Electrochemical Properties of Diluted Al-Mg Alloys With Columnar-To-Equiaxed Transition

MÉNDEZ, CLAUDIA MARCELA; ZADOROZNE, NATALIA SILVINA; IBAÑEZ, EDGAR ROLANDO; KRAMER, GUSTAVO RAÚL; ARES, ALICIA ESTHER; ROMÁN, ALEJANDRA SILVINA; PEDROZO, MARIANELA; ALONSO, PAULA REGINA

Frontiers in Materials

Frontiers Media S.A.

Lugar: Lausana; Año: 2022 vol. 9

The objective of the present research is to study the corrosion susceptibility of two Al-Mg diluted alloys (Al-0.5wt.%Mg and Al-2wt.%Mg) with different grains structuresobtained by directional solidification (columnar, equiaxed and columnar-to-equiaxedtransition, CET) in 0.5% NaCl solution, at room temperature. The corrosion resistanceis analyzed by potentiodynamic polarization and electrochemical impedancespectroscopy (EIS) techniques in both longitudinal and transversal sections of thesamples. The columnar grain zone presents higher corrosion resistance than theequiaxed grain zone. In addition, the transversal section shows higher corrosionresistance than the longitudinal section of the samples. Then, the Al-0.5wt.% Mgalloy displays higher corrosion resistance than the Al-2wt.% Mg alloy. The values of thepolarization resistance are used as a basic criterion for the evaluation of the corrosionresistance of both alloys. In this way, when the polarization resistance decreases withthe increasing in the distance from the base, the grain size, secondary dendritic armspacings and hardness increases. In addition, when the polarization resistanceincreases, the critical temperature gradient decreases.