Experiment and modeling of ultrafast precipitation in an ultrafine-grained Al–Cu–Sc alloy

Experimental results revealed that the aging precipitation behaviors were significantly enhanced in an ultrafine grained (UFG) Al–Cu–Sc alloy when compared with its coarse grained (CG) counterpart. In the UFG Al–Cu–Sc alloy aged at 398K for 20h, a large number of θ′-Al2Cu particles with an average r...

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Bibliographic Details
Published in:	Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2014-06, Vol.607, p.596-604
Main Authors:	Jiang, L., Li, J.K., Cheng, P.M., Liu, G., Wang, R.H., Chen, B.A., Zhang, J.Y., Sun, J., Yang, M.X., Yang, G.
Format:	Article
Language:	eng
Subjects:	Alloy development ALUMINUM ALLOYS (50 TO 99 AL) Aluminum base alloys Al–Cu–Sc alloy Condensed matter: structure, mechanical and thermal properties COPPER ALUMINUM ALLOYS Cross-disciplinary physics: materials science rheology DIFFUSION Diffusion in solids Enhanced diffusion Equations of state, phase equilibria, and phase transitions Exact sciences and technology General studies of phase transitions GRAIN SIZE AND SHAPE Materials science MATHEMATICAL ANALYSIS Mathematical models Microstructure MICROSTRUCTURES Modeling NUCLEATION Phase diagrams and microstructures developed by solidification and solid-solid phase transformations Physics Precipitation Precipitation behavior Solid solution, precipitation, and dispersion hardening aging SPD Structural materials Transport properties of condensed matter (nonelectronic) Treatment of materials and its effects on microstructure and properties Ultrafine grain
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Summary:	Experimental results revealed that the aging precipitation behaviors were significantly enhanced in an ultrafine grained (UFG) Al–Cu–Sc alloy when compared with its coarse grained (CG) counterpart. In the UFG Al–Cu–Sc alloy aged at 398K for 20h, a large number of θ′-Al2Cu particles with an average radius of about 38nm were precipitated within the grain interior. While in the CG alloy aged at the same condition, no precipitations were found. The ultrafast precipitation behaviors observed in the UFG alloy is rationalized by developing a precipitation kinetics model. This model is based on the classical N-model framework of Kampmann and Wagner (KWN), but is modified to capture some precipitation features in the UFG regime, such as highly enhanced diffusion and greatly reduced nucleation energy barriers. The modified model yields predictions in good agreement with experimental data, which are several orders of magnitude faster than those predicted by the classical model. This work indicates that the classical N-model, after some modifications, is still applicable for the quantitative description of precipitation behaviors in UFG Al alloys.
ISSN:	0921-5093 1873-4936