Fabricated turbine airfoil

Abstract

The invention provides an apparatus and method for combining materials having different thermal and mechanical properties into an article, such as a gas turbine bucket, which includes a first section, a second section, and a third section; wherein the first section provides structural support for the remaining sections, the second section is integrally joined with the first section, and the third section connects the first and second sections.

What is claimed is: 
     
         1 . A fabricated turbine airfoil comprising a first section, a second section, and a third section; wherein the first section provides structural support for the remaining sections, the second section is integrally joined with the first section, and the third section connects the first and second sections. 
     
     
         2 . The airfoil of  claim 1 , wherein the first section comprises an aerodynamically shaped load bearing member, a first end, and a second end. 
     
     
         3 . The airfoil of  claim 2 , wherein the first end is integral with or attached to a rotor. 
     
     
         4 . The airfoil of  claim 2 , wherein the second end is exposed to elevated temperatures, high velocity gases, or an otherwise degrading environment. 
     
     
         5 . The airfoil of  claim 4 , wherein the second section protects the second end from the degrading environment. 
     
     
         6 . The airfoil of  claim 1 , wherein the second section is comprised of a different material than the first and third sections. 
     
     
         7 . The airfoil of  claim 1 , wherein the third section comprises a sleeve. 
     
     
         8 . The airfoil of  claim 1 , wherein the second section is bonded to the third section. 
     
     
         9 . The airfoil of  claim 8 , wherein the bond between the second section and the third section is formed using a braze alloy. 
     
     
         10 . The airfoil of  claim 2 , wherein the third section is attached to the second end of the first section. 
     
     
         11 . A fabricated turbine bucket comprising a first section, a second section, and a third section; wherein the first section provides structural support for the remaining sections and comprises a load bearing member, a first end, and a second end exposed to elevated temperatures, high velocity gases, or an otherwise degrading environment; the second section protects the second end from the degrading environment and is integrally joined with the first section, and the third section connects the first and second sections. 
     
     
         12 . The bucket of  claim 11 , wherein the first section comprises an airfoil. 
     
     
         13 . The bucket of  claim 11 , wherein the first end is integral with or attached to a rotor. 
     
     
         14 . The bucket of  claim 11 , wherein the second section is comprised of a different material than the first and third sections. 
     
     
         15 . The bucket of  claim 11 , wherein the third section comprises a sleeve. 
     
     
         16 . The bucket of  claim 11 , wherein the second section is bonded to the third section. 
     
     
         17 . The bucket of  claim 16 , wherein the bond between the second section and the third section is formed using a braze alloy. 
     
     
         18 . The bucket of  claim 11 , wherein the third section is attached to the second end of the first section using any suitable method resulting in a joint having high mechanical integrity.