Structural direct-write additive manufacturing of molten metals

Abstract

An alloy for structural direct-writing additive manufacturing comprising a base element selected from the group consisting of aluminum (Al), nickel (Ni) and a combination thereof, and a rare earth element selected from the group consisting of cerium (Ce), lanthanide (La) and a combination thereof, and a eutectic intermetallic present in said alloy in an amount ranging from about 0.5 wt. % to 7.5 wt. %. The invention is also directed to a method of structural direct-write additive manufacturing using the above-described alloy, as well as 3D objects produced by the method. The invention is also directed to methods of producing the above-described alloy.

What is claimed is: 
     
         1 . An alloy for structural direct-writing additive manufacturing comprising a base element selected from the group consisting of aluminum (Al), nickel (Ni) and a combination thereof, and a rare earth element selected from the group consisting of cerium (Ce), lanthanide (La) and a combination thereof, and a eutectic intermetallic present in said alloy in an amount ranging from about 0.5 wt. % to 7.5 wt. %. 
     
     
         2 . The alloy of  claim 1 , wherein said rare earth element is Ce, wherein said Ce is present in said alloy in an amount up to 8 wt. %. 
     
     
         3 . The alloy of  claim 1 , wherein said rare earth element is La, wherein said La is present in said alloy in an amount up to 10 weight percent %. 
     
     
         4 . The alloy of  claim 1 , wherein said alloy further comprises at least one additional alloying element selected from the group consisting of iron (Fe), silicon (Si) and magnesium (Mg). 
     
     
         5 . The alloy of  claim 4 , wherein Fe is present in said alloy in an amount up to 2 wt. %, Si is present in said alloy in an amount up to 2 wt. %, and Mg is present in said alloy in an amount up to 30 wt. %. 
     
     
         6 . The alloy of  claim 1 , wherein said alloy further comprises an additive selected from the group consisted of SiC, carbon nanotube (CNT), alumina and boron nitride. 
     
     
         7 . The alloy of  claim 6 , wherein said additive is present in said alloy in an amount up to 30 vol %. 
     
     
         8 . The alloy of  claim 1 , wherein said alloy is an Al—Ce alloy, with said Ce present in an amount of about 0.5 to 7 wt. % by weight of said alloy, and said eutectic intermetallic is Al 11 Ce 3 . 
     
     
         9 . The alloy of  claim 1 , wherein said alloy is an Al—La alloy, and said eutectic intermetallic is Al 11 La 3 . 
     
     
         10 . The alloy of  claim 1 , further comprising discrete units of said alloy interconnected by an interface containing said eutectic intermetallic, wherein said eutectic intermetallic is present at said interface in an amount greater than that within each of said discrete units. 
     
     
         11 . A method of fabricating a three-dimensional (3D) metallic object using direct-write additive manufacturing, the method comprising the steps of:
 a. providing an alloy comprising a base element selected from the group consisting of aluminum (Al), nickel (Ni) and a combination thereof, and a rare earth element selected from the group consisting of cerium (Ce), lanthanide (La) and a combination thereof, and a eutectic intermetallic present in said alloy in an amount ranging from about 0.5 wt. % to 7.5 wt. %;   b. heating said alloy to a temperature within 15% above or below a melting point of said alloy in an inert atmosphere;   c. extruding said alloy through a nozzle in the presence of an oxygen-containing atmosphere, including but not limited to ambient atmosphere, to form beads of said alloy having a surface tension ranging from about 0.3 N/m to 2.0 N/m, wherein before exiting said nozzle said alloy remains in said inert atmosphere, and a stabilizing shell is formed surrounding a liquid core of each of said beads when said beads are exposed to said oxygen-containing atmosphere, wherein said stabilizing shell comprises oxides of alloying elements of said alloy and at least one metastable intermetallic of the alloying elements; and   d. depositing said beads on a substrate and contacting said beads with each other, wherein said stabilizing shells of adjacent beads fuse on contact as said beads are cooled down in said oxygen-containing atmosphere, wherein during the fusing of the beads, said eutectic intermetallic is formed at an interface of said adjacent beads in an amount greater than that within each of said adjacent beads.   
     
     
         12 . The method of  claim 11 , wherein said Alloy is an Al—Ce alloy, and said eutectic intermetallic is Al 11 Ce 3 . 
     
     
         13 . The method of  claim 12 , wherein at least one metastable intermetallic is present in said stabilizing shell, and the at least one metastable intermetallic comprises Al 2 Ce or Al 4 Ce. 
     
     
         14 . The method of  claim 11 , wherein said alloy is an Al—La alloy, and said eutectic intermetallic is Al 11 La 3 . 
     
     
         15 . The method of  claim 11 , wherein said alloy further comprises at least one additional alloying element selected from the group consisting of iron (Fe), silicon (Si), and magnesium (Mg). 
     
     
         16 . The method of  claim 11 , wherein said stabilizing shell has a thickness ranging from about 10 to 15 nm. 
     
     
         17 . The method of  claim 11 , wherein said at least one metastable intermetallic is present in said stabilizing shell, and the at least one metastable intermetallic has a rare earth content different than a rare earth content in said eutectic intermetallic 
     
     
         18 . The method of  claim 11 , wherein during said fusion, said oxide of said rare earth element in said stabilizing shells of adjacent beads dissolves and forms said eutectic intermetallic at said interface. 
     
     
         19 . The method of  claim 11 , wherein during said fusion, said at least one metastable intermetallic is present in said stabilizing shells of adjacent beads, and then decomposes and forms said eutectic intermetallic at said interface. 
     
     
         20 . The method of  claim 11 , wherein in step (d) said beads are deposited in a layer-on-layer manner on said substrate to form said 3D metallic object, wherein said stabilizing shells of said beads in adjacent layers fuse on contact as said beads are cooled down in said oxygen-containing atmosphere, thereby welding said adjacent layers, wherein, during said fusion, said eutectic intermetallic is formed at an interface of said adjacent layer in an amount greater than that within each of said layers.