Mechanical properties and thermal stability of 7055 Al alloy by minor Sc addition
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This study investigated the effect of 0.25 wt% Sc addition on the microstructure and mechanical properties of AA 7055 alloy. The addition of Sc obviously refined the grains of AA 7055 alloy during casting, homogenizing, rolling, solution, and aging treatments due to the formation of primary and precipitate Al3(Sc,Zr) phase. The recrystallization and precipitation of AA 7055 alloy were inhibited during heat treatments by Sc addition. The Sc-containing AA 7055 alloy exhibited higher thermal stability than AA 7055 alloy during homogenizing treatment, because of the grain boundary pinning effect of nano-sized Al3(Sc,Zr) particles. Given its structure characteristics such as fine grains, fine η′ phase, and less η phase, AA 7055 alloy with added Sc showed good mechanical properties after aging at 120 °C for 24 h, with an ultimate tensile strength (UTS) of 679 MPa and elongation (EL) of 14%. This work provides an effective strategy to fabricate Al–Zn–Mg(–Cu) series (7xxx) alloys with excellent mechanical properties.
KeywordsAl alloy Sc addition Microstructure Mechanical properties
This work was financially supported by the National Natural Science Foundation of China (No. 51601045), the Research Program of Science and Technology of Guangxi (No. GKAB16380021) and the Guangxi “Bagui” Teams for Innovation and Research.
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