A method of fabricating three-dimensional parts out of an alloy of aluminum and titanium

Abstract

A method of fabricating a sintered three-dimensional part, the method including: preparing an injection composition including a binder and a powder of a titanium-based alloy including aluminum and/or chromium; injecting the composition into a cavity of a mold to obtain a blank; eliminating the binder present in the blank; a first step of sintering the powder, the powder subjected to a first pressure higher than or equal to 1 mbar to obtain a preform of the part; and a second sintering step during which a second pressure, which is lower than the first pressure, is imposed, the duration for which the second pressure is applied being selected so that the content by weight of aluminum and/or chromium in a layer having a thickness of 200 μm situated at the surface of the preform does not vary by more than 5% in relative value due to the second sintering step.

1 . A method of fabricating a sintered three-dimensional part comprising a titanium-based alloy, the method comprising:
 preparing an injection composition comprising a binder and a powder of a titanium-based alloy including aluminum and/or chromium as alloying addition element(s);   injecting the injection composition into a cavity of a mold so as to obtain a blank for the part to be made;   selectively eliminating the binder present in the blank;   a first step of sintering the powder of titanium-based alloy, the powder being subjected during the first sintering step to a first pressure that is higher than or equal to 1 mbar in order to obtain a preform of the part made of sintered alloy powder; and   a second sintering step, performed after the first sintering step, during which a second pressure is imposed, the second pressure being lower than the first pressure, the duration for which the second pressure is applied being selected so that the content by weight of aluminum and/or chromium in a layer having a thickness of 200 μm situated at the surface of the preform does not vary by more than 5% in relative value as a result of the second sintering step.   
     
     
         2 . A method according to  claim 1 , wherein the second pressure is lower than 1 mbar. 
     
     
         3 . A method according to  claim 1 , further including, after the second sintering step, a third sintering step during which a third pressure is imposed, the third pressure being higher than the second pressure. 
     
     
         4 . A method according to  claim 3 , wherein the third pressure is higher than or equal to 1 mbar. 
     
     
         5 . A method according to  claim 1 , wherein the part obtained is a turbine engine blade. 
     
     
         6 . A method according to  claim 1 , wherein the content by weight of aluminum in the alloy powder is greater than 10% prior to the first sintering step. 
     
     
         7 . A method according to  claim 1 , wherein the alloy powder prior to the first sintering step presents the following contents by weight of the following elements:
 32% to 33.5% aluminum;   4.5% to 5.1% niobium; and   2.4% to 2.7% chromium.   
     
     
         8 . A method according to  claim 1 , wherein the alloy powder prior to the first sintering step presents the following contents by weight of the following elements:
 28.12% to 29.12% aluminum;   8.56% to 9.56% niobium; and   1.84% to 2.84% molybdenum.   
     
     
         9 . A method according to  claim 1 , wherein the alloy powder prior to the first sintering step presents the following contents by weight of the following elements:
 5.4% to 6.6% aluminum; and   3.6% to 4.4% vanadium.