|
|
Resonant ultrasound spectroscopy of ternary Cu-Al-Ni shape memory alloy compacts fabricated via SPS technology
Pavlík, Marek ; Spotz, Zdeněk (referee) ; Čížek, Jan (advisor)
This thesis deals with applicability of powder metalurgy for production of Cu-Al-Ni shape memory alloys. It is part of series of studies, inherently expanding experimental work with samples previously produced through optimized mechanical alloying and compaction via SPS method. In this work, the samples were thermally annealed and characterized by two advanced methods, DTA and RUS. Significant changes occur within the material at temperatures of 240 °C and 300 °C. The measurements indicated a presence of a martensitic transformation that could correspond to the desired SME phenomenon. Apparently, the changes were not triggered throughout the entire sample volume and further experimental progress is therefore expected in the near future.
|
|
|
Microstructure and mechanical properties of Ti15Mo alloy prepared by ECAP
Terynková, Anna ; Stráský, Josef (advisor) ; Šíma, Vladimír (referee)
In the bachelor thesis, mechanical properties and microstructure of Ti-15Mo alloy prepared by equal channel angular pressing were studied along with their dependence on the number of passes. Microhardness was studied by Vickers method, microstructure was studied by scanning electron microscopy and by electron back-scattered diffraction (EBSD). Finally, the elasticity modulus was measured by resonant ultra-sound spectroscopy. Mircohardness significantly increased after the first ECAP pass. After the second and the third pass it was almost constant and it again distinctly rose after the fourth pass. Grains with the size of hundreds of micrometres were observed in all samples. The volume fraction of twinned material increased with the number of passes. Deformation bands were also observed, namely in samples after two and three passes. Elastic modulus significantly increased with increasing deformation by ECAP and the evolution of elastic modulus is qualitatively similar to the evolution of microhardness. Considering that the material was processed by ECAP at 250řC, the omega phase may have formed during the processing. The increase of microhardness and elastic modulus can be explained by the increasing volume fraction of the omega phase.
|
|
|
Resonant ultrasound spectroscopy of ternary Cu-Al-Ni shape memory alloy compacts fabricated via SPS technology
Pavlík, Marek ; Spotz, Zdeněk (referee) ; Čížek, Jan (advisor)
This thesis deals with applicability of powder metalurgy for production of Cu-Al-Ni shape memory alloys. It is part of series of studies, inherently expanding experimental work with samples previously produced through optimized mechanical alloying and compaction via SPS method. In this work, the samples were thermally annealed and characterized by two advanced methods, DTA and RUS. Significant changes occur within the material at temperatures of 240 °C and 300 °C. The measurements indicated a presence of a martensitic transformation that could correspond to the desired SME phenomenon. Apparently, the changes were not triggered throughout the entire sample volume and further experimental progress is therefore expected in the near future.
|
guest ::
