Quantitative evaluation of precipitates in an Al-Zn-Mg-Cu alloy after isothermal aging

Journal Article · Wed Mar 15 04:00:00 EST 2006 · Materials Characterization

DOI:https://doi.org/10.1016/j.matchar.2005.10.004· OSTI ID:20833191

Du, Z W ^[1]; Sun, Z M ^[1]; Shao, B L ^[1]; Zhou, T T ^[2]; Chen, C Q ^[2]

---

1. General Research Institute for Nonferrous Metals, Beijing 100088 (China)
2. School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)

The evolution of microstructure parameters (precipitate size and volume fraction) for an Al-8.0 Zn-2.05 Mg-1.76 Cu alloy during isothermal ageing has been studied by synchrotron-radiation small angle X-ray scattering (SAXS) combining transmission electron microscopy (TEM). The results show that the precipitates are only a few nanometers even at higher temperature 160 deg. C up to 72 h (5.82 nm). The precipitate volume fraction reaches a plateau except ageing at 120 deg. C and the maximum is about 0.052-0.054 in the range 140-160 deg. C. Models describing the evolution of these two parameters with ageing temperature and time have been constructed for our further predicting the precipitate hardening. The coarsening of precipitate is consistent with LSW (Lifshitz-Slyozov-Wagner) model even in the initial stage where volume fraction is still varying. The activation energy of coarsening regime has been determined to be about 1.25 {+-} 0.02 eV.

• OSTI ID: 20833191
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: 2 Vol. 56; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
COPPER ALLOYS
HARDENING
MAGNESIUM ALLOYS
MICROSTRUCTURE
SMALL ANGLE SCATTERING
SYNCHROTRON RADIATION
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ZINC ALLOYS