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Activation of an Al-Zn-Mg-Li alloy by the Presence of Precipitates to be used as Sacrificial Anode

Published online by Cambridge University Press:  21 March 2011

S. Valdez ,
M. A. Talavera ,
J. Genesca  and
J. A. Juarez-Islas
S. Valdez
Affiliation:
Instituto de Investigaciones en Materiales, de Mexico, Circuito Escolar S/N, Cd. Universitaria, 04510, Mexico, D.F. Mexico
M. A. Talavera
Affiliation:
Fac. de Quimica, Universidad Nacional Autonomade Mexico, Circuito Escolar S/N, Cd. Universitaria, 04510, Mexico, D.F. Mexico
J. Genesca
Affiliation:
Fac. de Quimica, Universidad Nacional Autonomade Mexico, Circuito Escolar S/N, Cd. Universitaria, 04510, Mexico, D.F. Mexico
J. A. Juarez-Islas
Affiliation:
Instituto de Investigaciones en Materiales, de Mexico, Circuito Escolar S/N, Cd. Universitaria, 04510, Mexico, D.F. Mexico
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Abstract

This work reports the influence of microstructure on the electrochemical efficiency of Al- alloys to be used as sacrificial anodes. The microstructure of as-cast Al-ingots was characterized by X-ray diffractometry and scanning electron microscope (equipped with WDS microanalysis facilities). The electrochemical behavior was investigated in 3% NaCl solution simulating sea water at room temperature. Regarding microstructure, X-ray diffractometry detected the presence of the α-Al phase, and the τ-Al2Mg3Zn3, Mg7Zn3 and δ-AlLi precipitates. SEM observations confirmed the presence of α-Al dendrites with τ-Al2Mg3Zn3 and Mg7Zn3 particles in matrix. In interdendritic regions, it was observed the presence of the eutectic α-Al + τ-Al2Mg3Zn3 plus some primary Mg7Zn3 particles. δ-AlLi particles were identified at this step only by X-ray diffractometry. Finally, it was detected that an uniform distribution of precipitates in the α-Al dendrites together with an uniform distribution of a fine eutectic gave as a result in as-cast ingots an electrochemical efficiency up to 61.4 %.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 654: Symposia AA – Structure-Property Relationships of Oxide Surfaces & Interfaces , 2000 , AA3.5.1
Copyright
Copyright © Materials Research Society 2001

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