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Al-Cu-Mg-Ag alloys were promising in aircraft applications due to high thermal stability. In this paper, three Al-Cu-Mg-Ag alloys with different components were designed (1#:Al-5.40Cu-0.45Mg-0.98Ag,2#:Al-5.56Cu-0.51Mg-0.99Ag-1.21Fe-0.90Ni,3#:Al-4.96Cu-0.81Mg-0.34Ag), and, by room temperature tensile, high-temperature short-time tensile and thermal exposure, the room temperature mechanical properties and heat resistance of Al-Cu-Mg-Ag alloys were investigated. Mainly to obtain the following conclusions:(1) The optimum homogenization treatment of1#、2#and3#alloys were420℃×6h+495℃×24h、420℃×6h+530℃×24h and420℃×6h+485℃×24h, respectively. The optimum solution treatment of1#、2#and3#alloys were510℃×2h、530℃×3h and510℃×2h, respectively.(2)Ageing at190℃,the peak-aged time of1#、2#and3#alloys were4h、8h and4h, and the peak-aged tensile strength were521MPa、444MPa and526MPa, respectively. The additions of Fe and Ni inhibited the precipitation and growth of the Ω phase, and decreased the age hardening response and peak-aged tensile strength of Al-Cu-Mg-Ag alloy. High Mg content and low Ag content in the3#alloy can promote the precipitation of0’phase, and suppress the precipitation of Ω phase.(3) With the tested temperature arising, the additions of Fe and Ni can increase the stability of the strength of Al-Cu-Mg-Ag alloy. High Mg content and low Ag content were harmful to the high-temperature strength of Al-Cu-Mg-Ag alloy.(4)When exposed at200℃for1000h, the residual strengths of1#.2#and3#alloys were391MPa、374MPa and355MPa, being equal to75.1%、84.2%and67.5%of each peak-aged tensile strength, respectively. When exposed at250℃for1000h, the residual strengths of1#、2#and3#alloys were228MPa、241MPa and255MPa, being equal to43.8%、54.3%and48.5%of each peak-aged tensile strength, respectively. The results of thermal exposure showed that, the additions of Fe and Ni can effectively improve the residual strength of Al-Cu-Mg-Ag alloy.(5) When exposed at200℃, the stability of Q phase was affected by the Cu/Mg ratio of Al-Cu-Mg-Ag alloys. The stability of Ω phase of1#alloy was the best, because of the highest Cu/Mg ratio, and after long time thermal exposure, the microstructure was still dominated by Ω phase. Because of low Cu/Mg ratio, the stability of Ω phase of2#and3#alloys decreased, and some θ’ phase began to precipitate and grow up at the expense of small Ω phases. When exposed at250℃, the Ω phases of1#alloy became unstable, and after500h, the Ω phase was very hard to be observed, with the matrix precipitation dominated by θ(θ’) phase.
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