Small angle x-ray scattering (SAXS) with synchrotron radiation was used to characterize nano-sized voids in different nominally pure aluminum (Al) alloys produced by quenching. The scattering signal from nano-voids is shown to be predictable from SAXS theory, and the information related to the void population confirm past experiments and reveal new details about quench-void formation in Al. Specifically, voids were produced in 99.97 at.% to 99.9994 at.% Al alloys by infrared heating to 450 – 625 °C followed by controlled rapid quenching at 10^3 to 10^5 °C/s. For changing processing conditions, the size of voids varied between 5 to 11 nm, and the density of voids varied by over an order of magnitude. Results from SAXS were consistent with TEM observations performed on the same specimens, indicating that synchrotron SAXS can be reliably used to characterize nano-voids produced in quenched Al. Factors determined to affect voids were consistent with previous studies, except that the present nano-voids dissolved after only 3 min. at 145 °C, indicating that quenched nano-voids are less stable than previously determined. SAXS also showed that void size is sensitive to quench temperature and quench rate. The activation energies for void nucleation and growth were determined to be 0.75 ± 0.10 and 0.19 ± 0.03 eV/at., respectively, confirming that hydrogen and di-vacancies take part in nucleation and growth during quenching. It was concluded that the non-linear tail of the quench curve plays a crucial role in void formation, and that voids form when long range diffusion is inhibited. This information can be utilized to design new Al alloys that limit incipient void formation, which is detrimental to properties such as formability. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2008-04-25 15:17:30.211 / Natural Sciences and Engineering Research Council of Canada;
General Motors of Canada Limited
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OKQ.1974/1177 |
| Date | 28 April 2008 |
| Creators | Westfall, Luke Aidan |
| Contributors | Queen's University (Kingston, Ont.). Theses (Queen's University (Kingston, Ont.)) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | 5761113 bytes, application/pdf |
| Rights | This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner. |
| Relation | Canadian theses |
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