Abstract: This is a process of fabricating turbine blades for combustion turbines. It is an improvement to the type of process where a mold containing molten metal is cooled in a controlled fashion such that solidification occurs slow enough to allow single crystal growth beginning at the airfoil end. In the improved process solidification is monitored and magnetic mixing of the remaining molten metal is started at approximately the beginning of solidification of said root section and at approximately the same time the rate of cooling of said blade is increased to a rate faster than at which single crystal growth occurs. Grain boundary strengthener (preferably carbon) can be added at approximately the same time mixing is begun. A blade is produced with a single crystal airfoil section and a fine grained root section and without a substantially inhomogeneous portion at the interface between the airfoil and root sections.

Abstract: A cobalt-base alloy particularly for the cast parts of gas engines which operate at high temperatures, such as stationary blades of turbines, vanes of large cross-sectional and the like. The alloy has the minimum practicable of zirconium so that detrimental inter-dendritic carbide oxidation is suppressed. The surface of castings of this alloy readily lend themselves to coating with oxidation and sulfidation resistant coatings. In addition, the carbide oxidation attack of the crucible in which the alloy is melted or molded is minimized so that the economy of producing castings is materially improved. Also, improved is the internal structure of the investment castings produced in normal shop practice; i.e., equiaxed grain size, as distinct from columnar grain size, is produced and this results in an increase in the integrity of cast properties in large castings.