Defects Associated with Nanostructures in AlZnMg and AlCu(Mg) Alloys

• Authors: R. Ferragut
• Languages of publication: EN

Abstracts

EN

The present work reports on a positron annihilation study addressing the structural and chemical characterization of solute aggregates containing open volumes (vacancies and/or misfit regions at precipitate-matrix interfaces) in AlZnMg, AlCu, and AlCuMg alloys. High resolution transmission electron microscopy results for selected ageing conditions are also presented. Two main points are discussed: (i) differentiation of the origin of hardening during artificial ageing between the AlZnMg and AlCu(Mg) alloy systems; (ii) structural origin of secondary ageing at low temperature, after a few minutes of high temperature exposure. It is shown that in AlZnMg alloys hardening at a high temperature is concomitant with the loss of coherency; on the contrary, in AlCu(Mg) alloys hardening is associated with coherent structures. Positron lifetime and coincidence Doppler broadening data taken during secondary ageing indicate that the residual solute supersaturation leads to the formation of coherent Zn-Mg-v (or Cu-Mg-v) aggregates.

Keywords

EN

78.70.Bj; 81.40.Cd

Discipline

• 78.70.Bj: Positron annihilation(for positron states, see 71.60.+z in electronic structure of bulk materials; for positronium chemistry, see 82.30.Gg in physical chemistry and chemical physics)
• 81.40.Cd: Solid solution hardening, precipitation hardening, and dispersion hardening; aging(see also 64.75.Nx Phase separation and segregation in solid solutions)

• Publisher: Institute of Physics, Polish Academy of Sciences
• Journal: Acta Physica Polonica A
• Year: 2005
• Volume: 107
• Issue: 5
• Pages: 776-783

Dates

published

2005-05

received

2004-09-20

Contributors

author

R. Ferragut

• INFM, Dipartimento di Fisica. L-NESS - Politecnico di Milano, Via Anzani 52, 22100 Como, Milano, Italy

References

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Identifiers

DOI

10.12693/APhysPolA.107.776