Characterization of novel microstructures in Al-Fe-V-Si and Al-Fe-V-Si-Y alloys processed at intermediate cooling rates
dc.contributor.advisor | Kaufman, Michael J. | |
dc.contributor.author | Marshall, Ryan | |
dc.date.accessioned | 2016-01-19T16:44:30Z | |
dc.date.accessioned | 2022-02-03T12:53:58Z | |
dc.date.available | 2016-01-19T16:44:30Z | |
dc.date.available | 2022-02-03T12:53:58Z | |
dc.date.issued | 2015 | |
dc.identifier | T 7945 | |
dc.identifier.uri | https://hdl.handle.net/11124/170004 | |
dc.description | 2015 Fall. | |
dc.description | Includes illustrations (some color). | |
dc.description | Includes bibliographical references. | |
dc.description.abstract | Samples of an Al-Fe-V-Si alloy with and without small Y additions were prepared by copper wedge-mold casting. Analysis of the microstructures developed at intermediate cooling rates revealed the formation of an atypical morphology of the cubic α-Al12(Fe/V)3Si phase (Im3¯ space group with a = 1.26 nm) in the form of a microeutectic with α-Al that forms in relatively thick sections. This structure was determined to exhibit promising hardness and thermal stability when compared to the commercial rapidly solidified and processed Al-Fe-V-Si (RS8009) alloy. In addition, convergent beam electron diffraction (CBED) and selected area electron diffraction (SAD) were used to characterize a competing intermetallic phase, namely, a hexagonal phase identified as h-AlFeSi (P6/mmm space group with a = 2.45 nm c = 1.25 nm) with evidence of a structural relationship to the icosahedral quasicrystalline (QC) phase (it is a QC approximant) and a further relationship to the more desirable α-Al12(Fe/V)3Si phase, which is also a QC approximant. The analysis confirmed the findings of earlier studies in this system, which suggested the same structural relationships using different methods. As will be shown, both phases form across a range of cooling rates and appear to have good thermal stabilities. Additions of Y to the alloy were also studied and found to cause the formation of primary YV2Al20 particles on the order of 1 μm in diameter distributed throughout the microstructure, which otherwise appeared essentially identical to that of the Y-free 8009 alloy. The implications of these results on the possible development of these structures will be discussed in some detail. | |
dc.format.medium | born digital | |
dc.format.medium | masters theses | |
dc.language | English | |
dc.language.iso | eng | |
dc.publisher | Colorado School of Mines. Arthur Lakes Library | |
dc.relation.ispartof | 2015 - Mines Theses & Dissertations | |
dc.rights | Copyright of the original work is retained by the author. | |
dc.subject | aluminum | |
dc.subject | approximant | |
dc.subject | chill cast | |
dc.subject | high temperature | |
dc.subject | quasicrystal | |
dc.subject | RS8009 | |
dc.title | Characterization of novel microstructures in Al-Fe-V-Si and Al-Fe-V-Si-Y alloys processed at intermediate cooling rates | |
dc.type | Text | |
dc.contributor.committeemember | Midson, Stephen | |
dc.contributor.committeemember | Field, Robert | |
thesis.degree.name | Master of Science (M.S.) | |
thesis.degree.level | Masters | |
thesis.degree.discipline | Metallurgical and Materials Engineering | |
thesis.degree.grantor | Colorado School of Mines |