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Reaction synthesis of bulk Fe-Al intermetallic materials
Dyčková, Lucie ; Hutařová, Simona (referee) ; Jan, Vít (advisor)
Bachelor’s thesis deals with iron aluminides. In literature analysis are the best known and the most widely used intermetallics materials, diffusion and other possible processing technologies of intermetallic materials. In experimental part was used sprayed coating. This sprayed coating was produced by cold gas-dynamic spray. In this thesis were analysed changes in microstructure of iron aluminides depending on annealing temperature. This thesis contains photographs of microstructure and analyses from electron microscopy and measurement of microhardness.
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Reaction synthesis of bulk intermetallic materials from kinetic spraying deposits
Stejskal, Pavel ; Roupcová, Pavla (referee) ; Jan, Vít (advisor)
This work deals with issues of preparation of intermetallics based on iron, nickel and titanium aluminides. It works with an idea of preparation of bulk material by reaction synthe-sis from kinetic spraying deposits by cold spray. Theoretical part is concerned with phases and compounds of these aluminides for structural applications, their characteristics and present fabrication. In experimental part there are studied microstructures created by annealing of deposits.
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Crack Resistance Characterization in TiAl Intermetallics with Enhanced Toughness
Dlouhý, Ivo ; Stratil, Luděk ; Fukutomi, H. ; Hasegawa, M.
The paper is focused on the analysis of the role of lamellar microstructure in fracture performance of model TiAl intermetallic compound. Coarse lamellar colonies and, at the same time, fine lamellar morphology were prepared by compressive deformation at 1553 K (region of stable alpha phase in TiAl equilibrium diagram) followed by controlled cooling to 1473 K (region of alpha+gamma phase) with delay on this temperature and then cooling down. The fracture toughness was evaluated by means of chevron notch technique. In addition, because of enhanced toughness, crack resistance curves were obtained by load - unload technique of pre-racked beams, namely in two directions of crack propagation relative to lamellar structure. Extensive development of shear ligament toughening mechanism was observed in fracture surfaces leading to quite good fracture toughness thanks to the heat treatment applied.
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Reaction synthesis of bulk intermetallic materials from kinetic spraying deposits
Stejskal, Pavel ; Roupcová, Pavla (referee) ; Jan, Vít (advisor)
This work deals with issues of preparation of intermetallics based on iron, nickel and titanium aluminides. It works with an idea of preparation of bulk material by reaction synthe-sis from kinetic spraying deposits by cold spray. Theoretical part is concerned with phases and compounds of these aluminides for structural applications, their characteristics and present fabrication. In experimental part there are studied microstructures created by annealing of deposits.
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Reaction synthesis of bulk Fe-Al intermetallic materials
Dyčková, Lucie ; Hutařová, Simona (referee) ; Jan, Vít (advisor)
Bachelor’s thesis deals with iron aluminides. In literature analysis are the best known and the most widely used intermetallics materials, diffusion and other possible processing technologies of intermetallic materials. In experimental part was used sprayed coating. This sprayed coating was produced by cold gas-dynamic spray. In this thesis were analysed changes in microstructure of iron aluminides depending on annealing temperature. This thesis contains photographs of microstructure and analyses from electron microscopy and measurement of microhardness.
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Interakce mezi Ti-Al-Nb taveninou a Y2O3 kelímky
Barták, Tomáš ; Dlouhý, Antonín ; Dočekalová, Kateřina ; Zemčík, L.
The present paper focuses on interactions between intermetallic melts (Ti-46Al-7Nb-0.7Cr-0.1Si-0.2Ni alloy (at%)) and ceramic crucibles based on the Y2O3 refractory. Different levels of superheat and exposure time are taken into account. Vacuum induction melting (VIM) experiments were performed using the vacuum furnace BALZERS VSG 02. The controlled argon atmosphere inside the furnace volume was kept at the pressure level of 0.133 bar during the melting experiments. The reactions at the melt - crucible interface were studied by means of scanning electron microscopy (SEM) equipped with the energy dispersive x-ray analyzer (EDX). There has been clear benefit when a common refractory like alumina has been replaced by yttria. However, the results obtained in this study show, that the long - term exposure at melting temperatures above 1650°C lead to notable reactions at the interface. We discuss the stability of the melt - ceramic system using principles of thermodynamic equilibrium.
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