Titanium-containing article and method for making

Abstract

An article made of an alloy, and a method for making the article, are presented. The alloy is substantially free of martensite, and comprises the following composition: at least about 75 weight percent titanium; up to about 10 weight percent of a beta stabilizing component; from about 3 weight percent to about 15 weight percent of an alpha stabilizing component; and from about 0.05 weight percent to about 5 weight percent germanium. Another embodiment is a method for fabricating an article. The method comprises providing a billet made of an alloy as described above, and stabilizing the billet microstructure to form a stabilized billet; the method may further comprise superplastically processing the stabilized billet to form a processed item.

1 . An article comprising:
 an alloy substantially free of martensite, wherein the alloy comprises
 at least about 75 weight percent titanium; 
 up to about 10 weight percent of a beta stabilizing component; 
 from about 3 weight percent to about 15 weight percent of an alpha stabilizing component; and 
 from about 0.05 weight percent to about 5 weight percent germanium. 
   
     
     
         2 . The article of  claim 1 , wherein the alloy further comprises up to about 2 weight percent silicon. 
     
     
         3 . The article of  claim 1 , wherein the alloy further comprises up to about 1 weight percent boron. 
     
     
         4 . The article of  claim 1 , wherein the alloy further comprises silicon and boron. 
     
     
         5 . The article of  claim 4 , wherein the silicon is present at a level in the range from about 0.1 weight percent to about 1.5 weight percent and the boron is present at a level in the range from about 0.05 weight percent to about 0.4 weight percent. 
     
     
         6 . The article of  claim 1 , wherein the alloy further comprises phosphorous. 
     
     
         7 . The article of  claim 6 , wherein the phosphorous is present at a level of in the range from about 0.01 weight percent to about 2 weight percent. 
     
     
         8 . The article of  claim 1 , wherein the alloy further comprises phosphorous and silicon. 
     
     
         9 . The article of  claim 8 , wherein the phosphorous is present at a level in the range from about 0.01 weight percent to about 0.1 weight percent and the silicon is present at a level in the range from about 0.1 weight percent to about 1.5 weight percent. 
     
     
         10 . The article of  claim 1 , wherein the beta stabilizing component is present at a level in the range from about 3.5 weight percent to about 4.5 weight percent. 
     
     
         11 . The article of  claim 1 , wherein the beta stabilizing component comprises at least one material selected from the group consisting of refractory metals, platinum group metals, and transition metals. 
     
     
         12 . The article of  claim 1 , wherein the beta stabilizing component comprises at least one material selected from the group consisting of molybdenum, vanadium, tantalum, niobium, manganese, iron, chromium, cobalt, nickel, rhenium, palladium, tungsten, zirconium, and copper. 
     
     
         13 . The article of  claim 1 , wherein the beta stabilizing component comprises at least one material selected from the group consisting of vanadium, molybdenum, niobium, tantalum, and iron. 
     
     
         14 . The article of  claim 1 , wherein the alpha stabilizing component is present at a level in the range from about 5.5 weight percent to about 6.75 weight percent. 
     
     
         15 . The article of  claim 1 , wherein the alpha stabilizing component comprises at least one material selected from the group consisting of tin, aluminum, gallium, lanthanum, cerium, carbon, oxygen, and nitrogen. 
     
     
         16 . The article of  claim 1 , wherein the alpha stabilizing component comprises at least one material selected from the group consisting of aluminum and tin. 
     
     
         17 . The article of  claim 1 , wherein the alloy comprises
 about 6 weight percent aluminum;   about 4 weight percent vanadium; and   from about 0.05 weight percent to about 0.4 weight percent germanium.   
     
     
         18 . The article of  claim 1 , wherein the alloy comprises
 from about 5.5 weight percent to about 6.5 weight percent aluminum;   from about 1.8 weight percent to about 2.2 weight percent molybdenum;   from about 3.6 weight percent to about 4.4 weight percent zirconium;   from about 1.8 weight percent to about 2.2 weight percent tin;   wherein the germanium content is in the range from about 0.05 weight percent to about 1 weight percent.   
     
     
         19 . The article of  claim 1 , wherein the article comprises a component of a turbine assembly. 
     
     
         20 . The article of  claim 19 , wherein the component is an engine mount, a liner, a heat shield, a gear-box casing, a bladed disk, or a blade. 
     
     
         21 . The article of  claim 1 , wherein the article is a feedstock suitable for a fabrication process. 
     
     
         22 . A method for forming an article, the method comprising:
 providing a billet comprising an alloy substantially free of martensite, wherein the alloy comprises
 at least about 75 weight percent titanium, 
 up to about 10 weight percent of a beta stabilizing component, 
 from about 3 weight percent to about 15 weight percent of an alpha stabilizing component, and 
 from about 0.05 weight percent to about 5 weight percent germanium; and 
   
       stabilizing the billet microstructure, thereby forming a stabilized billet. 
     
     
         23 . The method of  claim 22 , further comprising superplastically processing the stabilized billet to form a processed item. 
     
     
         24 . The method of  claim 22 , wherein stabilizing the billet microstructure comprises heating the billet to a temperature and holding the billet at the temperature for a time sufficient to form a dispersion of precipitates in the billet. 
     
     
         25 . The method of  claim 24 , wherein the precipitates comprise an intermetallic compound of germanium. 
     
     
         26 . The method of  claim 25 , wherein the precipitates comprise titanium germanide. 
     
     
         27 . The method of  claim 24 , wherein the dispersion has a median precipitate size up to a grain size of the alloy. 
     
     
         28 . The method of  claim 24 , further comprising dissolving the precipitates after the superplastic processing step and heat treating the processed item. 
     
     
         29 . The method of  claim 22 , wherein stabilizing the billet microstructure comprises heating the billet to a temperature and holding the billet at the temperature for a time sufficient to dissolve at least some germanium-bearing precipitates. 
     
     
         30 . The method of  claim 22 , wherein providing the billet comprises providing a starting material and thermomechanically processing the starting material. 
     
     
         31 . The method of  claim 30 , wherein thermomechanically processing comprises processing via a Severe Plastic Deformation process. 
     
     
         32 . The method of  claim 31 , wherein the Severe Plastic Deformation process comprises Multi-Axis Forging. 
     
     
         33 . The method of  claim 22 , wherein the billet comprises a plurality of grains having a median grain size less than about 2 micrometers. 
     
     
         34 . The method of  claim 22 , wherein the billet comprises a plurality of grains having a median grain size less than about 1 micrometer. 
     
     
         35 . The method of  claim 22 , wherein the billet comprises a plurality of grains having a median grain size less than about 500 nanometers. 
     
     
         36 . The method of  claim 23 , further comprising heat treating the processed item to attain a desired grain size in the processed item.