Processing of Multi-Layered Al-Al(Sc) Hybrid Sheet by Accumulative Roll Bonding
A high-purity Al alloy and a supersaturated Al-0.3wt.% Sc alloy were accumulative roll bonded (ARB) at 200 °C to generate 0.5 mm gauge sheet consisting of 32 alternating layers of Al and Al(Sc). The material was subsequently annealed for 6h at 350 °C. The deformation and annealed microstructures were investigated using transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD). The deformation microstructure composed primarily of lamellar bands of unequal fineness with shear bands and deformation bands being additional substructural features in the Al(Sc) layers. The high strain deformation generated Al layers containing lamellar boundaries separated by a large fraction of high angle grain boundaries, thereby creating the ideal microstructure for continuous recrystallization. Annealing of the as-deformed material generated a hybrid microstructure consisting of alternating layers consisting of ~20 0m grains produced by continuous recrystallization (Al layers) and a lightly recovered substructure (Al(Sc) layers); the latter were highly resistant to recrystallization due to precipitation of nanosized Al3Sc particles during annealing.
S.-J.L. Kang, M.Y. Huh, N.M. Hwang, H. Homma, K. Ushioda and Y. Ikuhara
M. Z. Quadir et al., "Processing of Multi-Layered Al-Al(Sc) Hybrid Sheet by Accumulative Roll Bonding", Materials Science Forum, Vols. 558-559, pp. 307-312, 2007