Influence of homogenization treatment on microstructure and recrystallization behavior of 2195 Al-Li alloy
(1. School of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
2. State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha 410083, China;
3. Research Institute of Light Alloy, Central South University, Changsha 410083, China)
2. State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha 410083, China;
3. Research Institute of Light Alloy, Central South University, Changsha 410083, China)
Abstract: The microstructural evolution during homogenization treatment and the recrystallization behavior caused by Al3Zr precipitate in 2195 alloy were investigated via scanning electron microscopy, X-ray diffraction, transmission electron microscopy and electron backscatter diffraction. The severe dendrite segregation in the as-cast alloy was removed during homogenization, but the process was limited by the slower dissolution of Al-Cu phases. Moreover, the Al3Zr dispersoids precipitated in the sample homogenized by ramp heating rate of 30 ℃/h (H30) were finer and denser compared to the samples subjected to other homogenization treatments (single-step, double-step, and ramp heating rate of 60 ℃/h). The movement of dislocations and (sub)grain boundaries was resisted by the stronger Zener drag of finer and denser Al3Zr dispersoids. Thus, a higher recrystallization resistance during the hot compression and subsequent solution treatment was achieved for H30 sample. This work can provide theoretical guidance for optimizing the heat treatment parameters of the as-cast 2195 Al alloy.
Key words: Al-Cu-Li alloy; homogenization; Al-Cu phase dissolution; Al3Zr precipitate; recrystallization