The effect of T4 heat treatment on the microstructure and corrosion behaviour of Zn27Al1.5Cu0.02Mg alloy

The effect of heat treatment on the microstructure and corrosion behaviour of Zn27Al1.5Cu0.02Mg alloy was examined. The alloy was prepared by melting and casting route and then thermally processed (T4 regime). Corrosion behaviour of the as-cast and heat treated alloy was studied in 3.5 wt.% NaCl solution using immersion method and electrochemical polarization measurements. The applied heat treatment affected the alloy microstructure and resulted in increased ductility and higher corrosion resistance of the heat treated alloy. Electrochemical measurements of the corrosion rate at the free corrosion potential are in agreement with the results obtained using the weight loss method.

Research highlights
► T4 heat treatment affected the microstructure and corrosion resistance of ZA27 alloy.
► T4 regime has a small beneficial effect on the corrosion resistance of ZA27 alloy.
► The alloy structure remained dendritic after T4 heat treatment.
► Corrosion process takes place through η phase and α + η phase mixture.