High-strength Al-Cu-Mg-Ag-Sm alloy was fabricated and subjected to single-stage aging and pre-aging(two-stage aging). Effect of pre-aging on micros tructure and mechanical properties of the alloy was investigated. It ...High-strength Al-Cu-Mg-Ag-Sm alloy was fabricated and subjected to single-stage aging and pre-aging(two-stage aging). Effect of pre-aging on micros tructure and mechanical properties of the alloy was investigated. It is found that the alloy is mainly composed of α-Al, Al_2Cu, Al_2CuMg and AlCu_4Sm. The number of plate-like Ω Al_2Cu precipitates is comparable to that of rod-like S Al_2 CuMg precipitates in the single-stage aged alloy, whereas, in the two-stage aged alloy, it is much higher than that of S precipitates. Q precipitates have a smaller plate thickness and distribute more uniformly in the two-stage aged alloy than in the single-stage aged alloy.Ultimate tensile strength(UTS) and yield strength of the two-stage aged alloy are 12% higher than those of the single-stage aged one, indicating a better aging hardening caused by the two-stage aging. The increased tensile properties mainly come from both stronger precipitation strengthening caused by more Ω precipitates in the twostage aged alloy and stronger solution strengthening from Mg atoms. The fracture surfaces consist of both dimple zones composed of microscale dimples and platform zones composed of nanoscale dimples. The total area of dimple zones for single-stage aged alloy is much higher than that for two-stage aged alloy, which can be attributed to different numbers of Ω precipitates in the two alloys.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51171108)the Open Research Fund of Science and Technology on High Strength Structural Materials Laboratory, Central South University, China
文摘High-strength Al-Cu-Mg-Ag-Sm alloy was fabricated and subjected to single-stage aging and pre-aging(two-stage aging). Effect of pre-aging on micros tructure and mechanical properties of the alloy was investigated. It is found that the alloy is mainly composed of α-Al, Al_2Cu, Al_2CuMg and AlCu_4Sm. The number of plate-like Ω Al_2Cu precipitates is comparable to that of rod-like S Al_2 CuMg precipitates in the single-stage aged alloy, whereas, in the two-stage aged alloy, it is much higher than that of S precipitates. Q precipitates have a smaller plate thickness and distribute more uniformly in the two-stage aged alloy than in the single-stage aged alloy.Ultimate tensile strength(UTS) and yield strength of the two-stage aged alloy are 12% higher than those of the single-stage aged one, indicating a better aging hardening caused by the two-stage aging. The increased tensile properties mainly come from both stronger precipitation strengthening caused by more Ω precipitates in the twostage aged alloy and stronger solution strengthening from Mg atoms. The fracture surfaces consist of both dimple zones composed of microscale dimples and platform zones composed of nanoscale dimples. The total area of dimple zones for single-stage aged alloy is much higher than that for two-stage aged alloy, which can be attributed to different numbers of Ω precipitates in the two alloys.
