Effect of Copper Addition on Pitting Corrosion of MA-Al

B. Arandaa, F.G. Cuevasa, J. Cintasb, M. Herrera-Garcíab and P. Urbanb aEscuela Técnica Superior de Ingeniería, University of Huelva, Carretera de Palos s/n, 21819, La Rábida-Huelva, Spain bEscuela Técnica Superior de Ingeniería, University of Seville, Camino de los Descubrimientos s/n, 41092, Sevilla, Spain

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This paper is intended to highlight the effect of copper addition on the pitting corrosion resistance of aluminium-base powder metallurgy parts. Results obtained on these mechanically alloyed (MA) specimens are compared with parts of MA-Al without added copper, as well as with commercial aluminium alloys. Immersion tests from 2 to 96 hours in 3.5% NaCl solutions, and potentiostatic techniques, were used to study the pitting corrosion. It was concluded that copper addition, in a similar way that in commercial aluminium alloys, produces a negative effect on the pitting corrosion resistance, because of the formation of Al2Cu. These precipitates produce galvanic cells that favour the specimen pit. Therefore, increasing the copper content of MA-Al, although improving their ductility, worsens the pitting corrosion resistance of these alloys.

DOI: 10.12693/APhysPolA.129.788 PACS numbers: 81.20.Ev, 82.45.Bb