The relationship between the wear behavior and microstructure features in end-chill cast Zn–27%Al alloy

An end-chill cast is conducted on Zn–27%Al alloy to produce a variety of microstructural features. The average cooling rate and the velocities of the liquid and solid fronts at several distances from the chill are measured. The structures of the alloy at 10 fixed distances are examined using an optical microscope and the corresponding hardness is measured. The wear behavior is investigated for three microstructures at distances of 1 mm, 10 mm and 90 mm from the chill. As a result of these investigations, the relationship between microstructural features and wear resistance of the alloy is determined. It is observed that the dendrite arm spacing (DAS), the percentage porosity and the interdendritic phase area increase with decreasing cooling rate, and consequently the wear resistance and the hardness value of the alloy decrease. The effect of each parameter is investigated independently, from which it is concluded that the decrease in dendrite arm spacing value is mainly responsible for the observed major improvement in wear behavior and hardness.