main objective of present diploma thesis is to prepare three different classes of steels, differing by their content of chromium: 9Cr, 14Cr, 17Cr steels and their oxide dispersion strengthened variants. Steels were prepared from atomic and pre-alloyed powders by the mechanical alloying and compacted by the spark plasma sintering method. Used strengthening elements were yttrium, which is most commonly used, and aluminium. Preparation of oxide dispersion was done in two ways: direct adding of yttria and alumina and inner oxidation of aluminium and yttrium. In the experimental part has been found, that it is possible to make oxide dispersion by both ways, but aluminium strengthened steel has to be prepared by inner oxidation to ensure fine oxide dispersion.
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New compositions of advanced oxide dispersion steels based on rare earth elements
Pech, Filip ; Kuběna, Ivo (referee) ; Hadraba, Hynek (advisor)
The main objective of present diploma thesis is to prepare three different classes of steels, differing by their content of chromium: 9Cr, 14Cr, 17Cr steels and their oxide dispersion strengthened variants. Steels were prepared from atomic and pre-alloyed powders by the mechanical alloying and compacted by the spark plasma sintering method. Used strengthening elements were yttrium, which is most commonly used, and aluminium. Preparation of oxide dispersion was done in two ways: direct adding of yttria and alumina and inner oxidation of aluminium and yttrium. In the experimental part has been found, that it is possible to make oxide dispersion by both ways, but aluminium strengthened steel has to be prepared by inner oxidation to ensure fine oxide dispersion.
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Thermomechanical fatigue of nickel-based superalloys
Pech, Filip ; Škorík, Viktor (referee) ; Šulák, Ivo (advisor)
The main objective of present bachelor thesis is to compile literature review of thermomechanical fatigue of nickel-based superalloys. Superalloys were developed to work at high temperatures, where sufficiently high strength, oxidation resistance, creep resistance, and resistance to other high temperature adverse effects have to be ensured. Superalloys are despite efforts to find alternatives still widely used and therefore it is necessary to know their properties and limitations. The present review compiles basic overview of nickel-based superalloys based on specialized publications. First of all, classification of Ni-based superalloys, chemical composition, along with an overview of the most important phases, which are affecting properties of superalloys were studied in detail. The second chapter describes basics of isothermal fatigue of materials, its definition, description of mechanism and basic fatigue life curves. Penultimate chapter of this literature review deals with thermomechanical fatigue and the structure of text is similar to chapter about isothermal fatigue. In the last chapter is given an overview of thermomechanical fatigue of different types of nickel-based superalloys.
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