The purpose of this thesis is to characterize the intermetallic alloy Ti-Al by tests of propagation at high temperature (704° C) and compare the results obtained with those at room temperature. The propagation tests at room temperature were determined from previous work done in the laboratories of Politecnico di Milano. Then tests propagation at room temperature on the next generation intermetallic alloy Ti-Al (TNB alloy high-Nb), were carried out and the obtained results were compared with those on Ti-48Al-2Cr-2Nb. In addition a study of the mode of propagation of fatigue cracks in this type of materials was performed. Finally revisiting the results of a thesis work carried out previously on the same alloy and completing the fatigue tests, the models used to determine the relationship between fatigue limit and defect size (Kitagawa diagram) and their applicability to the Ti-Al alloys was verified
L’obbiettivo del lavoro di tesi è quello di caratterizzare la lega intermetallica Ti-Al mediante prove di propagazione ad alta temperatura (704°C) e confrontare i risultati ottenuti con quelli a temperatura ambiente. Le prove di propagazione a temperatura ambiente sono state determinate in lavori svolti precedentemente presso i laboratori del Politecnico di Milano. In seguito si eseguono prove di propagazione a temperatura ambiente sulla lega intermetallica Ti-Al di nuova generazione (lega TNB ad alto contenuto di Nb) e si confrontano i risultati ottenuti. Si esegue, inoltre, uno studio delle modalità di propagazione di cricche per fatica in questo tipo di materiali. Infine, rivisitando i risultati di un lavoro di tesi svolta precedentemente sulla stessa lega e completandone le prove sperimentali, si vuole verificare che i modelli utilizzati per determinare la relazione tra limite di fatica e dimensione del difetto (diagramma di Kitagawa), siano applicabili alle leghe TiAl
Integrità strutturale a temperatura ambiente e ad alta temperatura di leghe intermetalliche Ti-Al per applicazioni nelle turbine a gas
GALLINA, PASQUALE ALBERTO
2010/2011
Abstract
The purpose of this thesis is to characterize the intermetallic alloy Ti-Al by tests of propagation at high temperature (704° C) and compare the results obtained with those at room temperature. The propagation tests at room temperature were determined from previous work done in the laboratories of Politecnico di Milano. Then tests propagation at room temperature on the next generation intermetallic alloy Ti-Al (TNB alloy high-Nb), were carried out and the obtained results were compared with those on Ti-48Al-2Cr-2Nb. In addition a study of the mode of propagation of fatigue cracks in this type of materials was performed. Finally revisiting the results of a thesis work carried out previously on the same alloy and completing the fatigue tests, the models used to determine the relationship between fatigue limit and defect size (Kitagawa diagram) and their applicability to the Ti-Al alloys was verifiedFile | Dimensione | Formato | |
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2012_04_Gallina.pdf
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https://hdl.handle.net/10589/44823