Columnar to Equiaxed Transition in Zn27wt.Al Alloys: A Comparation between Vertical and Horizontal Directional Solidifications

ALICIA ESTHER ARES; CARLOS ENRIQUE SCHVEZOV

Orlando

Simposio; Advances in the Science and Engineering of Casting Solidification: An MPMD Symposium Honoring Doru Michael Stefanescu; 2015

TMS

The columnar to equiaxed transition (CET) was studied in ZnAl alloys, which were directionally solidified from a chill face in both vertical and horizontal arrangement of experimental device. The main parameters analyzed include melt superheat, cooling rate of the melt, position of the solidification fronts for solidus and liquidus temperatures, local solidification time, velocity of solidification fronts, length of the mushy zone, cooling rate of the solid and temperature gradients. The CET does not occur in abrupt form in the samples and the phenomenon is present when the gradient in the liquid ahead of the columnar dendrites reaches critical and minimum values, being negative in most of the cases. In addition, there is an increase in the velocity of the liquidus front faster than the solidus front, which increases the size of the mushy zone. Keywords: CET, AlZn alloys, vertical solidification, horizontal solidification, thermal parameters.