Microstructure and corrosion resistance of simultaneous Al–Fe coating on copper by pack cementation

Simultaneous Al–Fe coatings on copper were prepared by pack cementation to investigate the microstructure and corrosion resistance. The cross-section of prepared specimen was analyzed by scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Then the cross-section of specimen corroded by solution of ferric chloride in ethanol was evaluated using SEM and X-ray diffraction (XRD). The coating consists of an intermetallic layer and an interdiffusion layer, and the thickness of coating layer increases parabolically with holding temperatures from 730 °C to 900 °C. The aluminum content in the coating varies between 7.65 and 4.0% from the surface to the inside layer while the iron content varies between 2 and 0.5%. The coating layer is composed of а-Cu/Al solid solution with a small amount of iron. Alumina formed on the surface of the coating layer during corrosion provides very good protection for the coating layer in the corrosive atmosphere and enhances the corrosion resistance of the coating.