Characterization of Second Phase Particles in Twin-Roll Cast Aluminum Alloy AA 8011

A thin strip of 7 mm thickness was manufactured using a twin-roll casting process. Second phase particles were segregated at the center region during the solidification of aluminum alloy AA 8011. Such segregations played a vital role in the formation of pinholes. In the present work, the microstructural analysis was carried out to study the centerline segregation. Fine equiaxed grains were formed at the surface due to the rapid solidification and dynamic recrystallization. An increase in hardness was attributed to centerline segregation of the second phase particles. β-AlFeSi compounds with needle shape morphology were segregated in the thickness range of 10–20 µm parallel to the twin-roll casting direction. Sub-grains were formed inside the elongated grains due to dynamic recovery. Dispersoids were precipitated after the homogenization, which was not found in the as-received twin-roll cast strip.