アルミニウム合金のデンドライト凝固におけるミクロ偏析

抄録

The minimum solute concentration in dendrite arms and the amount of non-equilibrium eutectic phase were measured in Al-4.5% Cu and Al-6.3 and 10.4% Mg alloys uni- and non-directionally solidified. When the alloys are unidirectionally solidified and arrayed columnar dendrites grow, the minimum solute concentration is high at the initial stage of solidification and the solute remarkably condenses at the center and the growing interface of the arms during solidification. The arms grow being accompanied with a solute-enriched layer in the liquid and with a steep concentration gradient in the arms. If cooling is accelerated and the effective distribution coefficient is increased, the minimum solute concentration increases and the amount of non-equilibrium eutectic decreases. When the alloys are non-directionally solidified and equiaxed dendrites grow, nearly the opposite phenomena are encountered.