Retrogression and re-aging (RRA) treatment is adopted for 7B50 aluminum alloy plate. To obtain the parameters of pre-aging process in RRA treatment, the effect of pre-aging process on the microstructural evolution and properties of 7B50 aluminum alloy were systematically investigated via Vickers hardness testing, electrical conductivity measurement, transmission electron microscopy for characterization, and differential scanning calorimetry technique. The results show that pre-aging at 110 ℃ for 16 h, compared to at 120 ℃ for 24 h, can result in the precipitates in the alloy smaller in size and completely redissolved after retrogression process. It is also found that pre-aging at 110 ℃ for 16 h is conducive to the aggregation, growth and complete discontinuity of grain boundary precipitates at elevated temperatures, thus suitable for production engineering of RRA treatment of large-size thick plates.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |