Improvement of strength and ductility of Al-Cu-Li alloy through cryogenic rolling followed by aging
(College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China)
Abstract: To develop an improved approach in achieving an excellent combination of high strength and ductility, the solutionized Al-Cu-Li plates were subjected to rolling at cryogenic and room temperatures, respectively, to a reduction of 83%, followed by aging treatment at 160 °C. The results indicate that Al-Cu-Li alloys through cryogenic rolling followed by aging treatment possess better mechanical properties. Rolling at cryogenic temperature produces a high density of dislocations because of the suppression of dynamic recovery, which in turn promotes the precipitation of T1 (Al2CuLi) precipitates during aging. Such high density of T1 precipitates enable effective dislocation pinning, leading to an increase in strength and ductility. In contrast, room temperature rolled alloys after aging treatment exhibit lower strength and ductility due to low density of T1 precipitates in the grain interior and high density of T1 precipitates around subgrain boundaries.
Key words: Al-Cu-Li alloy; cryogenic rolling; dislocation; T1 precipitate