Beta titanium compositions and methods of manufacture thereof

Abstract

A composition comprises about 8 to about 10 wt % molybdenum, about 2.8 to about 6 wt % aluminum, up to about 2 wt % vanadium, up to about 4 wt % niobium, with the balance being titanium, wherein the weight percents are based on the total weight of the alloy composition. A method for making an article comprises cold-working a shape from a composition comprising about 8 to about 10 wt % molybdenum, about 2.8 to about 6 wt % aluminum, up to about 2 wt % vanadium, up to about 4 wt % niobium, with the balance being titanium, wherein the weight percents are based on the total weight of the alloy composition; solution heat treating the shape; and cooling the shape.

What is claimed is:  
     
         1 . An alloy composition comprising: 
 titanium; and    a molybdenum equivalent weight of about 7 to about 11 wt %, wherein the weight percents are based upon the total weight of the alloy composition, wherein the alloy composition is superelastic and/or pseudoelastic.    
     
     
         2 . The composition of  claim 1 , wherein the composition is cold worked and/or solution treated; and wherein the solution treating can be conducted at a temperature above and/or below the β transus temperature.  
     
     
         3 . The composition of  claim 1 , wherein the molybdenum equivalent weight is determined by the equation (1)  
       MO eq. =1.00Mo+0.28Nb+0.22Ta+0.67V+1.43Co+1.60Cr+0.77Cu+2.90Fe+1.54Mn+1.11Ni+0.44W−1.00Al  (1) or the equation (2) MO eq. =1.00Mo+0.28Nb+0.22Ta+0.67V+1.43Co+1.60Cr+0.77Cu+2.90Fe+1.54Mn+1.11 Ni+0.44W+0.25(Sn+Zr+Hf)−1.00Al  (2)  
       wherein Mo is molybdenum, Nb is niobium, Ta is tantalum, V is vanadium, Co is cobalt, Cr is chromium, Cu is copper, Fe is iron, Mn is manganese, Ni is nickel, W is tungsten, Al is aluminum, Sn is tin, Zr is zirconium and Hf is hafnium; wherein aluminum can be substituted by gallium, carbon, germanium and/or boron; and wherein the respective chemical symbols represent the amounts of the respective elements in weight percent based on the total weight of the alloy composition.  
     
     
         4 . The composition of  claim 1 , comprising: 
 about 8 to about 10 wt % molybdenum,    about 2.8 to about 6 wt % aluminum,    up to about 2 wt % vanadium,    up to about 4 wt % niobium, with the balance being titanium, wherein the weight percents are based on the total weight of the alloy composition, and wherein the composition is cold worked.    
     
     
         5 . The composition of  claim 4 , further comprising solution treating the composition at a temperature of greater than or equal to the β transus temperature for a time period of greater than or equal to about 30 seconds.  
     
     
         6 . The composition of  claim 5 , wherein the temperature is about 850 to about 1000° C.  
     
     
         7 . The composition of  claim 4 , further comprising solution treating the composition at a temperature of less than or equal to the β transus temperature for a time period of greater than or equal to about 1 minute.  
     
     
         8 . The composition of  claim 7 , wherein the temperature is about 750 to about 850° C.  
     
     
         9 . The composition of  claim 1 , wherein the composition has a β phase and/or an α and a β phase.  
     
     
         10 . The composition of  claim 1 , wherein the composition has an elastic recovery of greater than or equal to about 75% of the applied change in length when the applied change in length is 2% of the original length.  
     
     
         11 . The composition of  claim 1 , wherein the composition has an elastic recovery of greater than or equal to about 85% of the applied change in length when the applied change in length is 2% of the original length.  
     
     
         12 . The composition of  claim 1 , wherein the composition has an elastic recovery of greater than or equal to about 50% of the applied change in length when the applied change in length is 4% of the original length.  
     
     
         13 . The composition of  claim 1 , wherein the composition has an elastic recovery of greater than or equal to about 75% of the applied change in length when the applied change in length is 4% of the original length.  
     
     
         14 . The composition of  claim 1 , wherein the composition after cold working has a reduction in the elastic modulus of greater than or equal to about 10% when compared with the elastic modulus of an equivalent heat treated composition.  
     
     
         15 . The composition of  claim 1 , wherein the composition after cold working has a reduction in the elastic modulus of greater than or equal to about 20% when compared with the elastic modulus of an equivalent heat treated composition.  
     
     
         16 . The composition of  claim 1 , wherein the composition after cold working has a reduction in the elastic modulus of greater than or equal to about 25% when compared with the elastic modulus of an equivalent heat treated composition.  
     
     
         17 . The composition of  claim 4 , wherein the composition, after cold working and/or solution treating, has an elastic recovery of greater than or equal to about 75% of the applied change in length when the applied change in length is 2% of the original length.  
     
     
         18 . The composition of  claim 4 , wherein the composition, after cold working and/or solution treating, has an elastic recovery of greater than or equal to about 85% of the applied change in length when the applied change in length is 2% of the original length.  
     
     
         19 . The composition of  claim 4 , wherein the composition, after cold working and/or solution treating, has an elastic recovery of greater than or equal to about 50% of the applied change in length when the applied change in length is 4% of the original length.  
     
     
         20 . The composition of  claim 4 , wherein the composition, after cold working and/or solution treating, has an elastic recovery of greater than or equal to about 75% of the applied change in length when the applied change in length is 4% of the original length.  
     
     
         21 . The composition of  claim 4 , wherein the composition, after cold working, has a reduction in the elastic modulus of greater than or equal to about 10% when compared with the elastic modulus of an equivalent heat treated composition.  
     
     
         22 . The composition of  claim 4 , wherein the composition, after cold working, has a reduction in the elastic modulus of greater than or equal to about 20% when compared with the elastic modulus of an equivalent heat treated composition.  
     
     
         23 . The composition of  claim 4 , wherein the composition, after cold working, has a reduction in the elastic modulus of greater than or equal to about 25% when compared with the elastic modulus of an equivalent heat treated composition.  
     
     
         24 . An article manufactured from the composition of  claim 1 .  
     
     
         25 . An article manufactured from the composition of  claim 4 .  
     
     
         26 . A method for making an article comprising: 
 working a shape, wherein the shape has a composition comprising titanium; and a molybdenum equivalent weight of about 7 to about 11 wt %, wherein the weight percents are based upon the total weight of the alloy composition; and wherein the molybdenum equivalent weights are determined by the equation (1)    MO eq. =1.00Mo+0.28Nb+0.22Ta+0.67V+1.43Co+1.60Cr+0.77Cu+2.90Fe+1.54Mn+1.11Ni+0.44W−1.00Al  (1) or the equation (2) MO eq. =1.00Mo+0.28Nb+0.22Ta+0.67V+1.43Co+1.60Cr+0.77Cu+2.90Fe+1.54Mn+1.11 Ni+0.44W+0.25(Sn+Zr+Hf)−1.00Al  (2)    wherein Mo is molybdenum, Nb is niobium, Ta is tantalum, V is vanadium, Co is cobalt, Cr is chromium, Cu is copper, Fe is iron, Mn is manganese, Ni is nickel, W is tungsten, Al is aluminum, Sn is tin, Zr is zirconium and Hf is hafnium; wherein the aluminum can be substituted by boron, carbon, gallium and/or germanium and wherein the respective chemical symbols represent the amounts of the respective elements in weight percent based on the total weight of the alloy composition;    solution treating the shape; and    cooling the shape.    
     
     
         27 . The method of  claim 26 , wherein the working is accomplished through cold working or hot working.  
     
     
         28 . The method of  claim 26 , wherein the solution treating is conducted at a temperature below the β transus temperature for the composition.  
     
     
         29 . The method of  claim 26 , wherein the solution treating is conducted at a temperature above the β transus temperature for the composition.  
     
     
         30 . The method of  claim 26 , wherein the cooling is conducted in air and/or an inert gas.  
     
     
         31 . The method of  claim 26 , wherein the shape is further heat aged at a temperature of about 350 to about 550° C.  
     
     
         32 . The method of  claim 31 , wherein the heat ageing is conducted for a time period of 10 seconds to about 8 hours.  
     
     
         33 . The method of  claim 26 , further comprising cold working the shape.  
     
     
         34 . A method for making an article comprising: 
 cold working a shape from a composition comprising about 8 to about 10 wt % molybdenum, about 2.8 to about 6 wt % aluminum, up to about 2 wt % vanadium, up to about 4 wt % niobium, with the balance being titanium, wherein the weight percents are based on the total weight of the alloy composition;    solution treating the shape; and    cooling the shape.    
     
     
         35 . The method of  claim 34 , wherein the solution treating is conducted at a temperature below the isomorphic temperature for the composition.  
     
     
         36 . The method of  claim 34 , wherein the solution treating is conducted at a temperature above the isomorphic temperature for the composition.  
     
     
         37 . The method of  claim 34 , wherein the cooling is conducted in air.  
     
     
         38 . The method of  claim 34 , wherein the shape is further heat aged at a temperature of about 350 to about 550° C.  
     
     
         39 . The method of  claim 38 , wherein the heat ageing is conducted for a time period of 10 seconds to about 8 hours.  
     
     
         40 . The method of  claim 34 , further comprising cold working the shape.  
     
     
         41 . A method comprising: 
 cold working a wire having a composition comprising titanium; and a molybdenum equivalent weight of about 7 to about 11 wt %, wherein the weight percents are based upon the total weight of the alloy composition; and wherein the molybdenum equivalent weights are determined by the equation (1)    MO eq. =1.00Mo+0.28Nb+0.22Ta+0.67V+1.43Co+1.60Cr+0.77Cu+2.90Fe+1.54Mn+1.11 Ni+0.44W−1.00Al  (1) or the equation (2) MO eq. =1.00Mo+0.28Nb+0.22Ta+0.67V+1.43Co+1.60Cr+0.77Cu+2.90Fe+1.54Mn+1.11 Ni+0.44W+0.25(Sn+Zr+Hf)−1.00Al  (2)    wherein Mo is molybdenum, Nb is niobium, Ta is tantalum, V is vanadium, Co is cobalt, Cr is chromium, Cu is copper, Fe is iron, Mn is manganese, Ni is nickel, W is tungsten, Al is aluminum, S is tin, Zr is zirconium and Hf is hafnium; and wherein the respective chemical symbols represent the amounts of the respective elements in weight percent based on the total weight of the alloy composition;    solution treating the wire; and    heat treating the wire.    
     
     
         42 . The method of  claim 41 , wherein the composition comprises about 8 to about 10 wt % molybdenum, about 2.8 to about 6 wt % aluminum, up to about 2 wt % vanadium, up to about 4 wt % niobium, with the balance being titanium, wherein the weight percents are based on the total weight of the alloy composition.  
     
     
         43 . The method of  claim 41 , wherein the cold working results in a reduction in cross-sectional area of about 5 to about 85%.  
     
     
         44 . The method of  claim 41 , wherein the wire diameter is about 0.1 to about 10 millimeters.  
     
     
         45 . The method of  claim 41 , wherein the heat treating is conducted at a temperature of about 500° C. to about 900° C.  
     
     
         46 . The method of  claim 41 , wherein the wire is solution treated at a temperature of about 800 to about 1000° C.  
     
     
         47 . The method of  claim 41 , wherein the article has a β phase or an α phase and a β phase.  
     
     
         48 . The method of  claim 41 , wherein the article has an elastic recovery of greater than or equal to about 75% of the applied change in length when the applied change in length is 2% of the original length.  
     
     
         49 . The method of  claim 41 , wherein the article has an elastic recovery of greater than or equal to about 50% of the applied change in length when the applied change in length is 4% of the original length.