The localised corrosion associated with individual second phase particles in AA7075‐T6: A study by SEM, EDX, AES, SKPFM and FIB‐SEM. Issue 7 (30th January 2017)

• Record Type: Journal Article
• Authors: Mallinson, C. F.; Yates, P. M.; Baker, M. A.; Castle, J. E.; Harvey, A.; Watts, Jj F.
• Is Part Of: Materials and corrosion. Volume 68:Issue 7(2017)
• Page Start: 748
• Page End: 763
• Publication Date: 2017-01-30
• Subjects: AES -- aluminium alloy -- intermetallics -- pitting corrosion -- SEM; Materials -- Periodicals; Metals -- Periodicals; Corrosion and anti-corrosives -- Periodicals; 620.1122305
• DOI: 10.1002/maco.201609312
• Languages: English
• ISSNs: 0947-5117

Abstract

Abstract : To investigate the role of intermetallic particles in the localised corrosion of AA7075‐T6, three particles were monitored over 16 h immersion in 3.5 wt% KCl solution. These were examined using Auger electron spectroscopy, energy dispersive X‐ray spectroscopy, scanning Kelvin probe force microscopy and focused ion beam‐scanning electron microscopy. Despite similar Volta potential measurements, the corrosion microchemistry varied significantly with composition. A Al7 Cu2 Fe intermetallic resulted in trenching while a (Al, Cu)6 (Fe, Cu) intermetallic showed crevice corrosion and sub‐surface intergranular corrosion and a Al12 Fe3 Si intermetallic appeared to be galvanically inactive but showed crevice formation at the matrix interface and sub‐surface intergranular corrosion. Abstract : This paper presents the results of a multi technique analysis of the localised corrosion associated with three individual intermetallic particles in AA7075‐T6. The three intermetallics: Al12 Fe3 Si, (Al, Cu)6 (Fe, Cu) and Al7 Cu2 Fe showed a significant increase in the severity of the corrosion process in line with the cathodic current density measured from each individual intermetallics.