Coarsening kinetics of nanoscale Al3Sc precipitates in an Al-Mg-Sc alloy.
- Northwestern University, Evanston, IL
The effects of Mg alloying on the temporal evolution of Al{sub 3}Sc (L1{sub 2} structure) nanoscale precipitates are investigated, focusing on the morphology and coarsening kinetics of Al{sub 3}Sc precipitates in an Al-2.2 Mg-0.12 Sc at.% alloy aged between 300 and 400 C. Approximately spheroidal precipitates are obtained after aging at 300 C and irregular morphologies are observed at 400 C. The coarsening behavior is studied using conventional and high-resolution transmission electron microscopies to obtain the temporal evolution of the precipitate radius, and atom-probe tomography is employed to measure the Sc concentration in the {alpha}-matrix. The coarsening kinetics are analyzed using a coarsening model developed by Kuehmann and Voorhees for ternary systems [Kuehmann CJ, Voorhees PW. Metall Mater Trans A 1996;27:937]. Values of the interfacial free energy and diffusion coefficient for Sc diffusion in this Al-Mg-Sc alloy at 300 C are independently calculated, and are in good agreement with the calculated value of interfacial free energy and the experimental diffusivity obtained for the Al-Sc system.
- Research Organization:
- Sandia National Laboratories
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 972470
- Report Number(s):
- SAND2005-4547J
- Journal Information:
- Proposed for publication in Acta Materialla., Journal Name: Proposed for publication in Acta Materialla.
- Country of Publication:
- United States
- Language:
- English
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