Effect of Solidification Structure of the Alloy Cu-10% Al-1% Fe on Its Corrosion and Mechanical Properties

An 89% Cu, 10% Al, 1% Fe alloy was solidified under different cooling conditions in order to obtain different kinds of dendritic structures. The main structural difference observed was the grain size, which varied from 0.017 to 0.57 grains/mm². The mechanical behavior was determined by tension and hardness test. The fracture surface and microstructure were observed by means of scanning electron microscopy. Other samples were subjected to corrosion tests in a saline solution of a concentration similar to that of seawater; these tests were potentiodynamic and potentiostatic during twelve hours at −50 mV (ECS). The electrolytic solutions were analyzed by atomic absorption spectrophotometry to determine the Cu, Al, and Fe concentrations.

The tension and hardness tests did not show a significant correlation. The corrosion tests showed a different amount of corrosion, which depends primarily on the morphology and type of solidification structure. Higher dealuminization was found in samples with higher content of γ₂ phase. The columnar grain structure showed a lower selective corrosion than the equiaxial structure.

A fine dispersion of the α + β phase in relation to the α+γ₂ matrix enhances the dealuminization of the alloy.