Micro-segregation of Primary Si in ADC14 (Al–17Si–4Cu) Alloy Produced by Unidirectional Continuous Casting

An upgrading approach for hypereutectic Al–Si alloys was investigated through controlled segregation of Si using a unidirectional casting process. The precipitation behavior and spatial distribution of primary Si in the hypereutectic ADC14 (Al–17Si–4Cu) alloy were systematically examined at different casting speeds (0.06, 1.9, and 10 mm/s). Microstructural observations revealed that high casting speed suppresses primary Si formation due to rapid solidification, whereas intermediate speed leads to a relatively uniform distribution of primary Si. In contrast, low casting speed combined with a holding period for 2 min promotes pronounced segregation and coarsening of primary Si in localized regions. Energy-dispersive X-ray spectroscopy analysis confirmed significant fluctuations in Si concentration along the casting direction, particularly after process interruption. Based on these results, a preliminary upgrading process was proposed, involving the selective removal of Si-enriched regions followed by remelting. This approach resulted in a reduction of Si content to approximately 13.9 wt.%, corresponding to a decrease of about 3%. The results demonstrate that controlling solidification behavior to induce phase separation provides a promising and energy-efficient strategy for upgrading recycled Al–Si alloys.

This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: http://dx.doi.org/10.1007/s40962-026-02100-4

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