Non-equilibrium alloy cold spray feedstock powders, manufacturing processes utilizing the same, and articles produced thereby

Abstract

Methods for producing Non-Equilibrium Alloy (NEA) feedstock powders are disclosed, as are methods for fabricating articles from such NEA feedstock powders utilizing Additive Manufacturing (AM) cold spray processes. In various embodiments, the method includes the step or process obtaining an NEA feedstock powder, which is composed of an alloy matrix throughout which a first minority constituent is dispersed. The first minority constituent precipitates from the alloy matrix when the NEA feedstock powder is exposed to temperatures exceeding a critical temperature threshold (T CRITICAL ) for a predetermined time period. An AM cold spray process is carried-out to produce a near-net article from the NEA feedstock powder, which is exposed to a maximum temperature (T SPRAY _ MAX ) during the cold spray process. The near-net article is then further processed to yield a finished article. To substantially preserve the non-equilibrium state of the feedstock powder, T SPRAY _ MAX is maintained below T CRITICAL through the cold spray process.

What is claimed is: 
     
         1 . A method, comprising:
 obtaining a Non-Equilibrium Alloy (NEA) feedstock powder composed of an alloy matrix and throughout which a first minority constituent is dispersed, the first minority constituent precipitating from the alloy matrix when the NEA feedstock powder is exposed to temperatures exceeding a critical temperature threshold (T CRITICAL ) for a predetermined time period;   utilizing an Additive Manufacturing (AM) cold spray process to fabricate a near-net article from the NEA feedstock powder; and   further processing the near-net article to yield a finished article;   wherein the near-net article is exposed to a maximum temperature (T SPRAY   _   MAX ) during the cold spray process; and   wherein T SPRAY   _   MAX  is maintained below T CRITICAL  to preserve, at least in substantial part, a non-equilibrium state of the NEA feedstock powder through the cold spray process.   
     
     
         2 . The method of  claim 1  wherein T CRITICAL  is less than a melt point of the NEA feedstock powder and greater than 300 degrees Celsius. 
     
     
         3 . The method of  claim 1  wherein further processing comprises:
 subjecting the near-net article to a post-spray annealing process following the AM cold spray process; and 
 machining selected surfaces of the near-net article after the post-spray annealing process; 
 wherein, during the post-spray annealing and machining process steps, the near-net article is exposed to maximum temperatures less than T CRITICAL . 
 
     
     
         4 . The method of  claim 3  wherein the near-net article is exposed to a maximum annealing temperature (T ANNEAL ) during the post-spray annealing process; and
 wherein T ANNEAL  is greater than ½ T CRITICAL  and less than T CRITICAL . 
 
     
     
         5 . The method of  claim 1  further comprising selecting the NEA feedstock powder such that:
 the NEA feedstock powder is composed predominately of aluminum by weigh percent; and 
 the first minority constituent is selected from the group consisting of iron and silicon. 
 
     
     
         6 . The method of  claim 1  further comprising selecting the NEA feedstock powder to contain, by weight percent:
 between 85 and 90 aluminum; 
 between 8 and 10 percent iron; 
 between 1 and 3 percent silicon; and 
 between 1 and 2 percent vanadium. 
 
     
     
         7 . The method of  claim 1  further comprising selecting the NEA feedstock to have a particle size ranging from approximately 10 to approximately 140 microns in maximum dimension. 
     
     
         8 . The method of  claim 1  further comprising selecting the NEA feedstock powder to consist substantially entirely of flake-shaped particles ranging from approximately 10 microns to approximately 90 microns in maximum dimension. 
     
     
         9 . The method of  claim 1  wherein the NEA feedstock powder is produced utilizing a process comprising:
 forming a molten alloy into a solid shape utilizing a casting process having a cooling rate equal to or greater than approximately 1×10 6  degrees Celsius per second; and 
 mechanically converting the solid shape into the NEA feedstock powder. 
 
     
     
         10 . The method of  claim 9  wherein forming comprising forming the molten alloy into a ribbon utilizing a planar flow casting process having a cooling rate equal to or greater than approximately 1×10 7  degrees Celsius per second. 
     
     
         11 . The method of  claim 9  wherein mechanically converting comprises:
 chopping the solid shape into flake-shaped pieces having an average size range; and 
 attrition milling the flake-shaped pieces to reduce an average size range thereof. 
 
     
     
         12 . The method of  claim 1  wherein the NEA feedstock particles are subjected to a pre-spray anneal process having a maximum anneal temperature (T ANNEAL   _   MAX ) prior to the AM cold spray process; and
 wherein T ANNEAL   _   MAX  is less than T CRITICAL . 
 
     
     
         13 . The method of  claim 1  wherein the finished article comprises a gas turbine engine component;
 wherein, during the AM cold spray process, the NEA feedstock powder is deposited around a sacrificial structure; and 
 wherein further processing comprises removing the sacrificial structure to create a flow passage through the gas turbine engine component. 
 
     
     
         14 . A method, comprising:
 forming a molten alloy into a solid Non-Equilibrium Alloy (NEA) body utilizing a casting process having a cooling rate equal to or greater than approximately 1×10 6  degrees Celsius per second;   mechanically converting the solid NEA body into a NEA feedstock powder; and   subjecting the feedstock powder to an anneal processing having a maximum anneal temperature (T ANNEAL   _   MAX );   wherein the NEA feedstock powder comprises an alloy matrix throughout which a first minority constituent is dispersed;   wherein the first minority constituent precipitates from the alloy matrix when the NEA feedstock powder is exposed to temperatures exceeding a critical temperature threshold T CRITICAL  for a predetermined time period; and   wherein T CRITICAL  is less than a melt point of the NEA feedstock powder and greater than T ANNEAL   _   MAX .   
     
     
         15 . The method of  claim 14  wherein forming comprises forming the molten alloy into an NEA ribbon utilizing a planar flow casting process having a cooling rate equal to or greater than approximately 1×10 7  degrees Celsius per second. 
     
     
         16 . The method of  claim 14  wherein mechanically converting comprises mechanically converting the solid NEA body into a NEA feedstock powder consisting substantially entirely of flake-shaped particles ranging from approximately 10 microns to approximately 90 microns in maximum dimension. 
     
     
         17 . The method of  claim 14  further comprising formulating the NEA feedstock powder such that:
 the NEA feedstock powder is predominately composed of a first material by weight percent, the first material selected from the group consisting of aluminum and nickel; and 
 the first minority constituent forms dispersoids within the NEA feedstock powder, the dispersoids selected from the group consisting of silicide dispersoids and carbide dispersoids. 
 
     
     
         18 . The method of  claim 14  further comprising formulating the NEA feedstock powder such that T CRITICAL  is between about 400 degrees Celsius and about 450 degrees Celsius. 
     
     
         19 . A method, comprising:
 utilizing an Additive Manufacturing (AM) cold spray process to fabricate a near-net article from a Non-Equilibrium Alloy (NEA) feedstock powder having a melt point (T ALLOY   _   MP ), the NEA feedstock powder comprising:
 an aluminum alloy matrix; and 
 a non-trace amount of silicon contained in the aluminum alloy matrix and precipitating therefrom when the NEA feedstock powder is exposed to temperatures exceeding a critical temperature threshold (T CRITICAL ) for a predetermined time period; 
   after utilizing the AM cold spray process to fabricate the near-net article from a NEA feedstock powder, annealing the near-net article at a maximum annealing temperature (T ANNEAL );   wherein the steps of utilizing and annealing are performed such that T ANNEAL <T CRITICAL <T ALLOY   _   MP .   
     
     
         20 . The method of  claim 19  wherein T ANNEAL   _   MAX  is greater than T CRITICAL  minus 150 degrees Celsius and less than T CRITICAL  minus 25 degrees Celsius.