Solidification of Iron-Rich Intermetallic Phases in Al-4.5Cu-0.3Fe Cast Alloy

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2011-07, Vol.42 (7), p.2004-2016
• Main Authors: Liu, K., Cao, X., Chen, X.-G.
• Format: Article
• Language: English
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Exact sciences and technology; Iron aluminum alloys; Materials Science; Metallic Materials; Metallurgy; Metals. Metallurgy; Nanotechnology; Structural Materials; Surfaces and Interfaces; Thin Films
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-010-0578-7

The iron-rich intermetallics in A206 type cast aluminum alloy (Al-4.5Cu-0.3Fe) were investigated using thermal analysis, interrupted quenching testing, and differential scanning calorimetry (DSC). An optical microscope with image analysis and scanning electron microscopy were used to identify and quantify the iron-rich intermetallics. Basically, two kinds of iron-rich intermetallics, Chinese script Al 15 (FeMn) 3 (SiCu) 2 ( α -Fe) and platelet Al 7 Cu 2 (FeMn) or Al 7 Cu 2 Fe ( β -Fe), are found in the final microstructures of the A206 cast alloys. All the possible solidification reactions, precipitation temperatures, and nucleation mechanisms for the iron-rich phases were investigated systematically. It is found that both α -Fe and β -Fe phases can precipitate on the oxide films. The α -Fe can also nucleate on Al 6 (FeMnCu) and Al 3 Ti particles. In addition, the previously formed α -Fe phase is also favorable for the nucleation of the β -Fe phase formed subsequently. These nucleation events were not only observed metallographically but also supported by the calculated planar disregistries. A possible nucleation hierarchy has been suggested.