Effect of Mn/Fe ratio on Fe removal efficiency and tensile ductility of an Al–7.0Si–2.4Fe alloy

The poor plasticity of recycled Al–Si alloys severely limits their application owing to the harmful Fe-rich phase. Here we studied the effect of Mn/Fe mass ratio on iron removal efficiency and type of iron-rich phase in Al–7.0Si–2.4Fe alloy. The results show that adding Mn promotes the formation of...

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Bibliographic Details
Published in:Journal of materials research 2021-03, Vol.36 (6), p.1357-1366
Main Authors: Song, Dongfu, Zhao, Yuliang, Wang, Zhi, Jia, Yiwang, Huang, Huilan, Zhang, Datong, Zhang, Weiwen
Format: Article
Language:English
Subjects:
Alloys
Aluminum base alloys
Applied and Technical Physics
Biomaterials
Casting alloys
Chemical composition
Chemistry and Materials Science
Crack initiation
Crack propagation
Efficiency
Elongation
Fracture strength
Ingot casting
Inorganic Chemistry
Iron
Manganese
Materials Engineering
Materials research
Materials Science
Mechanical properties
Morphology
Nanotechnology
Phases
Ratios
Shape
Silicon
Sludge
Solidification
Tensile properties
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Summary:The poor plasticity of recycled Al–Si alloys severely limits their application owing to the harmful Fe-rich phase. Here we studied the effect of Mn/Fe mass ratio on iron removal efficiency and type of iron-rich phase in Al–7.0Si–2.4Fe alloy. The results show that adding Mn promotes the formation of primary α-Al 15 (FeMn) 3 Si 2 rather than α-Al 8 Fe 2 Si, benefit for the gravity sedimentation and removal of sludge phases owing to the higher formation temperature of α-Al 15 (FeMn) 3 Si 2 . When Mn/Fe ratio is higher than 0.7, a peritectic structure forms showing irregular double-layer band-shape with high Mn/Fe ratio in inner layer, whose volume fraction and size gradually increase with increasing Mn/Fe ratio. The peritectic structures consumed the Mn in the melt, leading to no more increase of Fe removal efficiency. The remaining Mn transforms the needle-like β-Al 5 FeSi to compact α-Al 15 (FeMn) 3 Si 2 . Both fracture strength and elongation improved significantly compared with the alloy without Mn addition, while mechanical properties have no obviously change with increasing Mn/Fe ratio. Graphic abstract There are 10 pictures in this manuscript, the abstracts are listed as follows: Fig.  1 shows the effect of Mn/Fe ratio on the chemical composition of the ingots; Fig.  2 shows the morphologies, chemical composition of the sludge phases in the slag with different Mn/Fe ratios; Fig.  3 shows equilibrium solidification curves with different Mn/Fe ratios; Fig.  4 shows the morphological statistics of the two kinds of typical sludge phases under different Mn/Fe ratios; Fig.  5 shows the effect of sphericity and equivalent diameter on settlement velocity; Fig.  6 shows the microstructure of the Al–7Si–2.4Fe alloy after melt holding under different Mn/Fe ratios; Fig.  7 shows the XRD and DSC curves after melt holding under different Mn/Fe ratios; Fig.  8 shows the morphological characteristics of Fe-rich phases in different spatial directions; Fig.  9 shows the tensile properties of the as-cast alloy with different Mn/Fe ratios; Fig.  10 shows the cracks initiation and propagation of the as-cast alloy with different Mn/Fe ratios.
ISSN:0884-2914
2044-5326
DOI:10.1557/s43578-021-00194-6