Jiang Dandan, Yang Ruibin, Wang Defa, Liu Zhongxia
Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, Henan Province, 450052, China.
School of Basic Science, Zhengzhou University of Technology, Zhengzhou, Henan Province, 450052, China.
Micron. 2021 Apr;143:103011. doi: 10.1016/j.micron.2021.103011. Epub 2021 Jan 22.
The effects of external stress on the precipitation of T precipitates and mechanical properties of creep-aged Al-Cu-Li-Ag alloys are investigated. Promotion mechanisms of external stress to the precipitation of T precipitates are discussed. It is found that external stress significantly promotes the precipitation and improves the distribution of the T precipitates in the creep-aged alloys. There is a threshold stress, close to the yield stress, that has only a limited promotion effect on the precipitation of T precipitates. The external stress below and above the threshold stress promotes the precipitation of T precipitates by two different mechanisms. One is the promotion mechanism of lattice distortion produced by the elastic stress. Another is the promotion mechanism of multiplication of dislocations produced by the plastic stress. Both elastic and plastic external stress can synergistically improve the strength and ductility. Especially, the plastic external stress resulted in the best improvement to ductility of creep-aged alloys. Hence, the creep ageing with plastic external stress is an alternative method to synergistically improve the strength and ductility of Al-Cu-Li-Ag alloys. However, it is necessary to avoid using excessive plastic stress for the creep ageing because it may cause creep damage and degrade its mechanical properties.
研究了外部应力对T相析出及蠕变时效Al-Cu-Li-Ag合金力学性能的影响。讨论了外部应力促进T相析出的机制。结果表明，外部应力显著促进了T相的析出，并改善了其在蠕变时效合金中的分布。存在一个接近屈服应力的阈值应力，该应力对T相析出的促进作用有限。阈值应力以下和以上的外部应力通过两种不同机制促进T相析出。一种是弹性应力产生的晶格畸变促进机制。另一种是塑性应力产生的位错增殖促进机制。弹性和塑性外部应力均可协同提高强度和延展性。特别是，塑性外部应力对蠕变时效合金的延展性改善效果最佳。因此，塑性外部应力作用下的蠕变时效是协同提高Al-Cu-Li-Ag合金强度和延展性的一种替代方法。然而，蠕变时效时必须避免使用过大的塑性应力，因为这可能会导致蠕变损伤并降低其力学性能。
