Paper Titles
Modelling the Phase Transformation from Al6(Mn,Fe) to α-Al(Mn,Fe)Si Phase during Homogenization of AA3xxx Alloys
p.297
Characterisation of AlFeSi Intermetallics in 6000 Series Aluminium Alloy Extrusions
p.303
Vacancy-Solute Aggregates in Al-Zn-Mg-(Cu, Ag)
p.309
Key Microstructural Features Responsible for Improved Stress Corrosion Cracking Resistance and Weldability in 7xxx Series Al Alloys Containing Micro / Trace Alloying Additions
p.315
Development of a New 7xxx Ageing Model
p.321
Grain Boundary Precipitate Modification for Improved Intergranular Corrosion Resistance
p.327
Microstructural Interactions during Stress Ageing a 7475 Aerospace Alloy
p.333
Influence of Zinc to Magnesium Ratio and Total Solute Content on the Strength and Toughness of 7xxx Series Alloys
p.339
Microstructural Evolution of a New Aerospace 7XXX Alloy during Retrogression and Re-Ageing Treatment
p.345

Development of a New 7xxx Ageing Model

Article Preview

Abstract:

A kinetic model has been developed to simulate the precipitate size distribution and the resulting yield strength during ageing of 7xxx alloys. The η phase is the only one considered. The kinetic model is mean field: precipitates of different sizes see each other through the average solid solution. Precipitates are assumed to be homogeneous in concentration and are allowed to change chemistry. Local equilibrium is assumed at the matrix-precipitate interface; the equilibrium concentrations are corrected by the curvature effect. Values of the equilibrium concentrations at the matrix-precipitate interface are solved by an iterative method: the resulting flux for each element must be compatible with equilibrium conditions and with the changing stoechiometry of the considered precipitate while maximizing the energy gained. The yield strength is derived from the precipitate size distribution through a mixture law combining the effect of each individual precipitate. The model can take into account non-isothermal treatments and can therefore simulate complicated multi-stage ageing treatment as well as a FSW weld. Results of the model are discussed and compared measurements.

You might also be interested in these eBooks
Aluminium Alloys 2006 - ICAA10 View Preview

Info:

Periodical:

Materials Science Forum (Volumes 519-521)

Pages:

321-326

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.519-521.321

Citation:

Cite this paper

Online since:

July 2006

Authors:

Christophe Sigli

Keywords:

AA7xxx, Aging Treatment (AT), Friction Stir Welding (FSW), Kinetic, Nucleation, Precipitation, Reversion

Export:

RIS, BibTeX

Price:

Permissions CCC:

Request Permissions

Permissions PLS:

Request Permissions

Сopyright:

© 2006 Trans Tech Publications Ltd. All Rights Reserved

Share:

Citation:

References

[1] R. Wagner and R. Kampmann, Homogeneous Second Phase Precipitation, in Phase Transformations in Materials, vol. 5, Materials Science and Technology, P. Haasen, Ed.: VCH, 1991, pp.213-303.

Google Scholar

[2] C. Sigli, Nucleation, Growth and Coarsening of Spherical Precipitates in Aluminum Alloys, presented at Aluminum Alloys: Their Physical and Mechanical Properties (ICAA7), Charlottesville, Virginia, USA, (2000).

DOI: 10.4028/www.scientific.net/msf.331-337.513

Google Scholar

[3] J. D. Robson and P. B. Prangnell, Dispersoid Precipitation and Process Moldelling in Zirconium Containing Commercial Aluminum Alloys, Acta Mater., vol. 49, pp.599-613, (2001).

DOI: 10.1016/s1359-6454(00)00351-7

Google Scholar

[4] M. Nicolas and A. Deschamps, Characterization and Modelling of Precipitate Evolution in an Al-Zn-Mg Alloy During Non Isothermal Heat Treatments, Acta Materialia, vol. 51, pp.6077-6094, (2003).

DOI: 10.1016/s1359-6454(03)00429-4

Google Scholar

[5] R. Kampmann and R. Wagner, Kinetics of Precipitation in Metastable Binary Alloys - Theory and Application to Cu - 1. 9at%Ti and Ni- 14at%Al, presented at Decomposition of Alloys: the Early Stages, Sonnenberg, Germany, (1983).

DOI: 10.1016/b978-0-08-031651-2.50018-5

Google Scholar

[6] A. Dillmann and G. E. A. Meier, A Refined Droplet Approach To The Problem of Homogeneous Neucleation From Vapor Phase, J. Chem. Phys., vol. 94, pp.3872-3884, (1991).

DOI: 10.1063/1.460663

Google Scholar

[7] A. Perini, G. Jacucci, and G. Martin, Interfacial Contribution to Cluster Free Energy, Surface Science, vol. 144, pp.56-66, (1984).

DOI: 10.1016/0039-6028(84)90703-9

Google Scholar

[8] C. Sigli and P. Guyot, Cluster Dynamics", presented at "Thermodynamics, Microstructure and Plasticity, NATO Advanced Study Institute, (2002).

Google Scholar

[9] J. W. Martin, Micromechanisms in particle-hardened alloys: Cambridge University Press, (1990).

Google Scholar

[10] C. Sigli, L. Maenner, C. Sztur, and R. Shahani, Phase Diagram, Solidification and Heat Treatment of Aluminum Alloys, presented at Aluminum Alloys: Their Physical and Mechanical Properties (ICAA6), Toyohashi, Japan, (1998).

Google Scholar

[11] H. Bakker, Diffusion in Solid Metals and Alloys, vol. 26. Berlin: Springer-Verlag, (1990).

Google Scholar