RESPONSE OF AS-CAST AL–ZN–MG–CU ALLOY WITH SC, ZR-ADDITION TO ANNEALING WITH CONSTANT HEATING RATE

1 KODETOVÁ Veronika
Co-authors:
1 VLACH Martin 2 ČÍŽEK Jakub 2 PROCHÁZKA Ivan 1 KUDRNOVÁ Hana 1 LEIBNER Michal
Institutions:
1 Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, CZ-121 16, Prague, Czech Republic, EU, veronika.kodetova@seznam.cz
2 Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00, Prague, Czech Republic, EU
Conference:
27th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, May 23rd - 25th 2018
Proceedings:
Proceedings 27th International Conference on Metallurgy and Materials
Pages:
1582-1586
ISBN:
978-80-87294-84-0
ISSN:
2694-9296
Published:
24th October 2018
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
7 views / 1 download
Abstract

The as-cast Al–Zn–Mg–Cu-based alloy with and without Sc,Zr-addition was studied during isochronal annealing from room temperature up to 480 °C. Precipitation reactions were studied by differential scanning calorimetry and microhardness measurements. These measurements were compared to microstructure development that was observed by scanning electron microscopy. Microstructure observation proved eutectic phase at grain boundaries in the as-cast state of both alloys. The measurements of positron lifetime (LT) spectroscopy confirmed the presence of Guinier-Preston (GP) zones in the initial state of both studied alloys. Neither structure nor volume fraction of eutectic phase shows changes after annealing up to 480 °C. The distinct changes in microhardness curves as well as in heat flow of the alloys studied are mainly caused by dissolution of GP zones and by formation of the particles of the Al–Zn–Mg–Cu system. The apparent activation energy values of the thermal processes were calculated. The hardening effect after isochronal annealing at temperatures above ~ 300 °C reflects the Sc,Zr-addition.

Keywords: Differential scanning calorimetry, hardness Vickers, Al–Zn–Mg–Cu system, Al3(Sc,Zr) phase
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