Observations of Microhardness and Evolution of Constituents in AlZn and ZnAl Specimens with Columnar to Equiaxed Grain Transition

GUSTAVO R. KRAMER; ALEX I. KOCIUBCZYK; ALICIA E. ARES; ROBERTO S. ROZICKI

Phoenix; United States

Otro; Light Metals 2018; 2018

The Minerals, Metals & Materials Society (TMS)

Aluminum zinc alloys are cheaper than aluminum copper alloys, with equal mechanical properties, but less corrosion resistance. On the other hand, zinc aluminum alloys was technologically progressive for gravity casting,competing with bronze, cast iron and aluminum. The mechanical properties of these alloys are very important for different applications. In the present work, diluted AlZn (Al2wt%Zn and Al4wt%Zn) and ZnAl (Zn2wt%Al and Zn4wt%Al) alloys were solidified directionally upward, obtaining the columnar-to-equiaxed grain transition (CET) phenomenon. Through the measurement of the temperature profiles during solidification, the thermal parameters (cooling rates, temperature gradients and interphase velocities, local solidification times) weredetermined. After that, the grain structure of the specimens was observed from the chill to the top of the specimens, and correlating with the evolution of principal constituents of alloys (Al and Zn) along the specimens. Inaddition, microhardness measurements in different grain zones of the specimens, in the columnar (at the bottom), CET and in the equiaxed grain zone (at the top) were done. The results obtained in different alloys and grain structures were analyzed.