Effects of different external fields on the microstructure and mechanical properties of novel Al Cu Li alloy during twin-roll casting

The effects of different external fields on the microstructures and properties of twin-roll casting (TRC) 2099 Al-Li alloy sheets as well as their mechanism of action were investigated in detail. The serious central segregation of 2099 Al-Li alloy cast-rolled sheets is due to the unique properties of TRC process such as the high cooling intensity and the wide solidification range of 2099 alloy. The degree of central segregation and dendritic segregation of cast-rolled sheets abates significantly as well as the number of non-equilibrium eutectic phase decreases dramatically under the action of steady static magnetic field, pulse electric field and electromagnetic oscillation field during the TRC process. Especially, the improvement effect of electromagnetic oscillation field is the most remarkable. The electromagnetic stirring force to the mushy zone caused by electromagnetic oscillation field in TRC can not only reduce the temperature gradient and concentration gradient of solute ahead of the crystallizing front but also effectively increase the solute mixing capacity and solid solubility, which reduces the hardness difference along thickness direction and further improves the mechanical properties of the 2099 Al-Li alloy cast-rolled sheets.