Composite gas turbine blade and method of manufacturing same

Abstract

A composite gas turbine blade consists of an airfoil (1) in an oxide-dispersion-hardened nickel-based superalloy, in the condition of longitudinally directed coarse columnar crystals, and a shroud plate (6) or a shroud and a root (7), the latter items in a non-dispersion-hardened nickel-based superalloy (cast alloy). The gas turbine blade is manufactured by casting in and casting round, using the non-dispersion-hardened superalloy mentioned, the tip end (2) and root end (3)--provided with depressions (4) and/or protrusions (5)--of the airfoil (1), after preheating the latter to a temperature of between 50.degree. and 300.degree. C. below the solidus temperature of the lowest melting phase of the airfoil material. The casting temperature for this should be a maximum of 100.degree. C. above the liquidus temperature of the highest melting phase of this non-dispersion-hardened alloy. Any melting onto the airfoil (1) and any metallurgical connection is to be avoided. It is advantageous to provide a thermally insulating, mechanically damping intermediate layer (16) of an oxide of at least one of the elements Cr, Al, Si, Ti and Zr with a thickness of 5 to 200 .mu.m between the airfoil (1), on the one hand, and the shroud plate (6) and the root (7), on the other.