Experimental analysis of the solidification of Sn-3 wt.%Pb alloy under natural convection

A quasi-two-dimensional solidification benchmark experiment with controlled thermal boundary conditions is proposed. The experiment consists in solidifying a rectangular ingot of Sn-3 wt.%Pb alloy using two lateral heat exchangers to extract the heat flux from one or two sides of the sample. The temperature difference between the two sides of the heat exchangers may vary from 0 to 40 K and the cooling rate from 0.02 to 0.04 K/s. This slow-cooling condition has been used to promote segregation formation. An array of fifty thermocouples placed on the corresponding sample walls is used to determine the instantaneous temperature distribution. During the solidification process, the temperature field is recorded versus time and analyzed. This makes it possible to estimate the change in temperature due to natural convection, the velocity field and the solidification macrostructure and segregation behavior. After each experiment, the segregation patterns are obtained by X-ray analysis and confirmed by eutectic fraction measurements. The local solute distribution is determined by means of induction coupled plasma analysis. (C) 2011 Elsevier Ltd. All rights reserved.