Non-isothermal aging of a high-Zn-containing Al–Zn–Mg–Cu alloy: microstructure and mechanical properties |
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Authors: | Shabnam Emami Kervee Parnian Pourshayan Farzaneh Nasrollahnezhad Saeed Khani Moghanaki Roland E Logé |
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Affiliation: | 1. Department of Materials Science and Engineering, Sharif University of Technology, Azadi Avenue, Tehran, Iran;2. Thermomechanical Metallurgy laboratory - PX Group Chair, Ecole Polytechnique Fédérale de Lausanne (EPFL), Neuchatel, Switzerland |
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Abstract: | The non-isothermal aging behaviour of a newly developed Al–Zn–Mg–Cu alloy containing 17?wt-% Zn was investigated. Hardness and shear punch tests demonstrated that during non-isothermal aging, the mechanical properties of the alloy first increased and then decreased. The best properties were obtained in a sample which was non-isothermally aged upto 250°C with heating rate of 20°C?min?1, due to the presence of η′/η (MgZn2) phases. This was confirmed by differential scanning calorimetery. After homogenisation, residual eutectic phases remained at triple junctions or in a spherical form. During aging, these phases transformed into rodlike S (Al2CuMg)-phase at 400°C, with sizes ranging from 50 to 250?nm. The precipitation sequence in this high-Zn alloy was similar to that for conventional Al–Zn–Mg–Cu alloys. |
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Keywords: | Al–Zn–Mg–Cu alloy high-Zn non-isothermal aging eutectic phases |
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