Assessment of different techniques for quantification of α-Al(FeMn)Si and β-AlFeSi intermetallics in AA 6xxx alloys

• Published in: Materials characterization Vol. 49; no. 5; pp. 409 - 420
• Main Authors: Kuijpers, N.C.W., Kool, W.H., Koenis, P.T.G., Nilsen, K.E., Todd, I., van der Zwaag, S.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.12.2002; Elsevier Science
• Subjects: Aluminium alloy; Applied sciences; Characterisation; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Intermetallics; Materials science; Metals. Metallurgy; Phase transformation; Physics; Solid solution hardening, precipitation hardening, and dispersion hardening; aging; Solid solution, precipitation, and dispersion hardening; aging; Treatment of materials and its effects on microstructure and properties; Intermetallics; Phase transformation; Aluminium alloy; Characterisation; Magnesium additions; Scanning electron microscopy; Aluminium base alloys; Intermetallic compounds; Phase transformations; Homogenization; XRD; Experimental study; Dispersive spectrometry; Precipitates; Heat treatments; Silicon additions; Characterization; Iron additions
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/S1044-5803(03)00036-6

During homogenisation of AA 6xxx aluminium alloys, the platelike β-AlFeSi intermetallic phase will transform to a less Si-rich and more spheroidised α-Al(FeMn)Si phase which is more favourable for extrusion. In this study, several quantitative methods, which determine the relative volume fraction of α-Al(FeMn)Si and β-AlFeSi, are compared and an assessment of each method is made. The methods used are optical microscopy, scanning electron microscopy (SEM) in combination with electron dispersive X-ray (EDX) using polished samples, and X-ray diffraction (XRD) on intermetallics, extracted through selective dissolution of the Al matrix. The highest accuracy is obtained by using SEM/EDX analysis and applying two criteria.