Positron-annihilation study of the aging kinetics of AlCu-based alloys. I. Al-Cu-Mg

A. Somoza, A. Dupasquier, I. J. Polmear, P. Folegati, and R. Ferragut
Phys. Rev. B 61, 14454 – Published 1 June 2000
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Abstract

Positron-annihilation spectroscopy has been applied for studying the aging kinetics and the association of vacancies to solute elements during precipitation in an Al-Cu-Mg alloy with high Cu/Mg ratio. The results show that: (i) isolated vacancies–Mg complexes exist in the alloy following quenching from the solution treatment temperature; (ii) after aging at temperatures below 68 °C, the vacancies are associated with Cu and with Cu-Mg aggregates [solute clusters, Guinier-Preston GP(Cu) and GP(Cu, Mg) zones]; (iii) the contribution of Cu-Mg aggregates decreases as the aging temperature is raised from 20 to 68 °C; (iv) immediately after aging at 180 °C for times from 15 s to 10 h, the vacancies are present only in pure Cu regions, but vacancies in Cu-Mg aggregates become observable when the sample is cooled and aged at room temperature. The kinetics of formation of solute aggregates can be described, after scaling, by a temperature-independent function. From the temperature dependence of the scaling factors, an effective activation energy of 0.65 eV was obtained.

  • Received 31 August 1999

DOI:https://doi.org/10.1103/PhysRevB.61.14454

©2000 American Physical Society

Authors & Affiliations

A. Somoza

  • IFIMAT-UNCentro and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil, Argentina

A. Dupasquier

  • Instituto Nazionale di Fisica della Materia and Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy

I. J. Polmear

  • Monash University, Department of Materials Engineering, Clayton, Victoria 3168, Australia

P. Folegati

  • Instituto Nazionale di Fisica della Materia and Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy

R. Ferragut

  • IFIMAT-UNCentro and Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, Pinto 399, 7000 Tandil, Argentina

See Also

Positron-annihilation study of the aging kinetics of AlCu-based alloys. II. Ag microalloying

A. Somoza, A. Dupasquier, I. J. Polmear, P. Folegati, and R. Ferragut
Phys. Rev. B 61, 14464 (2000)

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Vol. 61, Iss. 21 — 1 June 2000

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