Evolution of Fe–rich phases in Mg melt and a novel method for separating Al and Fe from Al–Si–Fe alloys. (15th November 2017)

• Record Type: Journal Article
• Authors: Gao, Tong; Li, Zengqiang; Zhang, Yaoxian; Qin, Jingyu; Liu, Xiangfa
• Is Part Of: Materials & design. Volume 134(2017)
• Page Start: 71
• Page End: 80
• Publication Date: 2017-11-15
• Subjects: Mg melt -- Al–Si–Fe alloys -- Aluminum recycling -- Phase evolution; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2017.08.029
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: The recycling of high Fe–contained Al–Si alloys is a green industry and how to separate Al and Fe is the key point therein. An efficient technique using Mg melt to separate Al and Fe is proposed in this study. By introducing Al–14 wt% Si–4 wt% Fe alloy into Mg melt and adjusting melting, holding and cooling parameters, the evolution behavior and separation performance of Fe–rich intermetallics were investigated. A separation layer with Fe–rich particles was obtained at the bottom of the cooled ingot. A meta–stable phase Fe3 Al0.7 Si0.3 was detected, which only exists above 699 °C confirmed by a thermodynamic calculation. Making β–Al5 SiFe phase from the initial Al–14 wt% Si–4 wt% Fe alloy transform to Fe3 Al0.7 Si0.3 in Mg melt is beneficial to achieve higher separation efficiency since the Fe3 Al0.7 Si0.3 phase is Al–poor, indicating that quantities of Al are released to the Mg matrix. Holding at 750 °C for 30 min followed by a further holding at 650 °C for 30 min is regarded most proper in this study. This work may be referred by relative study on the evolution of intermetallics by introducing one matrix alloy into another melt. Graphical abstract: Highlights: A novel method aiming at recycling Fe–rich Al–Si alloys by introducing them into Mg melt to separate Al and Fe is proposed. β–Al5 SiFe phase in Al–Si–Fe alloys can be designed evolving to Al–poor Fe3 Al0.7 Si0.3 by controlling the melting process. A separation layer rich of Fe can form at bottom while Al is released to the upper melt.