Alloying System

Abstract

An alloying system for preparing a titanium alloy, the system comprising a rotating mill to mechanically alloy a mixture of elemental powders in predetermined proportions, the elemental powders including titanium particles, alpha stabilizer particles and beta stabilizer particles; wherein the mixture is mechanically alloyed using low impact energy to layer the titanium particles with beta stabilizer particles whereby sintering of the mechanically alloyed mixture produces alternate layers of alpha and beta stabilizer particles.

1 . An alloying system for preparing a titanium alloy, the system comprising: 
 a rotating mill to mechanically alloy a mixture of elemental powders in predetermined proportions, the elemental powders including titanium particles, alpha stabilizer particles and beta stabilizer particles;    wherein the mixture is mechanically alloyed using low impact energy to layer the titanium particles with beta stabilizer particles whereby sintering of the mechanically alloyed mixture produces alternate layers of alpha and beta stabilizer particles.    
     
     
         2 . The system according to  claim 1 , wherein the rotating mill is a tumbler mill.  
     
     
         3 . The system according to  claim 2 , wherein the tumbler mill has a charge to ball ratio of 1:2 in volume.  
     
     
         4 . The system according to  claim 2 , wherein the tumbler mill uses Al 2 O 3  balls.  
     
     
         5 . The system according to  claim 4 , wherein the balls have a diameter of 5, 10 and 20 mm and are in the ratio of 40:40:20, respectively.  
     
     
         6 . The system according to  claim 2 , wherein the speed of the tumbler mill is 65 to 70 revolutions per minute.  
     
     
         7 . The system according to  claim 1 , wherein the beta stabilizer particles include an amount of 1 to 5% by weight of zirconium as an isomorphous stabilizer.  
     
     
         8 . The system according to  claim 1 , wherein the beta stabilizer particles include an amount of 1 to 2% by weight of iron as an eutectold stabilizer.  
     
     
         9 . The system according to  claim 1 , wherein the alpha stabilizer particles include an amount of 2 to 4% by weight of aluminium.  
     
     
         10 . The system according to  claim 1 , wherein the mixture of elemental powders is mechanically alloyed in an inert gas atmosphere.  
     
     
         11 . The system according to  claim 1 , wherein the impact energy rate of the rotating mill is in the range of 0 to 1 Joules/hit.  
     
     
         12 . The system according to  claim 1 , wherein the impact rate of the rotating mill is of a substantially equal magnitude to the rotational speed of the rotating mill.  
     
     
         13 . The system according to  claim 2 , wherein the tumbler mill has a 100 mm diameter drum.  
     
     
         14 . The system according to  claim 13 , wherein the path of the drum is a helix to ensure uniformity.  
     
     
         15 . The system according to  claim 13 , wherein the centre points of the top and bottom of the drum are rotated asynchronously In an ellipsoidal orbit to force the powders and balls to move within the drum such that the balls impact on a new surface for every rotation.  
     
     
         16 . The system according to  claim 10 , wherein the inert gas atmosphere is argon.  
     
     
         17 . A method for preparing a titanium alloy, the method comprising: 
 mechanically alloying a mixture of elemental powders in predetermined proportions, the elemental powders including titanium particles, alpha stabilizer particles and beta stabilizer particles;    wherein the mixture is mechanically alloyed using low impact energy to layer the titanium particles with beta stabilizer particles whereby sintering of the mechanically alloyed mixture produces alternate layers of alpha and beta stabilizer particles.    
     
     
         18 . The method according to  claim 17 , further comprising the step of sieving the mechanically alloyed mixture.  
     
     
         19 . The method according to  claim 18 , wherein a 325 mesh sieve is used to remove the balls and contaminants from the mechanically alloyed mixture.  
     
     
         20 . The method according to  claim 17 , further comprising the step of compacting the mechanically alloyed mixture into a preform.  
     
     
         21 . The method according to  claim 20 , wherein the mixture is compacted to tensile bars and 10 mm die pellets.  
     
     
         22 . The method according to  claim 20 , further comprising the step of sintering the preform to consolidate the mechanically alloyed mixture.  
     
     
         23 . The method according to  claim 22 , wherein the preform is sintered at a temperature ranging from 10° C. to 1300° C.  
     
     
         24 . The method according to  claim 22 , wherein the preform is sintered for one to two hours  
     
     
         25 . The method according to  claim 24 , wherein sintering occurs in an inert gas atmosphere.  
     
     
         26 . The method according to  claim 22 , further comprising the step of isothermally forging the sintered preform into a predetermined shape.  
     
     
         27 . The method according to  claim 26 , wherein the sintered preform is isothermally forged at a temperature ranging from 200° C. to 350° C.  
     
     
         28 . The method according to  claim 26 , wherein the sintered preform is forged at a stress rate ranging from 0.6 to 1 bar/second.  
     
     
         29 . The method according to  claim 26 , wherein the sintered preform is forged using a lubricant.  
     
     
         30 . The method according to  claim 29 , wherein the lubricant is graphite or molybdenum disulphide.  
     
     
         31 . The method according to  claim 17 , wherein the beta stabilizer particles include an amount of 1 to 5% by weight of zirconium as an isomorphous stabilizer.  
     
     
         32 . The method according to  claim 17 , wherein the beta stabilizer particles include an amount of 1 to 2% by weight of iron as an eutectoid stabilizer.  
     
     
         33 . The method according to  claim 17 , wherein the alpha stabilizer particles include an amount of 2 to 4% by weight of aluminium.  
     
     
         34 . A titanium-base alloy prepared according to the method of  claim 17 , the alloy consisting essentially of the following alloying components: 
 an amount from about 1 to about 5% by weight of zirconium;    an amount from about 1 to about 2% by weight of iron; and    an amount from about 2 to about 4% by weight of aluminum.