Abstract
Atom-probe tomography (APT) and high-resolution transmission electron microscopy are used to study the chemical composition and nanostructural temporal evolution of Al3(Sc1-xZrx) precipitates in an Al-0.09 Sc-0.047 Zr at.% alloy aged at 300 °C. Concentration profiles, via APT, reveal that Sc and Zr partition to Al 3(Sc1-xZrx) precipitates and Zr segregates concomitantly to the α-Al/Al3(Sc1-xZrx) interface. The Zr concentration in the precipitates increases with increasing aging time, reaching a maximum value of 1.5 at.% at 576 h. The relative Gibbsian interfacial excess (ΓZrAl-Sc) of Zr, with respect to Al and Sc, reaches a maximum value of 1.24 ± 0.62 atoms nm-2 after 2412 h. The temporal evolution of Al3(Sc1-xZrx) precipitates is determined by measuring the time dependence of the depletion of the matrix supersaturation of Sc and Zr. The time dependency of the supersaturation of Zr does not follow the asymptotic t-1/3 law while that of Sc does, indicating that a quasi-stationary state is not achieved for both Sc and Zr.
Original language | English (US) |
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Pages (from-to) | 5401-5413 |
Number of pages | 13 |
Journal | Acta Materialia |
Volume | 53 |
Issue number | 20 |
DOIs | |
State | Published - Dec 2005 |
Funding
This research was supported by the United States Department of Energy, Basic Energy Sciences Division, under contract DE-FG02-98ER45721. We thank David C. Dunand, Peter W. Voorhees, Alexander Umantsev, Emmanuelle A. Marquis, Dieter Isheim, Jens Alkemper, and Jason T. Sebastian for discussions and Olof Hellman for continuous development of ADAM, now named APEX. Special thanks are due to Argonne National Laboratory and especially Dr. Roseann Csencsits for use of the JEOL 4000EXII. We also thank Ashurst Inc. for supplying the Al–Sc master alloy and Robert W. Hyland, Jr. and Alcoa Inc. for supplying the Al–Sc and Al–Zr master alloys and for useful discussions.
Keywords
- Al-Sc-Zr alloys
- High-resolution electron microscopy
- Microstructure
- Precipitation
- Three-dimensional atom-probe microscopy
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys