In this thesis work are analysed the effects of the combined presence of bismuth, a common impurity in secondary aluminium alloys, and gadolinium, a lanthanide added as modifying agent of the eutectic structure in Al-Si-Mg and Al-Si-Cu-Mg alloys. Thermal analysis has shown that the presence of 200ppm of Bismuth with gadolinium does not significantly alter the solidification kinetics of the alloys considered. The observation of the morphology and dimensions of the eutectic carried out with the optical microscope has allowed to notice that there has not been a significant variation in the action of gadolinium following its addition combined with the bismuth. Scanning electron microscope analysis showed the tendency of bismuth particles to nucleate near gadolinium-rich intermetallics, leading to consider the possibility that they could act as a preferential nucleation sites.
Nel lavoro di tesi proposto si sono analizzati gli effetti della presenza combinata di bismuto, elemento comunemente presente come impurezza nelle leghe di alluminio secondarie, e Gadolinio aggiunto volontariamente come affinante e modificante della struttura eutettica, in leghe Al-Si-Mg e Al-Si-Cu-Mg. L’analisi termica ha dimostrato come la presenza di 200ppm di Bismuto con il gadolinio non alteri significativamente la cinetica di solidificazione delle leghe considerate. L’osservazione della morfologia e delle dimensioni dell’eutettico svolta al microscopio ottico ha permesso di notare come non vi sia stata una significativa variazione nell’azione del gadolinio in seguito alla sua addizione combinata con il bismuto. L’analisi al microscopio elettronico a scansione ha permesso di notare la tendenza delle particelle di bismuto di nucleare in prossimità degli intermetallici ricchi di gadolinio, portando a considerare la possibilità che quest’ultimi possano agire da sito di nucleazione preferenziale
Effetti dell'interazione tra Bismuto e Gadolinio sulla cinetica di solidificazione e sulla microstruttura in leghe Al-Si-Mg e Al-Si-Cu-Mg da fonderia
NARDELLO, ELIA
2022/2023
Abstract
In this thesis work are analysed the effects of the combined presence of bismuth, a common impurity in secondary aluminium alloys, and gadolinium, a lanthanide added as modifying agent of the eutectic structure in Al-Si-Mg and Al-Si-Cu-Mg alloys. Thermal analysis has shown that the presence of 200ppm of Bismuth with gadolinium does not significantly alter the solidification kinetics of the alloys considered. The observation of the morphology and dimensions of the eutectic carried out with the optical microscope has allowed to notice that there has not been a significant variation in the action of gadolinium following its addition combined with the bismuth. Scanning electron microscope analysis showed the tendency of bismuth particles to nucleate near gadolinium-rich intermetallics, leading to consider the possibility that they could act as a preferential nucleation sites.File | Dimensione | Formato | |
---|---|---|---|
Nardello_Elia.pdf
accesso riservato
Dimensione
5.2 MB
Formato
Adobe PDF
|
5.2 MB | Adobe PDF |
The text of this website © Università degli studi di Padova. Full Text are published under a non-exclusive license. Metadata are under a CC0 License
https://hdl.handle.net/20.500.12608/43206