Method for manufacturing a metal part made from titanium, by rapid sintering, and sintered metal part made from titanium

Abstract

Disclosed is a method for manufacturing a metal part made from titanium, by sintering a powder, the method comprising a step of mixing a spherical titanium powder and a dendritic titanium powder in order to form a mixture, a step of agglomerating the mixture of titanium powders by compaction with a ram moving at a speed of more than 2 m·s −1 , the mixture of titanium powders being free of binders, in particular organic binders, forming a green body or agglomerate suitable for sintering having a density above 78%, and preferably 80%, of the density of the solid metal, and a step of sintering.

1 . A method for manufacturing a titanium-based metal part, by sintering a powder, the method comprising:
 mixing a spherical titanium powder and a dendritic titanium powder to form a mixture,   agglomerating the titanium powder mixture by compaction with a ram moving at a speed greater than 2 m·s −1 , the titanium powder mixture being devoid of binder,   forming a green body or agglomerate suitable for sintering having a density greater than 78% of the density of the solid metal, and a   sintering the green body.   
     
     
         2 . The method according to  claim 1 , comprising before mixing:
 providing from 60 to 90% by mass of spherical titanium powder and from 10 to 40% by mass of dendritic titanium powder, wherein the green body has a green strength greater than 3 MPa.   
     
     
         3 . The method according to  claim 1 , wherein the ram exerts a pressure between 600 and 1500 MPa. 
     
     
         4 . The method according to  claim 1 , wherein the ram moves at a speed greater than 4 m·s −1 . 
     
     
         5 . The method according to  claim 1 , wherein sintering the green body is performed in a neutral to reducing atmosphere, at a pressure less than 0.13 Pa (10 −4  Torr) and at a temperature between 1200° C. and 1350° C. to obtain a sintered body. 
     
     
         6 . The method according to  claim 5 , wherein the sintering pressure is greater than 0.13 mPa (10 −7  Torr). 
     
     
         7 . The method according to  claim 5 , wherein sintering the green body is conducted until a density greater than 97% of the density of the solid metal is obtained, particularly for over 4 hours. 
     
     
         8 . The method according to  claim 1 , further comprising:
 cooling at a pressure less than 0.13 Pa (10 −4  Torr) of a duration between 12 and 48 hours.   
     
     
         9 . The method according to  claim 1 , wherein the spherical titanium powder is obtained by plasma atomization, by gas atomization or by a plasma rotating electrode process, and has a grain size less than 150.10 −6  m, and the dendritic titanium powder is obtained by the sodium metal iodide reduction process and has a grain size less than 100.10 −6  m. 
     
     
         10 . The method according to  claim 1 , further comprising, before mixing,
 providing from 40 to less than 90% by mass of spherical titanium powder and from 60 to more than 10% by mass of dendritic titanium powder.   
     
     
         11 . Titanium-based sintered metal part, of density greater than 97%, of the density of the solid metal, wherein the sintered metal part is produced by the method according to  claim 1 . 
     
     
         12 . The sintered metal part according to  claim 11 , comprising by mass, from 5.50 to 6.75% Al, from 3.50 to 4.50% V, less than 0.20% Fe, less than 0.04% C, less than 0.03% N, less than 0.005% H, less than 0.02% O, the remainder being Ti and unavoidable impurities and having a Young's modulus greater than 820 N·mm −2 , and an elongation greater than 10%. 
     
     
         13 . The sintered metal part according to  claim 11 , comprising by mass, less than 0.002% Fe, less than 0.01% C, less than 0.02% N, less than 0.01% H, less than 0.1% O, the remainder being Ti and unavoidable impurities and having a Young's modulus greater than 748 N·mm −2  and an elongation greater than 18%. 
     
     
         14 . The sintered metal part according to  claim 11 , comprising by mass less than 0.02% O.