Method of making an article of a titanium alloy by plastically deforming at room temperature and/or polishing

Abstract

A method of making an article of a titanium alloy is disclosed, which includes i) quenching a work piece, which is made of a titanium alloy composition containing a) about 0.01-5 wt % Bi based on the weight of the composition; b) at least one alloy element selected from the group consisting of Mo, Nb, Ta, Zr and Hf; and c) the balance Ti, having a temperature higher than a beta transition temperature of the titanium alloy composition to a temperature lower than 500° C. at a cooling rate greater than 10° C./second between the beta transition temperature and 500° C., so that the quenched work piece contains beta phase as a major phase; and ii) plastically deforming the quenched work piece or polishing the quenched work piece so that a surface of the polished work piece has an average surface roughness less than about 0.1 μm.

1 . A method of making an article of a titanium alloy comprising 
 i) quenching a work piece, which is made of a titanium alloy composition comprising a) about 0.01-5 wt % Bi based on the weight of the composition; b) at least one alloy element selected from the group consisting of Mo, Nb, Ta, Zr and Hf; and c) the balance Ti, having a temperature higher than a beta transition temperature of said titanium alloy composition to a temperature lower than 500° C. at an average cooling rate greater than 10° C./second between the beta transition temperature and 500° C., so that the quenched work piece contains β phase with a body-centered cubic crystal structure as a major phase; and ii) plastically deforming the quenched work piece.    
   
   
       2 . The method of  claim 1 , wherein said cooling rate is greater than 25° C./second.  
   
   
       3 . The method of  claim 1 , wherein the work piece to be quenched in step i) has a thickness less than 1.0 cm.  
   
   
       4 . The method of  claim 1 , wherein the work piece to be quenched in step i) has a thickness less than 0.5 cm.  
   
   
       5 . The method of  claim 3 , wherein said average cooling rate is greater than 25° C./second.  
   
   
       6 . The method of  claim 1  further comprising iii) heating the deformed work piece to a temperature higher than 500° C.; and iv) cooling the heated deformed work piece.  
   
   
       7 . The method of  claim 1 , wherein the work piece has a temperature of 800-1200° C. before said quenching in step i).  
   
   
       8 . The method of  claim 1 , wherein said plastically deforming in step ii) is carried out at room temperature.  
   
   
       9 . The method of  claim 1 , wherein said titanium alloy composition comprises 0. 1-3 wt % Bi.  
   
   
       10 . The method of  claim 9 , wherein said titanium alloy composition further comprises at least one eutectoid beta stabilizing element selected from the group consisting of Fe, Cr, Mn, Co, Ni, Cu, Ag, Au, Pd, Si and Sn.  
   
   
       11 . The method of  claim 9 , wherein said titanium alloy composition consists essentially of 0.1-3 wt % Bi, 10-50 wt % of at least one alloy element selected from the group consisting of Mo, Nb, Ta, Zr and Hf, based on the weight of the composition, and the balance Ti.  
   
   
       12 . The method of  claim 11 , wherein said titanium alloy composition consists essentially of 0.5-1.5 wt % Bi, 10-20 wt % of Mo, based on the weight of the composition, and the balance Ti.  
   
   
       13 . The method of  claim 11 , wherein said titanium alloy composition consists essentially of about 1 wt % Bi, about 15 wt % of Mo, based on the weight of the composition, and the balance Ti.  
   
   
       14 . The method of  claim 6  further comprising v) polishing the cooled work piece so that a surface of the polished work piece has an average surface roughness less than about 0.1 μm.  
   
   
       15 . The method of  claim 1  further comprising polishing the plastically deformed work piece so that a surface of the polished work piece has an average surface roughness less than about 0.1 μm.  
   
   
       16 . The method of  claim 1 , wherein said article is a dental casting.  
   
   
       17 . The method of  claim 1 , wherein said article is a medical implant.  
   
   
       18 . A method of making an article of a titanium alloy comprising 
 I) quenching a work piece, which is made of a titanium alloy composition comprising a) about 0.01-5 wt % Bi based on the weight of the composition; b) at least one alloy element selected from the group consisting of Mo, Nb, Ta, Zr and Hf; and c) the balance Ti, having a temperature higher than a beta transition temperature of said titanium alloy composition to a temperature lower than 500° C. at an average cooling rate greater than 10° C./second between the beta transition temperature and 500° C., so that the quenched work piece contains β phase with a body-centered cubic crystal structure as a major phase; and II) polishing the quenched work piece so that a surface of the polished work piece has an average surface roughness less than about 0.1 μm.    
   
   
       19 . The method of  claim 18 , wherein said titanium alloy composition further comprises at least one eutectoid beta stabilizing element selected from the group consisting of Fe, Cr, Mn, Co, Ni, Cu, Ag, Au, Pd, Si and Sn.  
   
   
       20 . The method of  claim 18 , wherein said titanium alloy composition consists essentially of 0.1-3 wt % Bi, 10-50 wt % of at least one alloy element selected from the group consisting of Mo, Nb, Ta, Zr and Hf, based on the weight of the composition, and the balance Ti.