Rapid Solidification Characteristics of Highly Undercooled Liquid Ni-Cu-Mo-Ge Quaternary Alloy under Electromagnetic Levitation Condition

Abstract

The dendritic growth characteristics of undercooled liquid Ni-5%Cu-5%Mo-5%Ge quaternary alloy were investigated by electromagnetic levitation method. The measured dendritic growth velocity of α-Ni phase increases with undercooling according to a power law relation, which attains a value of 28 m/s at the maximum undercooling of 321 K (0.19T L). The microstructure morphology appears as coarse dendrites at small undercoolings, while it is refined into equiaxed grains at substantial undercoolings. Furthermore, all the solute elements Cu, Mo and Ge exhibit a significant solute trapping effect during rapid dendritic growth.