Název: Fyzikální vlastnosti ultrajemnozrrných polykrystalů slitin na bázi hořčíku
Překlad názvu: Physical properties of ultrafine-grained polycrystals of magnesium based alloys
Autoři: Vrátná, Jitka ; Janeček, Miloš (vedoucí práce) ; Kužel, Radomír (oponent)
Typ dokumentu: Diplomové práce
Rok: 2010
Jazyk: eng
Abstrakt: The objective of the thesis is the study of microstructure evolution, mechanical properties, defect structure and corrosion resistance of ultra-ne grained magnesium alloy AZ31 prepared by a combined two-step process: the extrusion and the equal-channel angular pressing (ECAP). The microstructure development was studied using light and transmission electron microscopy and electron backscatter diffraction (EBSD). Mechanical properties were studied by microhardness measurement and tensile tests and the defect structure by positron annihilation spectroscopy (PAS). The results of tensile tests indicates that the characteristic stress 0.2 increases slightly with increasing number of ECAP passes only to the second pass and then decreases signicantly with additional ECAP straining. This behaviour is in accordance with the results of PAS. EBSD measurements show that the microstructure of extruded and ECAPed material has a bimodal distribution of grain sizes. The bimodal distribution becomes homogeneous with increasing number of ECAP passes and no remaining large grains are observed after 8 passes. The average grain size in the specimen after 8 passes is in the submicrometer range and the fraction of high-angle grain boundary (HAGB) is approximately 80%. The extruded specimens after 8 ECAP passes show the best...

Instituce: Fakulty UK (VŠKP) (web)
Informace o dostupnosti dokumentu: Dostupné v digitálním repozitáři UK.
Původní záznam: http://hdl.handle.net/20.500.11956/27346

Trvalý odkaz NUŠL: http://www.nusl.cz/ntk/nusl-282539


Záznam je zařazen do těchto sbírek:
Školství > Veřejné vysoké školy > Univerzita Karlova > Fakulty UK (VŠKP)
Vysokoškolské kvalifikační práce > Diplomové práce