Observations of Microhardness and Evolution of Constituents in Al?Zn and Zn?Al Specimens with Columnar-to-Equiaxed Grain Transition

R. S. ROSICKI; A. I. KOCIUBCZYK; G. R. KRAMER; ALICIA E. ARES

Light Metals 2018

Springer

Año: 2018; p. 1081 - 1088

Aluminum?zinc alloys are cheaper than aluminum?copperalloys, with equal mechanical properties, but lesscorrosion-resistance. On the other hand, zinc?aluminumalloys was technologically progressive for gravity casting,competing with bronze, cast iron and aluminum. Themechanical properties of these alloys are very importantfor different applications. In the present work, diluted Al?Zn (Al-2 wt%Zn and Al-4 wt%Zn) and Zn?Al (Zn-2 wt%Al and Zn-4 wt%Al) alloys were solidified directionallyupward, obtaining the columnar-to-equiaxed grain transition(CET) phenomenon. Through the measurement ofthe temperature profiles during solidification, the thermalparameters (cooling rates, temperature gradients andinterphase velocities, local solidification times) weredetermined. After that, the grain structure of the specimenswas observed from the chill to the top of thespecimens, and correlating with the evolution of principalconstituents of alloys (Al and Zn) along the specimens. Inaddition, microhardness measurements in different grainzones of the specimens, in the columnar (at the bottom),CET and in the equiaxed grain zone (at the top) weredone. The results obtained in different alloys and grainstructures were analyzed.