Espaçamentos dendríticos primários da liga Sn-5%Pb solidificada direcionalmente em um sistema horizontal

Abstract

In order to investigate the effect of thermal parameters on the primary dendritic spacings of Sn - 5%Pb alloy, horizontal directional solidification experiments have been carried out under unsteady state heat flow conditions. Thermocouples have been connected with the metal, and the time - temperature data have been recorded automatically. The results include metal/mold heat transfer coefficient determined from comparisons between the experimental thermal profiles and simulations provided by a numerical model. A combined theoretical and experimental approach is developed to determine the solidification thermal parameters: tip growth rates, and cooling rates. The experimental and calculated values have shown a good agreement. A comparative study between experimental data of this work and those from the literature proposed to predict the primary spacings during upward and downward vertical unsteady-state directional solidification of Sn - Pb alloys is presented. The observation of the microstructures has indicated that the primary dendritic spacings have been affected by the direction of growth, increasing in conditions of horizontal solidification when compared with those obtained during vertical solidification.