On morphology-dependent growth of secondary dendrite arms: Analysis in peritectic systems

摘要

Although the growth dynamics of secondary branch is essential in determining the final properties of alloys, research on it is rather scarce. Based on a morphology parameter phi which is easily measured to characterize the growth morphology of secondary dendrite arm, the growth behavior of secondary branch which is influenced by its morphology is analyzed in two peritectic systems: Sn-Ni and Sn-Mn. The growth of secondary dendrite arm can be divided into three different types according to phi depending on its growth morphology. An analytical model incorporating phi is established to describe the morphology-dependent growth of secondary branch. Comparison between the experimental data and theoretical predictions on the growth velocity of secondary dendrite arm shows that the morphology parameter phi can well describe the relationship between growth dynamics and the morphology of secondary dendrite arm in different alloys: a smaller phi indicates a larger growth velocity of secondary dendrite arm. (C) 2019 Elsevier B.V. All rights reserved.