Experimental Study of the Columnar-to-Equiaxed Transition during Directional Solidification of Zinc-Aluminum Alloys and Composites

A.E. ARES ; CARLOS ENRIQUE SCHVEZOV

World Journal of Engineering (WJOE

University of New Orleans

Lugar: New Orleans; 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 solidificationthermal parameters: cooling rates, growth rates, thermal gradients, superheat, heat flowand recalescence determined from the temperature versus time curves. Also,Zn-27wt%Al and Zn-50wt%Al composites with different compositions and withreinforcing particles of silicon carbide and alumina, were directionally solidified inapproximately the same conditions and the CET was observed. The resulting structure inrelation with the solidification parameters was analyzed. In the conditions of theexperiments, the columnar length for ZA alloys + SiC(p) addition increases and in thecase of ZA alloys + Al2O3(p) diminishes with increasing cooling rate. The temperaturegradient 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 0.16K/mm; and the velocities are between 0.8 mm/s to 4.4 mm/s for both alloys andcomposites