Method and composition for metal free form fabrication

Abstract

A method of direct metal fabrication to form a metal part which has a relative density of at least 96%. There is provided a powder blend which comprises a parent metal alloy, a powdered lower-melting-temperature alloy that comprises greater than 10% of total weight of the powder blend, and an organic polymer component (a thermoplastic polymer and a thermosetting polymer) that comprises less than 3% by weight of a total weight of the powdered blend. There is a laser-build powder processing operation (a selective laser sintering (SLS) operation) to fabricate a green body. The green body is then placed in a furnace and the temperature raised to sufficiently high temperature to perform a supersolidus liquid phase sintering operation to form the metal part.

1 . A method of direct metal fabrication to form a metal part which has a relative density of at least 96%, said method comprising: 
 a) providing a powder blend which comprises a powdered parent metal alloy, a powdered lower-melting-temperature alloy that comprises greater than 10% of the total weight of the powdered blend, and an organic polymer component that comprise less than 3% by weight of the total weight of the powdered blend;    b) performing a layer-build powder processing operation to fabricate a green body by laying down successive layers of the powder blend and sintering the layers in accordance with a predetermined pattern;    c) positioning the green part in a chamber of the furnace and raising the temperature in the chamber to reduce the organic polymer and then accomplish a supersolidus liquid phase sintering operation to form the metal part that by sinter densification obtains a relative density of at least 96%.    
     
     
         2 . The method of  claim 1 , wherein said polymer comprises two polymers.  
     
     
         3 . The method as recited in  claim 2 , wherein said two polymers comprise a thermoplastic polymer and a thermosetting polymer.  
     
     
         4 . The method as recited in  claim 3 , wherein said layer-build powder processing operation comprises a selective laser sintering (SLS) operation.  
     
     
         5 . The method as recited in  claim 1 , wherein said layer build powder processing operation comprises a selective laser sintering (SLS) operation.  
     
     
         6 . The method as recited in  claim 4 , wherein the particle size of the parent metal alloy and a lower-melting-temperature alloy are about of a particle size such that the particles pass a 270 mesh screen.  
     
     
         7 . The method as recited in  claim 4 , wherein particles of the parent metal alloy and a lower-melting-temperature alloy are about of a particle size such that the particles pass a 140 mesh screen.  
     
     
         8 . The method as recited in  claim 4 , wherein particles of the parent metal alloy and a lower-melting-temperature alloy are about of a particle size that the particles pass a 325 mesh screen.  
     
     
         9 . The method as recited in  claim 1 , wherein particles of the parent metal alloy and a lower-melting-temperature alloy are about of a particle size that the particles pass a 400 mesh screen.  
     
     
         10 . The method as recited in  claim 1 , wherein the supersolidus liquid phase sintering operation occurs predominately in a temperature range between greater than about 2248° F. and less than about 2267° F.  
     
     
         11 . The method as recited in  claim 4 , wherein the supersolidus liquid phase sintering operation occurs predominately in a temperature range between about 2252° F. to about 2260° F.  
     
     
         12 . The method as recited in  claim 4 , wherein said lower-melting-temperature alloy contains a eutectic ingredient selected from boron, manganese, yttrium, niobium, silicon, cobalt, and combinations of these.  
     
     
         13 . The method as recited in  claim 4 , wherein said lower-melting-temperature alloy contains a eutectic ingredient which substantially comprises boron.  
     
     
         14 . The method as recited in  claim 4 , wherein said parent metal alloy comprises predominately a primary ingredient selected from nickel, iron, cobalt, copper, tungsten, molybdenum, rhenium, titanium, aluminum, and mixtures thereof.  
     
     
         15 . The method as recited in  claim 4 , wherein the parent metal alloy comprises primarily nickel.  
     
     
         16 . The method as recited in  claim 4 , wherein said parent metal alloy comprises primarily a 230 alloy.  
     
     
         17 . The method as recited in  claim 4 , wherein the powdered organic polymer comprises no greater than about 2% by weight of the total weight of the powdered blend.  
     
     
         18 . The method as recited in  claim 4 , wherein the powdered organic polymer comprises no greater than about 1% by weight of the total weight of the powdered blend.  
     
     
         19 . The method as recited in  claim 4 , wherein the powdered organic polymer comprises no greater than about 1 /200 of weight of the total weight of the powdered blend.  
     
     
         20 . The method as recited in  claim 4 , wherein the green body which is made by the selective laser sintering operation has a relative density of at least 58%.  
     
     
         21 . The method as recited in  claim 4 , wherein: 
 a) a substantial portion of the particles of the parent metal alloy and a lower-melting-temperature alloy are of a particle size that the particles pass a 140 mesh screen;    b) the supersolidus liquid phase sintering operation occurs predominately in a temperature range greater than between 2248° F. and less than 2267° F.;    c) said lower-melting-temperature alloy contains a eutectic ingredient selected from boron, manganese, yttrium, niobium, silicon, cobalt, and combinations of these.    
     
     
         22 . The method as recited in  claim 19 , wherein said parent metal alloy comprises predominately a primary ingredient selected from nickel, iron, cobalt, copper, tungsten, molybdenum, rhenium, titanium, aluminum, and mixtures thereof.  
     
     
         23 . The method as recited in  claim 4 , wherein: 
 a) particles of the parent metal alloy and a lower-melting-temperature alloy are of a particle size that the particles pass a 270 mesh screen;    b) the supersolidus liquid phase sintering operation occurs predominately in a temperature range between about 2252° F. to about 2260° F.;    c) the powdered organic polymer comprises no greater than about 1% by weight of the total weight of the powdered blend.    
     
     
         24 . The method as recited in  claim 23 , wherein the parent metal alloy comprises primarily nickel.  
     
     
         25 . The method as recited in  claim 4 , wherein said parent metal alloy comprises primarily a 230 alloy.  
     
     
         26 . The method as recited in  claim 4 , wherein the ratio of the amount of powdered low-melting-temperature alloy to the amount of the powdered organic polymer is by weight is at least as great than 5:1.  
     
     
         27 . The method as recited in  claim 4 , wherein the ratio of the amount of powdered low-melting-temperature alloy to the amount of the powdered organic polymer is by weight at least as great as 10:1  
     
     
         28 . The method as recited in  claim 4 , wherein the ratio of the amount of powdered low-melting-temperature alloy to the amount of the powdered organic polymer is by weight at least as great as 30:1.  
     
     
         29 . The method as recited in  claim 4 , wherein there is in the chamber of the furnace at least during the supersolidus liquid phase sintering a gaseous atmosphere of hydrogen and an inert gas in a ratio of no greater than about 1 to 19, measured by volume at the same temperature and pressure.  
     
     
         30 . The method as recited in  claim 29 , wherein said ratio is about 1 to 19.  
     
     
         31 . The method as recited in  claim 29 , wherein said inert gas comprises argon.  
     
     
         32 . A metal part made according to the method of  claim 1 .  
     
     
         33 . A powdered composition adapted to be used in direct metal fabrication to form a metal part which has a relative density of at least 96%, wherein the metal part is formed by: 
 a) performing a laser-build powder processing operation to fabricate a green body by laying down successive layers of the powdered composition and laser sintering the layers in accordance with a predetermined pattern;    b) positioning the green part in a chamber of the furnace and raising the temperature in the chamber to reduce the organic polymer and then accomplish a supersolidus liquid phase sintering operation to form the metal part that by sinter densification obtains a relative density of at least 96%,    said powdered composition comprising a powder blend which comprises a powdered parent metal alloy, a powdered lower-melting-temperature alloy that comprises greater than 10% of the total weight of the powdered blend, and a powdered organic polymer component that comprises less than 3% by weight of the total weight of the powdered blend.    
     
     
         34 . A method as recited in  claim 33 , wherein said polymer component comprises a thermoplastic polymer and a thermosetting polymer.