COLUMNAR-TO-EQUIAXED TRANSITION STUDIES IN Al-2wt%Cu, Al-4wt%Cu, Al-10wt%Cu, Al-20wt%Cu AND Al-33.2wt%Cu ALLOYS

ARES, ALICIA;; CARAM, RUBENS;; RIOS, CARLOS; SCHVEZOV, CARLOS

Solidification of Aluminum Alloys

G.Chu, D.A. Granger and Q. Han, editores. A publication of the Minerals, Metals, & Materials Society.

Lugar: Charlotte, North Carolina. USA.; Año: 2004; p. 751 - 766

The columnar to equiaxed transition (CET) was studied in Al-2wt%Cu, Al-4wt%Cu, Al-10wt%Cu, Al-20wt%Cu and Al-33.2wt%Cu alloys, which were solidified directionally from a chill face. The main parameters analyzed include melt superheat, cooling rate of the melt, position of the solidification fronts for the solidus and the liquidus temperature, local solidification time, velocity of both solidification fronts, length of the mushy zone, cooling rate of the solid and temperature gradients. The transition does not occur in abrupt form in the samples and 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. The size of the equiaxed grains increase with distance from the transition, an observation that was independent of alloy composition. In all uses the results obtained in the present investigation are compared with previous results published in the literature.