Additive friction stir deposition (AFSD) is a solid-state additive manufacturing (AM) technique that breaks down large constituent particles into more refined and uniformly disturbed microstructure. AFSD was used to print Al-Ce alloys. Current commercial Al-alloys upon elevated temperatures go through dissolution and coarsening of strengthening precipitates causing mechanical degradation of these alloys. Al-Ce alloys do not have this issue as cerium's low solubility restricts dissolution into the aluminum matrix at elevated temperatures, thus giving great thermal stability to the microstructure. Al-Ce alloys lack solid solubility that affects the solid solution strengthening and precipitation strengthening. Al-Ce alloys have limitation at room temperature as they can only reach a maximum of ~65 MPa yield strength. Elements like magnesium have been added to alloy to enable solid solution strengthening, and scandium to enable precipitation strengthening to improve strength before going through the AFSD process. By adding new elements to the Al-Ce alloys, an increase in the yield strength from ~60 MPa to ~200 MPa was achieved before AFSD. The casted alloys form coarse particles that reach 300 µm in size; resulting in stress concentration that causes material fracture before necking, giving >10% ductility. AFSD breaks down these coarse particles to increase strength and ductility increases. The particles were broken down to >20 µm which increased the ductility to 10%. The results of this research shows that Al-Ce alloys are able to reach commercial aluminum alloy mechanical standards of 400 MPa ultimate tensile strength and 10% ductility at room temperature for aerospace applications.
| Identifer | oai:union.ndltd.org:unt.edu/info:ark/67531/metadc2257751 |
| Date | 12 1900 |
| Creators | Davis, Devin Fredric |
| Contributors | Mishra, Rajiv S., Vasudevan, Vijay, Haridas, Ravi S., Weiss, David |
| Publisher | University of North Texas |
| Source Sets | University of North Texas |
| Language | English |
| Detected Language | English |
| Type | Thesis or Dissertation |
| Format | Text |
| Rights | Public, Davis, Devin Fredric, Copyright, Copyright is held by the author, unless otherwise noted. All rights Reserved. |
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