1 College of Materials Science and Engineering, Hunan University, Changsha 410082, China 2 Beijing Institute of Aeronautical Materials, Beijing 100095, China
The influence of heat treatment on microstructure, mechanical properties and intergranular corrosion(IGC) of 7A85 aluminum alloy was investigated by tensile testing, conductivity testing, intergranular corrosion testing and transmission electron microscope. The results show that tensile strength, elongation and conductivity of 7A85 aluminium alloy aged at 120℃/24h are 760.8MPa, 8.9% and 29.7%IACS respectively;the main strengthening precipitates in the alloy are GP zones.While the tensile strength and the conductivity of 7A85 aluminium alloy reach 597.7MPa and 38.1%IACS respectively, after duplex aging at 120℃/8h+165℃/12h, and with increase of aging time, the precipitates in the matrix become coarser and PFZs become broaden, resulting in the susceptibility to IGC decreasing. Therefore, the alloy after duplex aging at 120℃/8h+165℃/12h shows good comprehensive performance.
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