中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 29 No. 1 January 2019 |
（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）
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 d? (Al3Li) and T1 (Al2CuLi) phases, of which the d? phases are formed first in grain interiors. A lot of d?/GPI/d? composite precipitates in which GPI zones are flanked with a pair of d? 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 d?/GPI/d? 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.
Key words: Al-Li alloy; precipitate; T6 aging; T8 aging; aging temperature
