Niobium-based alloys with improved structural properties for high temperature structural applications

Abstract

A niobium-based refractory alloy. The inclusion of measurable, controlled amounts of interstitial nitrogen improves one or more structural properties of the alloy. Components made with the alloy have higher strengths, especially at elevated temperatures, while ductility and oxidation resistance are not adversely affected. In particular, components for use in ground-based and air-based gas turbine engine hot sections can utilize the alloy in order to realize improvements in one or more of service life, operational efficiency and design simplification.

What is claimed is: 
     
         1 . A niobium-molybdenum-titanium alloy comprising, by weight:
 about 10 percent to about 34 percent molybdenum;   about 2 percent to about 20 percent titanium;   up to about 30 percent hafnium;   up to about 10 percent aluminum;   up to about 20 percent chromium;   up to about 15 percent tantalum;   up to about 15 percent tungsten;   up to about 10 percent zirconium;   about 0.1 percent to about 3.0 percent nitrogen;   at least one elemental alloy addition selected from the group consisting of carbon, oxygen and mixtures thereof; and   a balance of niobium.   
     
     
         2 . The alloy of  claim 1 , wherein the molybdenum comprises between about 14 percent and about 34 percent by weight. 
     
     
         3 . The alloy of  claim 1 , wherein the titanium comprises between about 2.7 percent and about 14.4 percent by weight. 
     
     
         4 . The alloy of  claim 1 , wherein the hafnium comprises between about 0 percent and about 29 percent by weight. 
     
     
         5 . The alloy of  claim 1 , wherein the aluminum comprises between about 0 percent and about 6.8 percent by weight. 
     
     
         6 . The alloy of  claim 1 , wherein the chromium comprises between about 0 percent and about 18.3 percent by weight. 
     
     
         7 . The alloy of  claim 1 , wherein the tantalum comprises between about 0 percent and about 0.1 percent by weight. 
     
     
         8 . The alloy of  claim 1 , wherein the tungsten comprises between about 0 percent and about 6.1 percent by weight. 
     
     
         9 . The alloy of  claim 1 , wherein the zirconium comprises between about 0 percent and about 5 percent by weight. 
     
     
         10 . The alloy of  claim 1 , wherein the nitrogen comprises between about 0.3 percent and about 1.4 percent by weight. 
     
     
         11 . The alloy of  claim 10 , wherein the nitrogen comprises between about 0.5 percent and about 1.2 percent by weight. 
     
     
         12 . The alloy of  claim 11  wherein the nitrogen comprises between about 0.6 percent and about 1.3 percent by weight. 
     
     
         13 . The alloy of  claim 12 , wherein the nitrogen comprises between about 0.7 percent and about 1.2 percent by weight. 
     
     
         14 . The alloy of  claim 13 , wherein the nitrogen comprises between about 0.8 percent and about 1.1 percent by weight. 
     
     
         15 . The alloy of  claim 1 , wherein at least a portion of the titanium is present as a titanium nitride-based secondary phase precipitate. 
     
     
         16 . The alloy of  claim 1 , wherein at least a portion of the hafnium is present as a hafnium nitride-based secondary phase precipitate. 
     
     
         17 . The alloy of  claim 1 , wherein at least a portion of the titanium is present as a titanium nitride-based secondary phase precipitate and at least a portion of the hafnium is present as a hafnium nitride-based secondary phase precipitate. 
     
     
         18 . A component with enhanced structural properties, the component made from a niobium-molybdenum-titanium alloy comprising, by weight:
 about 10 percent to about 34 percent molybdenum;   about 2 percent to about 20 percent titanium;   up to about 30 percent hafnium;   up to about 10 percent aluminum;   up to about 20 percent chromium;   up to about 15 percent tantalum;   up to about 15 percent tungsten;   up to about 10 percent zirconium;   about 0.1 percent to about 3.0 percent nitrogen;   at least one elemental alloy addition selected from the group consisting of carbon, oxygen and mixtures thereof; and   a balance of niobium such that the structural properties that are selected from a group consisting of yield strength, true peak stress and true fracture stress, exhibit increases their respective figures of merit over a niobium-molybdenum-titanium alloy that comprises nitrogen in an amount greater or less than the percent recited herein.   
     
     
         19 . A gas turbine engine component comprising:
 a substrate comprising a niobium-molybdenum-titanium alloy comprising, by weight:
 about 10 percent to about 34 percent molybdenum; 
 about 2 percent to about 20 percent titanium; 
 up to about 30 percent hafnium; 
 up to about 10 percent aluminum; 
 up to about 20 percent chromium; 
 up to about 15 percent tantalum; 
 up to about 15 percent tungsten; 
 up to about 10 percent zirconium; 
 about 0.1 percent to about 3.0 percent nitrogen; 
 at least one elemental alloy addition selected from the group consisting of carbon, oxygen and mixtures thereof; and 
 a balance of niobium; and 
   a coating disposed over at least a portion of the substrate.   
     
     
         20 . The gas turbine engine component of  claim 19 , wherein the component comprises at least one of a turbine blade, a turbine vane and a diffuser.