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Preparation and analysis of experimental refractory alloy
Krupica, Roman ; Štěpánek, Roman (referee) ; Jan, Vít (advisor)
This thesis is focused on a preparation and especially on an analysis of an experimental Fe, Cr, W, Ni, Al, Ti refractory alloy. The first, theoretical, part of the work deals with refractory materials problematics in general. The second part of the work, experimental, is focused on the process of material preparation and its partial analyses in terms of hardness, but mainly in terms of structure. Light microscopy and scanning electron microscopy were used for these analyses, and energy dispersive spectrometry was used to analyze the chemical composition. The achieved results in all material states indicate that titanium nitrides randomly occur in the structure due to the nitrogen contamination. In the cast state, the material appears to be almost completely homogeneous without any significant casting defects. At grain boundaries, there is a uniform structured Laves phase population based on tungsten. After annealing at 800 °C/1h small fine and evenly distributed precipitates of the Laves phase occur together with even smaller precipitates of an intermetallic phase probably based on nickel and aluminum. Also, the amount of tungsten in the Laves phase at the grain boundaries was increased. During annealing at 1000 °C/5h, the precipitation particles of the Laves phase significantly coarsened and the occurrence of the intermetallic precipitates became uneven. At the same time, the Laves phase at the grain boundaries was again found to have more tungsten in it.
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Preparation and analysis of experimental refractory alloy
Krupica, Roman ; Štěpánek, Roman (referee) ; Jan, Vít (advisor)
This thesis is focused on a preparation and especially on an analysis of an experimental Fe, Cr, W, Ni, Al, Ti refractory alloy. The first, theoretical, part of the work deals with refractory materials problematics in general. The second part of the work, experimental, is focused on the process of material preparation and its partial analyses in terms of hardness, but mainly in terms of structure. Light microscopy and scanning electron microscopy were used for these analyses, and energy dispersive spectrometry was used to analyze the chemical composition. The achieved results in all material states indicate that titanium nitrides randomly occur in the structure due to the nitrogen contamination. In the cast state, the material appears to be almost completely homogeneous without any significant casting defects. At grain boundaries, there is a uniform structured Laves phase population based on tungsten. After annealing at 800 °C/1h small fine and evenly distributed precipitates of the Laves phase occur together with even smaller precipitates of an intermetallic phase probably based on nickel and aluminum. Also, the amount of tungsten in the Laves phase at the grain boundaries was increased. During annealing at 1000 °C/5h, the precipitation particles of the Laves phase significantly coarsened and the occurrence of the intermetallic precipitates became uneven. At the same time, the Laves phase at the grain boundaries was again found to have more tungsten in it.
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