The Growth of Secondary Dendritic Arms in Directionally Solidified Al-Si-Cu Alloys: A Comparative Study with Binary Al-Si Alloys

Abstract:

Experiments of vertical unsteady-state directional solidification were carried out in order to permit the influence of copper alloying to Al-Si alloys on the scale of secondary dendritic arm (λ₂) to be investigated. The microstructures of Al-nSi-3wt%Cu alloys, with “n” equal to 5.5wt%Si and 9.0wt%Si, were characterized and correlated with solidification thermal parameters: the growth rate (V_L), the tip cooling rate (Ṫ) and the local solidification time (t_SL). A comparative analysis between the present results and those from the literature related to the secondary dendrite growth during directional solidification of Al-nSi alloys is also conducted. It is shown that the addition of Cu to both Al-nSi alloys decreases λ_2, and experimental growth laws relating λ₂ to V_L and Ṫ_L are proposed for the ternary alloys examined. The experimental scatter of λ₂ is also compared with the only theoretical dendritic growth model from the literature for multicomponent alloys, and it is shown that the theoretical predictions overestimate the present experimental results.

• Periodical: Applied Mechanics and Materials (Volumes 719-720)
• Pages: 102-105
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.719-720.102
• Online since: January 2015
• Authors: Laércio G. Gomes, Daniel J. Moutinho, Ivaldo L. Ferreira, Otávio L. Rocha*, Amauri Garcia
• Keywords: Al-Rich Multicomponent Alloys, Microstructural Evolution, Solidification

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