Pipe-diffusion ripening of Si precipitates in Al-0.5%Cu-1%Si thin films |
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Authors: | M. Legros B. Kaouache P. Gergaud O. Thomas G. Dehm T.J. Balk |
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Affiliation: | 1. CEMES-CNRS , 29 rue Jeanne Marvig, 31055 Toulouse, France;2. LPMM , ENSAM, Technopole , 4 rue Augustin Fresnel, 57078 Metz, France;3. Laboratoire TECSEN , Faculté des Sciences de St Jér?me , 13397 Marseille, France;4. Max-Planck-Institute for Metals Research and Institut für Metallkunde , University of Stuttgart Heisenbergstr. 3 , 70569 Stuttgart, Germany;5. Department of Chemical and Material Eng. , University of Kentucky , Lexington, KY 40506, USA |
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Abstract: | Al-0.5%Cu-1%Si thin films deposited onto oxidized Si substrates were subjected to both wafer curvature and in situ transmission electron microscopy thermal cycling experiments between room temperature and 450°C. The evolution of precipitates was monitored during cycling. Chemical analysis revealed that the precipitates are pure Si. Their average size increased from 80?nm in the as-deposited state to 300?nm after thermal cycling. The Si precipitates serve as anchoring points for dislocations and grain boundaries. Direct evidence for pipe-diffusion ripening was found in the vicinity of a dissolving precipitate. Real-time measurement of the radius of the precipitate allowed us to estimate the coefficient of pipe diffusion of Si in Al at this temperature. As expected, this coefficient is several orders of magnitude larger than the volume diffusion coefficient. The impact of precipitate ripening on the mechanical behavior of these alloyed Al films will also be discussed. |
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