Modeling dendrite growth in undercooled concentrated multi-component alloys

• Published in: Acta materialia Vol. 61; no. 11; pp. 4254 - 4265
• Main Authors: Wang, Kang, Wang, Haifeng, Liu, Feng, Zhai, Haimin
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-06-2013; Elsevier
• Subjects: Applied sciences; Concentrated; Dendrite growth; Exact sciences and technology; Metals. Metallurgy; Multi-component; Rapid solidification; Rapid solidification; Concentrated; Multi-component; Dendrite growth; Microstructure; Modeling; Dendrite
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2013.03.051

Most theoretical work on dendrite growth has focused on dilute binary alloys, while most industrial alloys are concentrated multi-component systems. By incorporating the local non-equilibrium effects both at the interface and in the bulk liquid, the thermodynamic database and diffusional interaction, a model was developed for dendrite growth in undercooled concentrated multi-component alloys. An experimental study of dendrite growth in undercooled Ni–18at.% Cu–18at.% Co melts was carried out and the measured interface velocities (V) were well predicted by the present model over the whole undercooling range (ΔT=30–313K). During dendrite growth the partition coefficients change non-monotonically due to interaction between the species and changes in the dendrite tip radius. Interaction between the species also leads to a lower interface velocity and larger ΔT and V as the ΔT–V relation plateaus. The previous definition of constitutional undercooling, i.e. the sum of the contributions of each solute, is not applicable to concentrated multi-component alloys. The controlling mechanisms during dendrite growth are discussed with respect to the results of the calculations.