PRECIPITATION HARDENING IN AS-CAST AA6082 AND AA5754 COMMERCIAL ALLOYS WITH SC, ZR-ADDITION

1 LEIBNER Michal
Co-authors:
1 VLACH Martin 1 KODETOVÁ Veronika 1 SMOLA Bohumil 1 VLČEK Marián 1 KEKULE Tomáš 1 PROCHÁZKA Ivan 1 KUDRNOVÁ Hana 2 OČENÁŠEK Vladivoj
Institutions:
1 Charles University, Faculty of Mathematics and Physics, Ke Karlovu 3, CZ-121 16, Prague, Czech Republic, EU, mleibner@seznam.cz
2 SVÚM a.s., Tovární 2053, CZ-250 88, Čelákovice, 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:
1605-1610
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:
16 views / 1 download
Abstract

The as-cast AA5754 and AA6082 alloys with Sc,Zr-addition were investigated during isochronal annealing from room temperature up to 510 °C. Precipitation reactions were studied by electrical resistivity, hardness measurements and differential scanning calorimetry. The measurements were compared to microstructure development that was observed by transmission electron microscopy. Higher initial resistivity as well as hardness values are probably caused by a higher content of the solutes in the AA5754-ScZr alloy in comparison with the latter alloy. Both alloys contains spherical particles of the Al3(Sc,Zr) phase in the as-cast state. Moreover, the AA6082-ScZr alloy contains Mg,Si,Sc-containing phase at grain boundaries and rods/needles of the Mn,(Fe)-containing phase. The transient Al–Mg–Si-phase (β’’ and/or β’) particles formed during isochronal annealing in the AA6082-ScZr alloy cause a poor age hardening. The additional Al3(Sc,Zr) particles precipitation causes a pronounced hardening in the AA5754-ScZr alloy. The possible (weak) additional precipitation of the Al3(Sc,Zr) particles in the AA6082-ScZr alloy has a lower effect on hardness than the precipitation of β’’ and β’ phases or Sc and Zr solutes are probably bound in the Al3(Sc,Zr) particles and do not influence precipitation hardening in the course of isochronal annealing in the AA6082 alloy. The precipitation of the Al6(Mn,Fe)-phase was observed in the alloys during the isochronal heat treatment. The apparent activation energy values of precipitation of the transient β’’ and/or β’ phases, Al6(Mn,Fe)-phase and Al3(Sc,Zr) phase were determined.

Keywords: Electrical resistivity, DSC, TEM, Al–Mg–Si system, Al3(Sc,Zr) phase
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