2018 Volume 59 Issue 1 Pages 110-116
Binary Al-Mn, ternary Al-Mn-Fe and Al-Mn-Si alloys were prepared by different cooling rates during solidification using direct chill-casting and high-speed twin-roll casting. Mn concentration and solute distribution in Al matrix were examined. The Mn concentration in solid solution was considered almost equivalent in as-cast condition. In contrast, much amount of decomposition of supersaturated Mn in solid solution occurred in high-speed twin-roll cast alloys after homogenization. In high-speed twin-roll cast strips, fine distribution of constituent particles in Al-Mn-Fe alloy and homogeneous solute distribution in Al matrix in Al-Mn-Si alloy were obtained due to the high cooling rate of the high-speed twin-roll casting. After homogenization treatment, coarsening and spheroidization of the constituent particles were mainly observed in Al-Mn-Fe alloy, while formation of fine dispersoids was predominantly observed in Al-Mn-Si alloy. Such differences in microstructure resulted from the decomposition behavior of supersaturated Mn in solid solution.