Interactions between cadmium and multiple precipitates in an Al-Li-Cu alloy: Improving aging kinetics and precipitation hardening
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2020年第11期
论文作者：Liang Wu Yugang Li Xianfeng Li Naiheng Ma Haowei Wang
文章页码：44 - 49
摘 要：This work demonstrates significant improvements in both the aging kinetics and precipitation hardening of an Al-Li-Cu alloy with the minor addition of Cd（0.06 at.%）. The precipitation hardening effect of T1 precipitates in casting Al-Li-Cu alloys has long been ignored since it is difficult to achieve a high number density of fine precipitates without a large number of dislocations. A detailed transmission electron microscopy investigation shows that the Cd addition has changed the distribution of T1 precipitates from the conventional uneven distribution near dislocations or grain boundaries to a more homogeneous manner. Most of the Cd-rich nanoparticles were observed at the broad face and/or terminal of the T1 platelets. It is highly likely that these nanoparticles act as heterogeneous nucleation sites, which consequently leads to a higher number density of T1 precipitates. Moreover, Cd atoms were preferentially segregated within ? precipitates, which can be attributed to the strong bonding between Li and Cd. The interactions between Cd and the T1（Al2CuLi） and ?（Al3Li） precipitates in Al-Li-Cu alloy are first reported. The present study may propose a new mechanism to effectively improve precipitation kinetics and therefore the age-hardening effect of Al-Li-Cu alloys.
Liang Wu1,2，Yugang Li2，Xianfeng Li1，Naiheng Ma1,2，Haowei Wang1,2
1. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University2. School of Materials Science and Engineering, Shanghai Jiao Tong University
摘 要：This work demonstrates significant improvements in both the aging kinetics and precipitation hardening of an Al-Li-Cu alloy with the minor addition of Cd（0.06 at.%）. The precipitation hardening effect of T1 precipitates in casting Al-Li-Cu alloys has long been ignored since it is difficult to achieve a high number density of fine precipitates without a large number of dislocations. A detailed transmission electron microscopy investigation shows that the Cd addition has changed the distribution of T1 precipitates from the conventional uneven distribution near dislocations or grain boundaries to a more homogeneous manner. Most of the Cd-rich nanoparticles were observed at the broad face and/or terminal of the T1 platelets. It is highly likely that these nanoparticles act as heterogeneous nucleation sites, which consequently leads to a higher number density of T1 precipitates. Moreover, Cd atoms were preferentially segregated within ? precipitates, which can be attributed to the strong bonding between Li and Cd. The interactions between Cd and the T1（Al2CuLi） and ?（Al3Li） precipitates in Al-Li-Cu alloy are first reported. The present study may propose a new mechanism to effectively improve precipitation kinetics and therefore the age-hardening effect of Al-Li-Cu alloys.
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