Secondary ageing in Al-Cu-Mg
| Autor: | Alfredo Dupasquier, M. Massazza, A. Somoza, Rafael Ferragut, G. Riontino, P. Folegati |
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| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | Philosophical Magazine Letters. 82:495-502 |
| ISSN: | 1362-3036 0950-0839 |
| DOI: | 10.1080/09500830210153896 |
| Popis: | Secondary ageing, that is microstructural evolution occurring at room temperature after short heating at temperatures above the metastable phase boundary of Guinier-Preston zones, has been studied for an Al-Cu-Mg alloy with a high Cu-to-Mg ratio. Combined data from positron annihilation spectroscopy, Vickers microhardness measurements and differential scanning calorimetry show that, on secondary ageing after 5 or 7min at 190°C, firstly, hardening takes place at a rate nine to 16 times slower than natural age hardening; secondly, vacancies slowly released by Cu-rich aggregates formed during the heat treatment at 190°C promote further formation of solute aggregates, with a time-dependent chemical composition; thirdly, the thermal stability of the structures formed during secondary ageing increases with increasing dwell time at room temperature; and, fourthly, solute aggregates formed at 190°C undergo a structural reorganization and possibly a change in the composition, leading to species with a different th... |
| Databáze: | OpenAIRE |
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