A method of directionally solidifying a molten alloy is presented. The molten alloy is disposed in a shell mold that has a thermal conductivity value greater than about 2 W/m-K. During the direction solidification, heat is transferred from the shell mold to a cooling region with a heat extraction rate greater than about 120 W/m.sup.2.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
 This invention was made with Government support under contract number DE-EE0005573, awarded by the U.S. Department of Energy. The Government has certain rights in the invention.