Methods and tools for friction extrusion of composite extrudates

Abstract

A tool assembly for friction extrusion can comprise a friction extrusion die. The friction extrusion die can include a distal face and a proximal end. The distal face can define at least one topographical ridge or groove feature to induce plasticization of a material in response to an axial force and a rotational force applied by the distal face to the material. The friction extrusion die can define a central passage to carry an extrudate of the material in a proximal direction in response to the applied axial and rotational forces. The proximal end can define a faceted cross-sectional profile to mate a with a corresponding receiving end of a tool holder. The faceted cross-sectional profile can be sized and shaped to receive the rotational force through engagement by the tool holder of respective faces defined by the faceted cross-sectional profile.

What is claimed is: 
     
         1 . A tool assembly for friction extrusion, the tool assembly comprising:
 a friction extrusion die comprising:   a distal face defining at least one topographical ridge or groove feature to induce plasticization of a material in response to an axial force and a rotational force applied by the distal face to the material, the friction extrusion die defining a central passage to carry an extrudate of the material in a proximal direction in response to the applied axial and rotational forces; and   a proximal end defining a faceted cross-sectional profile to mate a with a corresponding receiving end of a tool holder, the faceted cross-sectional profile sized and shaped to receive the rotational force through engagement by the tool holder of respective faces defined by the faceted cross-sectional profile.   
     
     
         2 . The tool assembly of  claim 1 , wherein the faceted cross-sectional profile of the proximal end of the friction extrusion die is configured to mate with a receiving end of the tool holder. 
     
     
         3 . The tool assembly of  claim 2 , wherein the receiving end of the tool holder defines a socket configured to mate with the faceted cross-sectional profile of the proximal end of the friction extrusion die, wherein respective inward-facing faces of the socket extend inward toward a longitudinal central axis of the socket to provide the engagement by the tool holder of the respective faces of defined by the faceted cross-sectional profile. 
     
     
         4 . The tool assembly of  claim 2 , wherein vertices of the respective faces defined by the faceted cross-sectional profile extend outward away from a longitudinal central axis to enable the engagement by the tool holder of the respective faces. 
     
     
         5 . The tool assembly of  claim 1 , wherein the faceted cross-sectional profile is polygonal. 
     
     
         6 . The tool assembly of  claim 1 , wherein the faceted cross-sectional profile is defined by an outer surface of the proximal end of the friction extrusion die. 
     
     
         7 . The tool assembly of  claim 6 , wherein the outer surface of the proximal end of the friction extrusion die defines a protrusion with the faceted cross-sectional profile. 
     
     
         8 . A method of friction extruding, the method comprising:
 receiving iron feedstock including one or more non-ferritic elements; and   applying an axial force and a rotational force, applied via a distal face of a die, to the iron feedstock for plasticizing the iron feedstock to generate an iron alloy extrudate from the iron feedstock.   
     
     
         9 . The method of  claim 8 , wherein the applying the axial force and the rotational force incudes using a friction extrusion die comprising:
 the distal face defining at least one topographical ridge or groove feature to induce plasticization of a material in response to the axial force and the rotational force applied by the distal face to the material, the die defining a central passage to carry an extrudate of the material in a proximal direction in response to the applied axial and rotational forces; and   a proximal end defining a faceted cross-sectional profile to mate a with a corresponding receiving end of a tool holder, the faceted cross-sectional profile sized and shaped to receive the rotational force through engagement by the tool holder of respective faces defined by the faceted cross-sectional profile.   
     
     
         10 . The method of  claim 8 , wherein the received iron feedstock comprises an oxide dispersion strengthened (ODS) alloy precursor, the ODS alloy precursor produced at least in part using a gas atomization process, the gas atomization process including use of a gas mixture comprising oxygen. 
     
     
         11 . The method of  claim 10 , wherein the one or more non-ferritic elements comprise at least one of yttrium, titanium, or oxygen. 
     
     
         12 . The method of  claim 10 , wherein the iron alloy extrudate is an ODS iron alloy comprising:
 bulk material; and   nanoparticle precipitates dispersed in the bulk material, the nanoparticle precipitates having relatively higher atomic percentages of non-ferritic elements comprising at least one of titanium, oxygen, or yttrium, in comparison with the bulk material, the nanoparticle precipitates having a density within a range of 10 22 /m 3  to 10 23 /m 3  dispersed in the bulk material, and wherein the bulk material has a relatively higher atomic percentage of iron than the nanoparticle precipitates.   
     
     
         13 . The method of  claim 12 , the ODS iron alloy having a fracture toughness exceeding 250 megapascals by square root meter (MPa·m 1/2 ) at room temperature. 
     
     
         14 . The method of  claim 8 , wherein the received iron feedstock has been generated from iron ore, the iron feedstock comprising iron pellets, the iron pellets being at least 70 weight percent iron. 
     
     
         15 . The method of  claim 14 , wherein the one or more non-ferritic elements comprise at least one of silica or alumina. 
     
     
         16 . The method of  claim 9 , wherein the iron alloy extrudate is a high strength sponge iron, the high strength sponge iron having a yield strength within a range of 40 to 50 kilo-pounds per square inch (ksi) at room temperature. 
     
     
         17 . The method of  claim 9 , wherein the iron alloy extrudate is a high strength sponge iron, the high strength sponge iron having a hardness within a range of 300 to 400 Vickers Pyramid Number (HV). 
     
     
         18 . A friction extrusion comprising:
 an oxide dispersion strengthened (ODS) iron alloy having a fracture toughness exceeding 250 megapascals by square root meter (MPa·m 1/2 ) at room temperature, the ODS iron alloy comprising:   bulk material; and   nanoparticle precipitates dispersed in the bulk material, the nanoparticle precipitates having relatively higher atomic percentages of non-ferritic elements including at least one of titanium, oxygen, or yttrium, in comparison with the bulk material, and wherein the bulk material has a relatively higher atomic percentage of iron in comparison with the nanoparticle precipitates.   
     
     
         19 . The friction extrusion of  claim 18 , the nanoparticle precipitates having a density within a range of 10 22 /m 3  to 10 23 /m 3  dispersed in the bulk material. 
     
     
         20 . The friction extrusion of  claim 18 , wherein the friction extrusion is dimensionally stable under stress at a temperature of 650° C.