CORROSION RESISTANCE OF DENDRITIC AND EUTECTIC AL-CU ALLOYS AS A FUNCTION OF MICROSTRUCTURE

ALICIA E. ARES; CLAUDIA M. MENDEZ; LILIANA M. GASSA

Cancún

Conferencia; 3º COLLABORATIVE CONFERENCE ON CRYSTAL GROWTH (3CG); 2013

International Union of Crystal Growth (3CG)

Commercial Aluminum alloys often contain Cu, Mn, Mg, Si, Zn and Li in varying proportions between 0.1 and 10 %. These alloys are widely used in components of transportation due to fuel savings associated with weight reduction benefits similar security without compromising the safety of the occupants. Some of most widely used aluminum alloys are those containing between 4 and 10 wt.% Cu. Metallurgical factors that may affect the corrosion of an alloy include: crystallography, size, shape and heterogeneity of the grain, impurities, inclusions and residual stresses. [1,2] In the present research, in order to analyze the corrosion resistance of Al-Cu alloys directionally solidified, all electrochemical tests were conducted in a 3% NaCl 300 ml solution at room temperature using an IM6d ZAHNER® electrik potentiostat coupled to a frequency analyzer system, a glass corrosion cell kit with a platinum counter electrode and a sutured calomel reference electrode (SCE), see Figures 1 (j) and (k) show the detail of the experimental arrangement. Polarization curves were obtained using a scanning rate in the range of 0.002 V/s £  v £ - 0.250 V/s from open circuit potential until to 0.250 V.  Impedance spectrums were registered in the frequency range of 10-3 Hz  £  f £  105 Hz in open circuit. The corrosion susceptibility depends on the formation of a thick film of oxide as revealed by the electrochemical impedance spectroscopy (EIS) analysis. However, the presence of Copper in their composition makes them susceptible to pitting corrosion. The least susceptible Al-Cu alloys are those containing 10wt.% Cu in its composition. The most influencing microstructural variable for corrosion resistance has been found to be the secondary dendrite arm spacing (SDAS).  It has been found that resistance decreases with SDAS.