Secondary dendrite growth behavior of intermetallic compound phase during peritectic solidification

Abstract

The growth behaviors of secondary branch are analyzed in both the Sn–Ni and Sn–Mn peritectic systems. The primary and peritectic phases are intermetallic compounds (IMCs) in these two peritectic alloy. In this work, both the growth velocity v tip and growth distance of secondary branch L sec are analyzed. Examination on the experimental results show that v tip decreases with solidification time in a certain sample. Besides, it is found that the growth velocity v tip decreases with the increase of both the pulling velocity of the sample and the temperature gradient in the same peritectic alloy. It is also interesting to find the existence of the range of the growth distance of secondary dendrite arm L sec which gradually increases as solidification proceeds, and then it turns to be stable. The upper and lower limits of L sec have also been determined: μt(ΔT C +ΔT k +ΔT r0 ) 2 ˂ L sec ˂ λ 1 - d , where ΔT C , ΔT k and ΔT r0 are the constitutional undercooling, kinetic undercooling and initial curvature undercooling, respectively. Furthermore, it can be observed that the growth of secondary branches in different peritectic systems is closely related to the solubility range (composition range) of the growing intermetallic compounds (IMCs) phases. It was confirmed that the intermetallic compounds (IMCs) phases with larger solubility range (composition range) has a larger growth velocity. • The growth velocity of secondary branch v tip decreases with solidification time. • v tip decreases as pulling velocity and temperature gradient increases. • A range of the growth distance of secondary dendrite arm L sec exists. • The upper and lower limits of L sec have been determined. • Solid phases with larger solubility range are found to have larger growth velocity.