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Effect cyclic heat treatment on structure of TiAl alloy
Vraspírová, Eva ; Němec, Karel (referee) ; Petrenec, Martin (advisor)
The subject of this master thesis is focused to the refining of the cast structure of gamma-TiAl–2Nb alloy using cyclic heat treatment and to the analysis of the grain refining mechanism. Structure evolution after applied cycles of heat treatment was characterized using light, laser and electron microscopy and using microhardness tests. Application of five heat treatment cycles during which two phase transformations (eutectoid and alpha-recrystallization reactions) repeatedly took place resulted in refining of the cast columnar structure having the mean grain size 512 microns to fully lamellar structure containing gamma and alpha2 phases having the mean grain size 229 microns. Lamellae thickness of gamma was not changed while the thickness of alpha2 phase decreased, up to 78 nm. Refining of alpha2 phase resulted in the increase of the microhardness by 20 %. The recrystallized cast structure obtained by cyclic heat treatment and the knowledge on the mechanisms of the refining the structure were compared with the literature data and were discussed in order to propose more efficient procedure for refining thermal treatment of cast TiAl alloys.
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Application of Surface Treatment on Hand Tools
Vraspírová, Eva ; Klakurková, Lenka (referee) ; Doležal, Pavel (advisor)
Bachelor's thesis deals with problems of materials, which are used to production of hand tools and implements. The theoretical part is focused on tool steels, their mechanical and technological characteristics and to their heat processing. Below there are well-arranged and described surface modification, which are applied to materials nowadays. The next part is focused on modern technology of surface modification, which are applied to hand tools. The research is mainly focused on technology of production of bits by company Wera Werk Ltd, which is deal with production and distribution of hand tightening tools, such as screwdrivers, angular keys, plug keys, bits and torque tools. Attention is also paid to technology of surface modification, e.g. based on zinc phosphate, nickel, nickel-gold and nickel-diamond-gold, used for these tools and to problems of painting. To elements interaction study light microscopy, the hardness measurement by Vickers and Brinell and scanning electron microscopy equipped by energy dispersive microanalyses.
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Effect cyclic heat treatment on structure of TiAl alloy
Vraspírová, Eva ; Němec, Karel (referee) ; Petrenec, Martin (advisor)
The subject of this master thesis is focused to the refining of the cast structure of gamma-TiAl–2Nb alloy using cyclic heat treatment and to the analysis of the grain refining mechanism. Structure evolution after applied cycles of heat treatment was characterized using light, laser and electron microscopy and using microhardness tests. Application of five heat treatment cycles during which two phase transformations (eutectoid and alpha-recrystallization reactions) repeatedly took place resulted in refining of the cast columnar structure having the mean grain size 512 microns to fully lamellar structure containing gamma and alpha2 phases having the mean grain size 229 microns. Lamellae thickness of gamma was not changed while the thickness of alpha2 phase decreased, up to 78 nm. Refining of alpha2 phase resulted in the increase of the microhardness by 20 %. The recrystallized cast structure obtained by cyclic heat treatment and the knowledge on the mechanisms of the refining the structure were compared with the literature data and were discussed in order to propose more efficient procedure for refining thermal treatment of cast TiAl alloys.
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|
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Application of Surface Treatment on Hand Tools
Vraspírová, Eva ; Klakurková, Lenka (referee) ; Doležal, Pavel (advisor)
Bachelor's thesis deals with problems of materials, which are used to production of hand tools and implements. The theoretical part is focused on tool steels, their mechanical and technological characteristics and to their heat processing. Below there are well-arranged and described surface modification, which are applied to materials nowadays. The next part is focused on modern technology of surface modification, which are applied to hand tools. The research is mainly focused on technology of production of bits by company Wera Werk Ltd, which is deal with production and distribution of hand tightening tools, such as screwdrivers, angular keys, plug keys, bits and torque tools. Attention is also paid to technology of surface modification, e.g. based on zinc phosphate, nickel, nickel-gold and nickel-diamond-gold, used for these tools and to problems of painting. To elements interaction study light microscopy, the hardness measurement by Vickers and Brinell and scanning electron microscopy equipped by energy dispersive microanalyses.
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