Microstructure evolution and mechanical properties of Al-3.6Cu-1Li alloy via cryorolling and aging
(1. State Key Laboratory of High Performance Complex Manufacturing, Central South University, Changsha 410083, China;
2. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
3. Research Center for Advanced Science and Technology, The University of Tokyo, Meguro, Tokyo 1530041, Japan;
4. Electron Microscope Unit, University of New South Wales, Sydney, NSW 2052, Australia;
5. Light Alloys Research Institute, Central South University, Changsha 410083, China)
2. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
3. Research Center for Advanced Science and Technology, The University of Tokyo, Meguro, Tokyo 1530041, Japan;
4. Electron Microscope Unit, University of New South Wales, Sydney, NSW 2052, Australia;
5. Light Alloys Research Institute, Central South University, Changsha 410083, China)
Abstract: An Al-3.6Cu-1Li alloy was subjected to room temperature rolling and cryorolling to investigate their effects on microstructure evolution and mechanical properties. The microstructure and aging characteristics of the room temperature-rolled and the cryorolled alloys with 70% and 90% of thickness reductions were studied by microstructure analysis and mechanical tests. The samples subjected to cryorolling with 90% of thickness reduction have high strength and good toughness. This is mainly due to the inhibition of dynamic recovery and the accumulation of high-density dislocations in cryorolled samples. In addition, the artificial aging reveals that the temperature at which peak hardness is attained is inversely proportional to the deformation amount and directly proportional to the rolling temperature. Moreover, bright field images of cryorolled samples after aging indicate the existence of T1 (Al2CuLi) precipitates. This suggests that the high stored strain energy enhances the aging kinetics of the alloy, which further promotes the nucleation of T1 phases.
Key words: Al-Cu-Li alloy; cryorolling; aging; precipitation strengthening; mechanical property