Distribution and evolution of aging precipitates in Al-Cu-Li alloy with high Li concentration |
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| Authors: | Jin-feng LI Jia-lei HUANG Dan-yang LIU Yong-lai CHEN Xu-hu ZHANG Peng-cheng MA |
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| Affiliation: | 1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;2. Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education, Central South University, Changsha 410083, China;3. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Central South University, Changsha 410083, China;4. Aerospace Research Institute of Materials and Processing Technology, Beijing 100076, China |
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| Abstract: | The evolution and distribution of the aging precipitates in 1460 Al-Li alloy with high Li concentration (2.14%, mass fraction) during T6 aging and two-step T8 (4% predeformation) aging were investigated through TEM. The aging precipitates include δ′ (Al3Li) and T1 (Al2CuLi) phases, of which the δ′ phases are formed first in grain interiors. A lot of δ′/GPI/δ′ composite precipitates in which GPI zones are flanked with a pair of δ′ phases, are formed at 145 °C of T6 aging, which are thermally stable. At 160 °C and 175 °C of T6 aging, many T1 phases nucleate first at subgrain boundaries and grain boundaries, and then form and grow within grains. As to the T8 aging, the δ′/GPI/δ′ composite precipitates are formed during the first-step aging at 130 °C for 20 h, which are thermally stable during the second-step aging at 160 °C. The plastic predeformation accelerates T1 nucleation within grains during the second-step aging at 160 °C. |
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| Keywords: | Al-Li alloy precipitate T6 aging T8 aging aging temperature |
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