COLUMNAR TO EQUIAXED TRANSITION STUDIES IN ALUMINUM-SILICON AND ALUMINUM-SILICON-COPPER ALLOYS

ARES, ALICIA;; RUBENS CARAM; SCHVEZOV, CARLOS

Guaruja – SP - Brasil

Congreso; 3 International School on Crystal Growth and Advanced Materials. V Encontro da Sociedade Brasileira de Crescimento de Cristais; 2002

Universidade do Campina

Aluminum-silicon and aluminum-silicon-copper alloys were solidified directionally under conditions that produced the columnar to equiaxed transition. From the measured temperatures the following parameters were derived; the local temperature gradient, the cooling rate and the velocities of the liquid and solidus fronts. Comparing the location of the transition and the values of these parameters it was found that the temperature gradient reaches negative values of as low as –4.2 °C/cm, and velocities of the fronts of around 0.1 cm/s. Also, a supercooling between 0.33 °C to 1.86 °C was measured which was associated with the supercooling for the nucleation and growth of the equiaxed grains ahead of the columnar front. The results are presented and discussed in the frame of the results obtained for other alloys.