ABSTRACT
Castings are produced with a variety of dimensions, from of a few millimeters up to tens of meters in length. It is natural, therefore, to assume that the important dimensions to use in describing castings are of that magnitude. However, as the microstructure of the casting (the structure which can be seen using an optical microscope) determines the properties of the casting, it, too, is important. In addition, because solidification is the process of moving individual atoms from the liquid to a more stable position in the alloy lattice, the distances which atoms must move during solidification are also important. For these reasons, the effect of solidification on the casting must be analyzed at three different length scales (Fig. l) [l]:
l. The macroscale (macrostructure): This scale is of the order of centimeters to meters. Elements of the macroscale include shrinkage cavity, macrosegregation, cracks, surface quality, and casting dimensions. Casting properties, and their acceptance by the customer, can sometimes be dramatically influenced by these macrostructure features.
