Determination of the Latent Heat of Fusion and the Solidification Path of a Hypoeutectic Al Based Alloy Using the Energy Balance Method

In this work the method of computer-aided cooling curve analysis named Metal / Mold Energy Balance (MEB) is applied to a hypoeutectic Al-7.5% Si alloy in order to determine the latent heat of fusion and the solidification path of this alloy and to compare its predictions with respect to the values of latent heat reported in the literature. For this purpose, the liquid alloy was prepared in a silicon carbide crucible inside an electric furnace, using burdens of aluminum and silicon of commercial purity. The chemical composition of the alloy was controlled using a spark emission spectrometer. Cylindrical stainless steel molds were used to contain the liquid samples. Once the liquid alloy and the mold were prepared, the liquid sample was transferred to the mold and the thermocouples inserted in the sample and in the mold to obtain their cooling curves during the cooling and solidification of the sample. The cooling curves were numerically processed by the MEB method, based on energy balances applied to the composite mold /liquid alloy sample system. The cooling curves obtained for the sample were also processed numerically using two of the most used Newtonian cooling curve analysis methods in order to compare their performances in the determination of latent heat of solidification and the evolution of the solid fraction. The results obtained in this work suggest that the MEB method presents a better performance in the determination of the latent heat of fusion and predicts solid fraction evolutions similar to those predicted by the conventional Newtonian methods.