EXPERIMENTAL STUDY OF THE COLUMNAR-TO-EQUIAXED TRANSITION DURING DIRECTIONAL SOLIDIFICATION OF ZINC-ALUMINUM ALLOYS AND COMPOSITES

ALICIA ESTHER ARES; CARLOS ENRIQUE SCHVEZOV

World Journal of Engineering (WJOE)

Prof. Dr. Yuzhuang Sun (Editor-in-chief)

Lugar: Hebei University of Engineering, Guangming South Street 199, Handan, Hebei, China ,Zip Code: 056038.; Año: 2010 vol. 7 p. 13 - 29

1708-5284

The present study was undertaken to investigate the CET in Zn-Al (ZA) alloys (Zn-1wt%Al, Zn-2wt%Al, Zn-3wt%Al, Zn-4wt%Al, Zn-16wt%Al, Zn-27wt%Al, Zn-50wt%Al). The CET is observed and the observations related to the solidification thermal parameters: cooling rates, growth rates, thermal gradients, superheat, heat flow and recalescence determined from the temperature versus time curves.  Also, Zn-27wt%Al and Zn-50wt%Al composites with different compositions and with reinforcing particles of silicon carbide and alumina, were directionally solidified in approximately the same conditions and the CET was observed. The resulting structure in relation with the solidification parameters was analyzed. In the conditions of the experiments, the columnar length for ZA alloys + SiC(p) addition increases and in the case of ZA alloys + Al2O3(p) diminishes with increasing cooling rate. The temperature gradient and the velocity of the liquidus front reach minimum values at the CET for both, alloys and composites. The temperature gradients are between -0.25 K/mm and 0.16 K/mm; and the velocities are between 0.8 mm/s to 4.4 mm/s for both alloys and composites.