Effect of Mg and Si contents and TiC nanoparticles on the center segregation susceptibility of twin-roll cast Al–Mg–Si alloys

Abstract

Center segregation during the twin-roll casting (TRC) has always been a barrier to the fabrication of high-performance Al–Mg–Si strips. In this work, Al–Mg–Si alloys with different Mg and Si contents were fabricated by vertical-type twin-roll caster to investigate the effect of Mg and Si contents on central segregation susceptibility. Alloys that undergo a eutectic reaction to form Si would lead to the enrichment of eutectic Si in the central region due to the low reaction temperature of eutectic Si, resulting the severe central segregation. For alloys with the same eutectic reaction during the solidification, the alloy with higher |ⅆT/ⅆ(fs1/2)| showed agglomeration of the eutectic phases due to its lower solidification rate. For the alloys with the same Mg/Si ratio, the width of central segregation increased with the increase in Mg and Si contents due to the increase in the proportion of near-equiaxed grains in the central region. The introduction of TiC nanoparticles could mitigate the central segregation band due to the control of solute diffusion by the fine near-equiaxed grain structure.