Structure and Corrosion Resistance of Cast ZnAl40Cu2 Alloy

Zn-Al-Cu alloys are used as an alternative material for bronze, cast iron and aluminum alloys in bearings and as construction material. Advantageous results brings of their application for bearings exposed to high loads. One of the factors determining the possible applications of Zn-Al-Cu alloys is their resistance to electrochemical corrosion. In literature can be found information on the corrosion resistance of Zn-Al-Cu alloys. There have been no comprehensive studies on the influence of casting conditions and modifications of chemical composition on the structure and corrosion resistance. The purpose of the experiments was to determine the structure and corrosion resistance of cast Zn-40%Al-2%Cu alloy. The scope of the experiments included X-ray phase analysis, potentiodynamic and potentiostatic tests, surface condition examinations and alloy structure characterization both before and after corrosion. The Zn40Al2Cu alloy is characterized by a dendritic structure, consisting of solid solutions of Al, Zn-Al and Zn and the CuZn5 phase. A corrosive environment affects the structure of the subsurface zone of the Zn40Al2Cu alloy to a depth of 60 to 130 μm, where a decrease of zinc content and an increase of aluminum content are observed.