Convective Transport Phenomena and Macrosegregation During Solidification of a Binary Metal Alloy: II—Experiments and Comparisons With Numerical Predictions

Experiments involving the solidification of a Pb-19 percent Sn alloy in an axisymmetric, annular mold of stainless steel are performed, and results are compared with numerical predictions. Agreement between measured and predicted cooling curves is reasonable, although undercooling and recalescence, which occur in the experiments, are not predicted by the model. Measured temperatures also indicate that dendrite fragments are transported throughout the mold cavity during early stages of solidification, and convection patterns similar to those predicted by numerical simulation can be inferred from the measurements. While there is general agreement between measured and predicted trends for macrosegregation, the numerical simulation, which assumes axial symmetry, cannot predict the inherently three-dimensional nature of solute redistribution. Conclusions drawn from temperature and composition measurements are supported by metallographic examinations of experimental ingot specimens.