Corrosion and Wear Resistance of Hypoeutectic Zn-Al Alloys as a Function of Structural Features

ARES, A.E.; GASSA, L.M.; SCHVEZOV, C. E.; MARIO ROBERTO ROSENBERGER

MATERIALS CHEMISTRY AND PHYSICS

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2012 vol. 136 p. 394 - 414

0254-0584

Abstract: The aim of the present research was to investigate the role of the type of grainmacrostructure (columnar, columnar-to-equiaxed transition, CET, and equiaxed) and microstructure(secondary dendritic arm spacing) in the wear and electrochemical behavior of hypereutectic Zn-Alalloys (Zn-1wt%Al, Zn-2wt%Al, Zn-3wt%Al and Zn-4wt%Al) directionally solidified in a verticalupward directional solidification device. The results obtained in this alloy system indicate that thecorrosion resistance increases with the concentration of aluminum, but even at the highestconcentrations depends on the structure. The microstructure (smaller grain size and secondarydendritic arm spacing) for the columnar structure increases the susceptibility to corrosion. For thesame wear conditions, the wear rate of the equiaxed region is lower than the columnar and transitionregions. Independently of the type of structure the wear resistance increases with the aluminumconcentration. For each alloy concentration, the wear resistance increases from the columnar to theequiaxed structure. A clear inverse relation is observed between the wear resistance and thesecondary dendritic arm spacing, which may explain the increase in wear resistance in the equiaxedregion. At low spacings, the wear rate converges to a single value