The present work underlines the influence of phase transformations on the electrochemical behaviour of Al-Ga binary alloys and Al-Zn-Ga ternary alloys used as sacrificial anodes. A study of the Al-Zn-Ga ternary phase diagram was conducted to find stable and metastable equilibria. Knowledge of these equilibria permitted the definition of the thermal treatments which govern, at room temperature, the existence (or otherwise) of a gallium rich liquid phase in the alloys. More significant depassivation was observed when the thermodynamic data indicated that gallium was in the liquid state. For these alloys, a correlation between electrochemical depassivation and the phase diagram was established.
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References
1.
MassalskiT. B.: in ‘Binary alloy phase diagrams’, (ed. MassalskiB.), 2nd edn, 149; 1992, Materials Park, OH, ASM International.
2.
AnsaraI.: in ‘Ternary alloys’, Vol. 5, (ed. PetzowG. and EffenbergG.), 552; 1991, Weinheim, VCH.
3.
AragonE.: ‘Study of aluminium alloys used for the cathodic protection of structures in seawater’, thesis, Université de Toulon et du Var, La Garde, France, 1995.
4.
EvansS. and KoehlerE. L.: J. Electrochem. Soc., 1961, 108, (6), 509.
5.
GimenezP.: ‘Influence de l'indium sur la dépassivation de l'aluminium’, thesis, Université Scientifique et Médicale et INP de Grenoble, Grenoble, France, 1982.
6.
ReboulM. and DelatteM.: Rev. Alum., 1981, 511, 417.
7.
DespicA. R., DrazicD. M., PURENOVICM. M., and CIROVICN.: J. Appl. Electrochem., 1976, 6, 527.
8.
BreslinC. B. and CarollW. M.: Corros. Sci., 1992, 33, 1735.
9.
TuckC. D. S., HunterJ. A., and SCAMANSG. M.: J. Electrochem. Soc., 1976, 134, 446.
