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Open AccessArticle

Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content

Department of Materials Science and Engineering, University of Ioannina, Ioannina 45110, Greece
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Academic Editors: Vineet V. Joshi and Alan Meier
Metals 2016, 6(3), 46; https://doi.org/10.3390/met6030046
Received: 18 January 2016 / Revised: 11 February 2016 / Accepted: 19 February 2016 / Published: 27 February 2016
(This article belongs to the Special Issue Oxidation of Metals)
Hypereutectic Al-Co alloys of various Co contents (7–20 weight % (wt.%) Co) were prepared by vacuum arc melting, aiming at investigating the influence of the cobalt content on the microstructure and corrosion behavior. Quite uniform and directional microstructures were attained. The obtained microstructures depended on the Co content, ranging from fully eutectic growth (7 wt.% and 10 wt.% Co) to coarse primary Al9Co2 predominance (20 wt.% Co). Co dissolution in Al far exceeded the negligible equilibrium solubility of Co in Al; however, it was hardly uniform. By increasing the cobalt content, the fraction and coarseness of Al9Co2, the content of Co dissolved in the Al matrix, and the hardness and porosity of the alloy increased. All alloys exhibited similar corrosion behavior in 3.5 wt.% NaCl with high resistance to localized corrosion. Al-7 wt.% Co showed slightly superior corrosion resistance than the other compositions in terms of relatively low corrosion rate, relatively low passivation current density and scarcity of stress corrosion cracking indications. All Al-Co compositions demonstrated substantially higher resistance to localized corrosion than commercially pure Al produced by casting, cold rolling and arc melting. A corrosion mechanism was formulated. Surface films were identified. View Full-Text
Keywords: Al-Co alloys; hypereutectic; Al9Co2; complex metallic alloys; vacuum arc melting; directional growth; aqueous corrosion; reverse polarization; pseudo-passivation; Raman spectroscopy Al-Co alloys; hypereutectic; Al9Co2; complex metallic alloys; vacuum arc melting; directional growth; aqueous corrosion; reverse polarization; pseudo-passivation; Raman spectroscopy
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MDPI and ACS Style

Lekatou, A.; Sfikas, A.K.; Petsa, C.; Karantzalis, A.E. Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content. Metals 2016, 6, 46. https://doi.org/10.3390/met6030046

AMA Style

Lekatou A, Sfikas AK, Petsa C, Karantzalis AE. Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content. Metals. 2016; 6(3):46. https://doi.org/10.3390/met6030046

Chicago/Turabian Style

Lekatou, Angeliki; Sfikas, Athanasios K.; Petsa, Christina; Karantzalis, Alexandros E. 2016. "Al-Co Alloys Prepared by Vacuum Arc Melting: Correlating Microstructure Evolution and Aqueous Corrosion Behavior with Co Content" Metals 6, no. 3: 46. https://doi.org/10.3390/met6030046

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