Effect of Al-Cu alloys diameter on thermal gradient and primary dendrite arm spacing during directional solidification

Directional solidification experiment was carried out on Al-4%Cu(mass fraction) alloy with sample diameters of 4 mm and 7 mm.The results show that the sample with small diameter gets higher thermal gradient,the variation range of temperature gradient is not direct proportional to the ratio of diameters.Thin samples correspond to the smaller cellular and dendrite arm spacing.The variation of primary dendrite arm spacing for 4 mm and 7 mm sample in diameter with growth velocity and the relationship of primary dendrite arm spacing with growing velocity and temperature gradient are obtained.Both relationships agree with the theoretical model.The experimental result fit well with TRIVEDI model.