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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No. 63/410,556 filed on Sep. 27, 2022, the contents of which are herein incorporated by reference.

STATEMENT REGARDING RIGHTS TO INVENTION ADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

This invention was made with Government support under Contract DE-AC0576RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.

FIELD OF THE INVENTION

The present document relates generally to extrusion processing, extrusion tools, and resultant extrudates. More particularly, the present subject matter relates to a shear-assisted extrusion system and process for production of extrudates including high-performance composite extrudates.

BACKGROUND

Solid phase processing techniques such as friction consolidation and extrusion (FCE) and shear assisted processing and extrusion (ShAPE) of high melting point alloys use tooling made from materials that are very strong at high temperatures, such as tungsten rhenium hafnium carbide (“W-Re-HfC” herein), or another tungsten alloy tolerant of high temperatures (e.g., 2000K). A rod of W-Re-HfC is machined to form the desired tool (which can be referred to as a “die” herein) and held by a tool holder during use. These tooling materials are generally quite expensive. As an illustration, a representative cost of 1.25-inch diameter W-Re-HfC is approximately $2,000/inch for the material at the time of filing of this document, before machining costs. For example, raw materials for a 4-inch tool would cost approximately $8,000.

Certain tool holders use a set screw arrangement to hold the tool in place during solid phase processing, enabling transfer of the torque of a moving spindle to the tool and the material being processed. A relatively large portion of the tool, such as a shank, is inserted into the tool holder (or chuck), allowing engagement of the shank of the tool by screws through the holder to secure the tool to the holder. For example, a 4-inch tool would have approximately 2 inches inserted into the tool holder, contributing substantially to the raw material costs of the tool. Further, the set screw arrangement causes stress concentration during solid phase processing. Cracking and failure of the tool and tool holder can occur during use.

SUMMARY

ODS Alloys

Oxide dispersion strengthened (ODS) alloys exhibit high heat resistance, ductility, and strength, making these materials useful in various applications where high heat is a factor. For example, nuclear and fusion energy applications seek materials that maintain their performance under high temperature and stress in addition to radiation.

Certain approaches to processes of forming ODS steel through mechanical alloying are not viable for forming ODS alloys for nuclear and fusion energy applications. For example, ball milling an ODS precursor powder generates a resultant ODS alloy that is non-uniform and likely contaminated. Further, ball milling is too expensive and time consuming to be scaled for commercial applications.

Sponge Iron

Sponge iron is a relatively inexpensive form of iron that can be formed as an intermediate product from direct reduction ironmaking (DRI) processes. DRI processes can have lower carbon emissions as compared to blast furnace ironmaking. The intermediary sponge iron may not be useful on its own and is used as an iron feedstock. For example, in certain steel manufacturing processes, sponge iron can be melted down in an electric arc furnace (EAF) and purified for commercial use. Alloying elements can be added to the melted and purified sponge iron, including carbon to make steels.

That is, while the formation of the sponge iron is a solid phase process, certain uses of sponge iron to make alloys involve melting down the sponge iron. Melting metals is energy-intensive and contributes to carbon emissions. Further, adding greenhouse gas-emitting alloying elements, namely carbon, to the sponge iron further contributes to carbon emissions.

This document describes, among other things, examples of a tool assembly for friction extrusion that 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.

This Summary is intended to provide an overview of certain aspects of the present subject matter, which are further described in the below Detailed Description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1A illustrates a system for forming an extrudate, according to some examples.

FIG. 1B illustrates a tool for plasticizing material, according to some examples.

FIG. 2A illustrate an example of a tool in a side view.

FIG. 2B illustrates an example of a tool in a top-down view.

FIG. 2C illustrates an example of a tool in a bottom-up view.

FIG. 3A illustrates an example of a tool holder in a side view.

FIG. 3B illustrates an example of a tool holder in a bottom-up view.

FIG. 3C illustrates an example of a tool holder in a top-down view.

FIG. 4A illustrates an example of a tool assembly in an exploded view.

FIG. 4B illustrates an example of an interior tool assembly.

FIG. 4C illustrates an example of an exterior tool assembly.

FIG. 5 illustrates several an example of faceted cross-sectional profiles of a die.

FIG. 6 is a flowchart of an example of portions of a method of generating an extrudate.

FIG. 7 is a flowchart of an example of portions of a method of generating an extrudate.

FIG. 8 is a flowchart of an example of portions of a method of generating an extrudate.

FIG. 9A illustrates a section view of an example of portions of a system for applying rotational force and axial force to a feedstock.

FIG. 9B illustrates an example of grains of a feedstock.

FIG. 9C illustrates an example of grains of an extrudate.

FIG. 10 is an example of a comparison of fracture toughness of an ODS alloy extrudate and certain comparison materials.

FIG. 11 includes an example of compositional data from APT needles of a bulk material and nanoparticle precipitates.

DETAILED DESCRIPTION

Methods and tool assemblies are described herein for solid phase processing in general and friction extrusion in particular. Friction extrusion plasticizes one or more input materials to form an extruded material, called an “extrudate” herein. The extrudate is generally an alloy of the one or more input materials.

FIG. 1A illustrates an example of portions of a system 100 for forming an extrudate 102. The system 100 can include a tool 104 for applying force to a feedstock 106. The system 100 can use shear assisted processing and extrusion (ShAPE) technology, such as involving applying an axial compressing force and a rotating shearing force to deform the feedstock 106. The force(s) applied by the system 100 can cause plastic deformation of the feedstock 106 (e.g., “plasticize” the feedstock 106), which can also be referred to as permanent or non-reversible deformation.

For example, an axial force can be applied along a direction of a longitudinal central axis 108 of the system 100 such as to provide compression. The longitudinal central axis 108 can define a central axis along which the extrudate 102 extends axially and about which the tool 104 can rotate. An axial compressive force can be applied by moving the tool 104 at a travel speed (e.g., mm/minute) along the longitudinal central axis 108. The travel speed (and associated axial force) may vary during friction extrusion, for example, to maintain deformation of the feedstock 106. The linear motion of the tool 104 to deform the feedstock 106 can be referred to as upset.

Concurrently, a rotating force can be applied about the longitudinal central axis 108, such as to provide shearing. A rotating force can be applied by moving the tool 104 at a rotational speed (e.g., rotations/minute, “RPM”) about the longitudinal central axis 108. The rotation speed (and associated rotational force) may vary during friction extrusion. For example, the rotation speed can vary from 0 to approximately 2000 RPM. The rotating force can be continuous in a single direction. Additionally, or alternatively, the rotating force can oscillate in direction, for example, cyclically oscillating in direction.

The tool 104 can include a friction extrusion die. The tool 104 can include a distal face 110 that can define at least one topographical ridge or groove feature 112. The groove feature 112 can include one or more spirals that can direct plasticized material inward towards a central passageway 114 of the tool 104. The distal face 110 can include other surface morphologies or can be flat. The tool 104 can be formed of a metal, such as W-Re-HfC.

The feedstock 106 can include one or more materials to be plasticized. For example, the feedstock 106 can include one or more powdered materials. For example, the feedstock 106 can include or consist of ODS powder. The feedstock 106 can include one or more of beads, pellets, and/or flakes of material. For example, the feedstock 106 can include or consist of pellets formed from iron ore. The feedstock 106 can include a billet of material; the billet can consist of solid material, powdered material, or a combination thereof. The feedstock 106 can include material of any format to be plasticized, such as one or more of one or more billets, wires, rods, bars, tubes, or the like. The feedstock 106 may include one or more non-ferritic elements. The one or more non-ferritic elements can include impurities, such as those naturally found in raw forms of iron. In some examples, the one or more non-ferritic elements can be oxides, alloys, ceramics, or other compounds.

The feedstock 106 can be held, such as by a container 118. The container 118 can include a cylindrical cannister that can be open on one end and closed on a second end. The cross-sectional shape of the canister may vary. The container 118 can include an optional mandrel 120 that can be located about the center of the container 118.

The distal face 110 can be thrust against the feedstock 106 in the container 118 (or vice versa). An axial force and a rotating force can be applied to the tool 104 to plunge the distal face 110 into the feedstock 106. For example, the axial force and the rotational force can be applied to a proximal end of the tool 104 (or associated tool assembly) and a distal end of the tool 104 imparts these forces to the feedstock 106. Additionally, or alternatively, an axial force and a rotating force can be applied to the container 118 to provide a combination of shear and compressive forces to plasticize material.

In response to applying the axial force and the rotating force, the at least one topographical ridge or groove feature 112 induces plasticization of material at an interface 116 of the feedstock 106 with the distal face 110. The extrudate 102 is formed of the plasticized material extruded from the system 100. The central passageway 114 of the tool 104 can carry the extrudate 102 in a desired direction. For example, the central passageway 114 can carry the extrudate 102 along the longitudinal central axis 108 in a direction opposing the direction of the compressive axial force.

The extrudate 102 is formed of the solid phase processed feedstock 106. The extrudate 102 can be formed without melting the feedstock 106. The extrudate 102 can include a metal, an alloy, or a composite material. The extrudate 102 can have superior strength and hardness properties compared to the feedstock 106 or materials used to form the feedstock 106. The system 100 can harden and strengthen the materials in forming the extrudate 102.

FIG. 1B illustrates an example of portions of the tool 104 for plasticizing material. The tool 104 can include an optional extrusion aperture 122. The extrusion aperture 122 can include an opening to the central passageway 114 for carrying away the extrudate 102. For example, the extrusion aperture 122 can be located at or near the center of the distal face 110 that includes at least one topographical ridge or groove feature 112.

The extrudate 102 can be formed to take on the shape of the extrusion aperture 122 and the central passageway 114. As plasticized material is extruded by the tool 104 assembly, it can be confined by and can form to the shape of the central passageway 114. For example, a central passageway 114 and extrusion aperture 122 having a circular cross-section can form a rod-shaped extrudate 102 with the circular cross-section. An extrudate 102 with a desired cross-sectional shape can be formed by forming the central passageway 114 and extrusion aperture 122 to have the desired cross-sectional shape, e.g., rectangular, square, triangle, oblong, or more complex shapes, such as T-slot cross-sections.

The size and shape of the extrudate 102 can be further formed by the optional mandrel 120. When the container 118 is accompanied by the mandrel 120, the plasticized material can be extruded between the extrusion aperture 122 on the exterior and the mandrel 120 on the interior, forming an extrudate with a hollow cross-section. That is, the mandrel 120 can be used with the central passageway 114 to extrude a tube-shaped extrudate 102.

The tool 104 can be held in place during use by a tool holder 124. A proximal end of the tool 104 (not pictured in FIG. 1B) can be held by the tool holder 124. As shown in FIG. 1B, protruding from the tool holder 124 are a distal end 128 and, optionally, at least part of a medial section 126 of the tool 104.

FIG. 2A-FIG. 2C illustrate example of portions of the tool 202 in multiple views. The tool 202 can comprise an example of the tool 104. For example, the tool 202 can include a distal face 206, which can comprise an example of the distal face 110, and an extrusion aperture 204, which can comprise an example of the extrusion aperture 122. Further the tool 202 can include a spiral groove feature 208, which can comprise an example of the at least one topographic ridge or groove feature 112.

The tool 202 can further include a distal end 210, a proximal end 212 and a medial section 214. The medial section 214 connects the distal end 210 and the proximal end 212. The medial section 214 can have a larger diameter than either the distal end 210 or the proximal end 212, such as to define a shoulder. The shoulder defined by the medial section 214 can limit a depth of insertion of the proximal end 212 into a tool holder (e.g., tool holder 124). The shoulder can support in aligning the tool into the tool holder by keeping the tool 104 centered on the longitudinal central axis 218.

The distal end 210 is the end of the tool 202 configured to induce plasticization. The distal end 210 includes the distal face 206. The distal end 210 can be exterior to a tool holder when in use. For example, as depicted in FIG. 1B, the distal end 128 protrudes from the tool holder 124.

The proximal end 212 is the end of the tool 202 that can be configured to mate with a tool holder. The proximal end 212 can define a non-circular cross-sectional profile, such as a faceted cross-sectional profile 216 that can be configured to mate with a corresponding receiving end of a tool holder. The faceted cross-sectional profile 216 can be defined by an outer surface of the proximal end 212 of the tool 202. Further, the outer surface of the proximal end 212 of the tool 202 can define a protrusion with the faceted cross-sectional profile 216 (e.g., a male connector).

The faceted cross-sectional profile 216 can define a number of faces 220 on the proximal end 212 of the tool 202, the number of faces 220 being greater than or equal to two. The faces 220 can be referred to as “facets” of the faceted cross-sectional profile 216. Respective faces 220 are defined by vertices of the faceted cross-sectional profile 216. The number of faces 220 can be equal to the number of vertices defined by the faceted cross-sectional profile 216. When the proximal end 212 forms a protrusion, an angle between respective faces of the tool 202 can be >180°.

As depicted in FIG. 2B, the respective faces 220 defined by the faceted cross-sectional profile 216 can include portions that extend outward away from a longitudinal central axis 218, such as to help enable engagement by a tool holder of the respective faces 220. The longitudinal central axis 218 can comprise an example of the longitudinal central axis 108. The faces 220 can be located on the outer surface of the proximal end 212.

The faces 220 can be curved, such as to help provide engagement of a tool holder, such as is described further in relation to FIG. 3A-FIG. 3C. Each individual face 220 can be curved such that a longitudinal center of the face 220 is closest to the longitudinal central axis 218. The longitudinal edges of each face 220 (e.g., where a face 220 meets another face 220 along a longitudinal vertex) can extend furthest from the longitudinal central axis 218. Each face 220 can be concave.

Generally, the faceted cross-sectional profile 216 can be non-circular, such as polygonal or otherwise substantially polygonal. That is, while polygons have generally straight edges, a substantially polygonal shape can have modestly curved edges, and polygonal can refer to an arrangement of vertices of a cross-sectional shape that define a polygonal shape when connected to each other by lines. For example, as depicted in FIG. 2B, the faceted cross-sectional profile 216 is substantially hexagonal. In other words, the slightly curved face 220 defined by the faceted cross-sectional profile 216 can form an outline of the cross-sectional profile that can be substantially hexagonal. The faceted cross-sectional profile 216 in FIG. 2B can be recognized as hexagonal or substantially hexagonal. Other examples of polygonal faceted cross-sectional profiles are discussed in relation to FIG. 5. In some examples, the faceted cross-sectional profile 216 can be hypocycloidic in shape, or otherwise curved, such as define by a spline.

FIG. 3A-FIG. 3B illustrate an example of portions of a tool holder 302 in multiple views. The tool holder 302 can be configured to hold a tool, such as a friction extrusion die. For example, the tool holder 302 can be configured to hold the tool 202 of FIG. 2A-FIG. 2C. The tool holder 302 can comprise an example of the tool holder 124. The tool holder 302 can include a receiving end 304 and a stem 306.

The stem 306 can extend along a longitudinal central axis 308, parallel to a central passageway 310. The central passageway 310 can comprise an example of a continuation of the central passageway 114 of the tool 104. The central passageway 310 can carry extrudate away from the tool. The stem 306 can include a flat area 312 for screws to attach to, such as discussed in association with FIG. 4A-FIG. 4C. The central passageway 310 can be omitted in some examples; the central passageway 114 may terminate with the tool 104. For example, the extrudate 102 forms in the tool 104 and a short distance behind it (e.g., 65 mm). Inclusion of the central passageway 310 through the tool holder 302 enables formation of longer extrudates.

The receiving end 304 can be configured to receive at least part of a tool. The receiving end 304 can be configured to mate with at least the proximal end 212 of the tool 202. The receiving end 304 can define a socket 314 that can be configured to mate with the faceted cross-sectional profile 216 of the proximal end 212 of the tool 202. The socket 314 can be defined by a surface of the tool holder 302 extending inwards towards the center of the tool holder 302. The socket 314 can be defined about a longitudinal central axis 308. The longitudinal central axis 308 can be the longitudinal central axis 108.

The socket 314 can define an engagement section 316 and, optionally, a non-engagement section 318. The engagement section 316 can be configured to provide engagement with faces 220 defined by the faceted cross-sectional profile 216 of the tool 202. The non-engagement section 318 can refer to any remaining portion of the socket 314. The non-engagement section 318 can be configured to receive the medial section 214 of the tool 202. The engagement section 316 can be located deeper within the socket 314 than the non-engagement section 318. For example, the socket 314 in FIG. 3B depicts a non-engagement section 318 at the opening of the socket and an engagement section 316 at the base of the socket 314, where the non-engagement section 318 can be defined by a smooth circular cross-section that is not configured to engage with faces 220 of the tool 202.

The engagement section 316 of the tool holder 302 can include a faceted cross-sectional profile complementary to or congruent with the faceted cross-sectional profile 216 of the tool 202 for mating. The faceted cross-sectional profile 216 of the tool 202 can fit snugly within the engagement section 316 of the tool holder 302. The engagement section 316 can define faces 320 on an interior surface of the socket 314.

The faces 320 of the tool holder 302 can be curved to reduce stress concentration. The faces 320 can extend inward towards the longitudinal central axis 308, such as to help provide engagement by the tool holder 302 of respective faces 220 defined by the faceted cross-sectional profile 216 of the tool 202. Each individual face 320 can be curved, for example, to align with respective curved faces 220 for mating. Each face 320 can be convex.

Additionally, or alternatively, the faces 220 of the tool 202 are flat and the faces 320 of the tool holder 302 are curved (e.g., convex). In such examples, the curved faces 320 of the tool holder 302 can spread out stress concentration. Additionally, or alternatively, the faces 220 of the tool 202 are curved (e.g., concave) and the faces 320 of the tool holder 302 are flat. In such examples, the curved faces 220 of the tool 202 can spread out stress concentration.

For example, a proximal end 212 of the tool 202 can be inserted into the receiving end 304 of the tool holder 302. When inserted, each individual face 220 of the proximal end 212 of the tool 202 can abut a respective face 320 of the receiving end 304 of the tool holder 302, such as to mate the tool 202 and the tool holder 302. The mating enables the transfer of torque from the tool holder 302 to the tool 202 (and vice versa), such that when the axial force and the rotational force are applied, the abutted faces engage one another.

The curved faces 220 abutting the curved faces 320 shifts the stress concentration away from the vertices in the socket 314 and towards the center of the faces 220, 320. Because the stress is not concentrated at the vertices, the mating of the tool 202 and tool holder 302 can withstand greater stress before deforming the tool 202 (e.g., as compared to a non-curved face example). For example, a perfectly hexagonal faceted cross-sectional profile 216 would begin deforming such that the vertices of the facets are rounded off by the edges of the socket 314, similar to stripping a screw head under too much torque.

Further, the tool 202 and tool holder 302 can mate without screws, unlike certain other tool holders. As a result, the tool 202 and tool holder 302 are less prone to cracking and failure during use than certain other screw-based tool holders. Further, the tool 202 can be made from a smaller length of W-Re-HfC if screws are not used, substantially reducing the raw material costs of forming a friction extrusion die.

The tool 202 has a socket 314 and the tool holder 302 can include a protruding proximal end 212, if desired. In other words, the male connector of the tool 202 and female connector of the tool holder 302 can be inverted.

FIG. 4A-FIG. 4C illustrate an example of portions of a tool assembly 400 in multiple views. The tool assembly 400 can include a tool holder 402, which can comprise an example of the tool holder 124 or the tool holder 302 previously discussed. The tool assembly 400 can further include a housing 404, a fitting 406, an inner cooling tube 408 and an outer cooling tube 410. The tool assembly 400 can provide water cooling to the tool holder 302.

The inner cooling tube 408 can provide water (e.g., chilled water) to a proximal end of the tool holder 402. The inner cooling tube 408 can provide the ‘input’ water to cool the tool holder 402. The chilled water cools the hot tool holder 402 such that the water absorbs heat and becomes heated water. The outer cooling tube 410 can carry away water (e.g., heated water) from the tool holder 402. The outer cooling tube 410 can accommodate the ‘output’ water being flushed out. The outer cooling tube 410 can carry the heated water back to a chiller (e.g., a cooling chamber), where it is cooled and reused to cool the tool holder 402.

The inner cooling tube 408 can fit within the outer cooling tube 410, forming a cooling tube. The inner cooling tube 408 can be inserted within the tool holder 402 (e.g., through the stem 306). The inner cooling tube 408 can be inserted into a cavity that is different from but substantially parallel to the central passageway 310. The extrudate does not pass through the cooling tube. The fitting 406 can connect the outer cooling tube 410 to the tool holder 402. The fitting 406 can provide a seal between the outer cooling tube 410 and the tool holder 402. The fitting 406 can also provide a seal between the inner cooling tube 408 and the tool holder 402.

The housing 404 can fit over the assembly comprising the inner cooling tube 408, the outer cooling tube 410 and the fitting 406. The housing 404 can fit over the stem 306 of the tool holder 402 and can attach via screws to a flat area 312 of the stem 306. The housing 404 can leave the receiving end 304 of the tool holder 402 exposed for receiving a proximal end 212 of a tool 202.

FIG. 5 illustrates several examples of faceted cross-sectional profiles of a tool, such as tool 202, where “n” is a positive integer greater than two. For example, a tool can have a substantially pentagonal faceted cross-sectional profile 502, a substantially triangular faceted cross-sectional profile 504, a substantially octagonal faceted cross-sectional profile 506, or, generally, a substantially “n”-sided faceted cross-sectional profile 508.

Each example of a faceted cross-sectional profile can define a number of curved faces. For example, the n-sided faceted cross-sectional profile 508 has n curved faces. Each example of a faceted cross-sectional profile of a tool can be configured to mate with a tool holder having a congruent faceted cross-sectional profile. For example, a protruding proximal end having a pentagonal faceted cross-sectional profile 502 can be configured to mate with a socket having a pentagonal faceted cross-sectional profile.

FIG. 6 is an example of a flowchart of portions of a method 600 of generating an extrudate. The method 600 can be carried out using a system for friction extrusion, such as the system 100. The method 600 can be carried out using a tool and tool holder configured to mate, such as tool 202 and tool holder 302, or any various examples discussed in association with the figures herein. One or more features of these one or more examples may be combined to form other examples.

At block 602, the method 600 can include receiving an iron feedstock including one or more non-ferritic elements. The iron feedstock can comprise an example of the feedstock 106, such as powder, flakes, or billets. The one or more non-ferritic elements can include any impurity such as can be commonly found in an iron feedstock. According to some examples, the iron feedstock is an ODS powder, and the one or more non-ferritic elements can include yttrium, titanium, and oxygen, as discussed further in association with FIG. 7. According to some examples, the iron feedstock is a sponge iron, and the one or more non-ferritic elements are impurities that can include silica and alumina, as discussed further in association with FIG. 8.

At block 604, the method 600 can include 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. The axial force and the rotational force can be applied by a friction extrusion system, such as the system 100. The pressure generated by die imparting the axial force and the rotational force on the iron feedstock induce high stresses that cause the iron feedstock to undergo plastic deformation (e.g., “plasticize”). The plasticized material reforms (e.g., recrystallizes) as it is extruded from the die into the iron alloy extrudate having a different microstructure than the iron feedstock. That is, the iron alloy extrudate forms in situ from the plasticized material.

The microstructures of the iron alloy extrudates generated can have superior strength properties as a result of the method 600, such as discussed further in association with FIG. 9A-FIG. 9C. This method 600 can produce iron alloys with better strength, ductility, and corrosion resistance at the macroscopic level together with increased and better performance. This method 600 can help reduce or eliminate the need for additional heating. That is, the heat generated from the friction of the die imparting the axial and rotational forces on the iron feedstock is sufficient to process the iron feedstock above its recrystallization temperature without requiring additional heating.

The die can include a friction extrusion die, such as tool 202 or any other example of the tools described herein. For example, the die can include a 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. Further, the die can include 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.

FIG. 7 is an example of a flowchart of portions of a method 700 of generating an extrudate. The method 700 can comprise an example of the method 600. The method 700 can be used to generate an iron alloy extrudate that is an ODS steel extrudate. According to some examples, block 702 through block 706 comprise a process of gas atomization reaction synthesis (GARS) for forming ODS alloy precursor.

At block 702, the method 700 can include liquifying material comprising iron. The liquified material can further comprise chromium, titanium, and yttrium. For example, the material can be an iron alloy comprising chromium, titanium, and yttrium. Additionally, or alternatively, the iron can be any iron, such as iron ore or other unprocessed forms of iron, which may include other non-ferritic elements. The material can be liquified by heating, if desired, for example, in a crucible. Additionally, or alternatively, high pressure may liquify the material. According to some examples, the material comprising iron can be superheated.

At block 704, the method 700 can include forming liquid droplets. The forming of liquid droplets can be referred to as ‘atomization.’ The liquid iron can be forced through a nozzle such as to form a stream of droplets. The nozzle can include a predetermined pour tube geometry and one or more nozzle jets to produce a desired flow rate of liquid droplets.

At block 706, the method 700 can include applying a gas (e.g., at a specified pressure) comprising oxygen to the liquid droplets for form an iron feedstock. The gas can be an inert gas, such as argon or another noble gas. The gas can be applied by one or more nozzles aimed to intercept the stream of droplets of liquid iron. The pressure of the gas being applied is specified to intercept the stream of droplets of liquid iron and reduce by a reduction reaction. For example, the specified pressure can generate a fast-moving stream of gas.

As the liquid iron is expelled from the nozzle, the gas comprising oxygen can cause an in situ oxidization reaction. The gas can rapidly cool the liquid iron droplets into a solid while forming an oxidized layer on the surface. The cooled oxidized droplets are an iron feedstock that can be termed an ODS alloy precursor powder.

At block 602 and block 604, the method 700 can include using the ODS alloy precursor as an iron feedstock to generate an iron alloy extrudate that is an ODS alloy. The ODS alloy can include a bulk material and nanoparticle precipitates dispersed in the bulk material. In some examples, the nanoparticle precipitates can have a density within a range of 10²²/m³ to 10²³/m³ dispersed in the bulk material. The nanoparticle precipitates can have a relatively higher atomic percentages of non-ferritic elements, such as titanium, oxygen, and yttrium, such as in comparison with the bulk material. Conversely, the bulk material can have a relatively higher atomic percentage of iron than the nanoparticle precipitates. According to some examples, the ODS iron alloy can have a fracture toughness exceeding 250 MPa·m^1/2 at room temperature.

The resultant ODS alloy extrudate can be potentially viable for nuclear and fusion energy applications. For example, unlike certain ODS alloys generated using ball milling, the present ODS alloy extrudate can have a uniform microstructure. The microstructure of the ODS alloy is discussed in greater detail in association with FIG. 11. The method 700 can be less expensive and less time consuming than the conventional ball-milling processes. As a result, the method 700 can be more commercially viable than certain other processes.

FIG. 8 is a flowchart of an example of portions of a method 800 of generating an extrudate. The method 800 can comprise an example of the method 600. The method 800 can be used to generate an iron alloy extrudate such as a sponge iron extrudate. For example, block 802 through block 808 can comprise a process of forming a sponge iron feedstock from iron ore.

At block 802, the method 800 can include receiving iron ore comprising silica and alumina impurities. The iron ore comprises one or more non-ferritic elements in the silica and alumina impurities. The iron ore can be an unprocessed raw material. The iron ore can comprise any composition of silica and alumina impurities.

At block 804, the method 800 can include grinding the iron ore into pieces of iron ore. The pieces of iron ore can be approximately gravel-sized or smaller, according to some examples.

At block 806, the method 800 can include purifying the pieces of iron ore to remove most silica and alumina. The purification can include one or more processes for removing silica and/or alumina. For example, the purification can include reducing by reduction reaction (e.g., direct reduction processes). The purification process may leave some silica and alumina, such as on the order of 5-30 weight percent of oxides. According to some examples, the oxide concentration is closer to 8-10 weight percent.

At block 808, the method 800 can include agglomerating the pieces into pellets to form an iron feedstock. According to some examples, the iron pellets can be at least 70 weight percent iron. The iron pellets can be a sponge iron feedstock.

At block 602 and block 604, the method 800 can include using the iron pellets, such as an iron feedstock, such as to generate an iron alloy extrudate that is a sponge iron extrudate. The method 800 can make use of the silica and alumina remaining in the iron pellets. During the plasticization and extrusion, the non-ferritic silica and alumina can be broken down and re-dissolved in the metal matrix, forming a metal matrix composite. The non-ferritic silica and alumina can provide reinforcement that can strengthen and harden the resultant crystalline structure. According to some examples, the extrudate is a high strength sponge iron having a yield strength within a range of 40 to 50 kilo-pounds per square inch (ksi) at room temperature and having a hardness within a range of 300 to 400 Vickers Pyramid Number (HV).

The method 800 can directly make iron alloys using sponge iron without requiring adding a greenhouse gas emitting ingredient, namely carbon and its associated products. Moreover, the method 800 can help eliminate the energy-intensive melting step in steelmaking. In other words, the method 800 can help provide an alternative, lower-emission process of using sponge iron.

FIG. 9A illustrates an example of a section view of portions of a system 900 for applying rotational force 902 and axial force 904 to a feedstock 906. The system 900 can comprise an example of the system 100. The system 900 can include a tool 908, which can comprise an example of the tool 104 or tool 202.

The feedstock 906 can be held in place, such as by a ring 910, which can also be referred to as a container, on a backing block 912. The ring 910 can be formed of a nickel-chromium-based superalloy such as Inconel® and the backing block 912 can be formed of a nickel alloy, or a refractory alloy.

The system 900 can include a thermocouple 914, such as for monitoring temperature at or near an interface between the tool 908 and feedstock 906. For example, the thermocouple 914 can be inserted in a slot in the tool 908 from the side. The slot can be, for example, located one millimeter above the interface. The thermocouple 914 can be used to monitor and adjust the temperature in order to change the microstructure of the extrudate. For example, responsive to determining the temperature is below a recrystallization temperature of an alloy being extruded, the system 900 can increase a travel speed and/or a rotating speed of the tool 908.

When the rotational force 902 and the axial force 904 are applied to the tool 908, the feedstock 906 is plasticized, changing its microstructure. FIG. 9B shows an example of a microstructure of the feedstock 906 before plasticization. FIG. 9C shows an example of a microstructure of a resultant extrudate.

FIG. 9B illustrates an example of grains of the feedstock 906. The illustration is generated from empirical electron backscatter diffraction (EBSD) of an ODS precursor at 30 micrometers (“microns”). At 30 microns, the empty space between each powder of ODS precursor can be resolved, in this example. The average grain size of the feedstock 906 is 7.7 microns.

FIG. 9C illustrates an example of grains of an extrudate that can be generated by the system 900. The illustration is generated from empirical EBSD of an ODS alloy extrudate generated by the method 700. As a result of the extrusion, the average grain size can be reduced to 2.4 microns. The plasticization induced by the rotational force 902 and the axial force 904 has broken down the larger grains of FIG. 9B, which recrystallized as the smaller grains of FIG. 9C.

The comprehensive resizing of the grains during extrusion indicates the feedstock 906 is fully processed (e.g., plasticized) by the friction extrusion. This enables generating ODS alloy extrudates with uniform microstructures, such as desirable for commercial use. Other approaches, such as balled-milled ODS alloys that are conventionally extruded, can have non-uniform microstructures, which are prone to cracking and failure.

FIG. 10 is an example of a comparison of fracture toughness of an ODS alloy extrudate and certain comparison materials. An empirical data 1002 can be compared to a plot 1004 including comparison materials 1006. Samples of ODS alloy extrudates can be formed by methods 700 were tested to measure the empirical data 1002. The comparison materials 1006 include other ODS steels that have been formed in conventional ways including ball milling and normal forming processes such as extrusion, including steels that have been hot worked and cold worked.

As can be compared, the fracture toughness of the ODS alloy extrudates 1002 greatly exceed the comparison materials 1006 at room temperature. The ODS alloy extrudates 1002 have fracture toughness exceeding 250 MPa·m^1/2 at room temperature, according to some examples. The ODS alloy extrudates 1002 have fracture toughness exceeding 400 MPa·m^1/2 in some examples. The comparison materials 1006 have a maximum fracture toughness of approximately 270 MPa·m^1/2 at room temperature. In other words, the ODS alloys generated using method 700 outperform the comparison materials 1006.

FIG. 11 includes an example of compositional data from APT needles of a bulk material 1102 and nanoparticle precipitates 1104. The APT needles were taken from samples of ODS alloy extrudates generated by method 700. The nanoparticle precipitates 1104 are dispersed in the bulk material 1102. According to some examples, the nanoparticle precipitates 1104 have a density within a range of 10²²/m³ to 10²³/m³ dispersed in the bulk material. The nanoparticle precipitates 1104 may also be referred to as nano-oxides.

The bulk material 1102 is associated with empirical bulk composition data 1106 and the nanoparticle precipitates 1104 are associated with empirical precipitate composition data 1108. The bulk material 1102 has a relatively higher atomic percentage of iron than the nanoparticle precipitates. The nanoparticle precipitates 1104 have a relatively higher atomic percentage of non-ferritic elements than the bulk material 1102. The non-ferritic elements can include at least one of titanium, oxygen, yttrium, chromium, or other non-ferritic elements.

The ODS alloy extrudates generated by method 700 are dimensionally stable under stress at a temperature of 650° C. For example, ongoing creep testing at the time of this filing indicate the ODS alloy extrudates having creep properties that are superior to reduced activation ferritic martensitic (RAFM) steels and castable nanostructured alloys (CNAs). The ongoing creep testing indicates the ODS alloy extrudates have creep properties comparable to the ODS Eurofer® steel alloys, being able to withstand the load for approximately 100 hours at 650° C., having a creep rupture stress of approximately 150 MPa. The ongoing creep testing indicates these ODS alloy extrudates have a crystalline structure that is dimensionally stable and resistant to deformations induced by creep at temperatures greater than or equal to 650° C.

The ODS ally extrudates that are dimensionally stable at 650° C. are better suited for nuclear and fusion applications than comparison materials. For example, RAFM steels are limited to operating at or below 550° C. Further, the method 700 is expected to reduce costs by at least a factor of 2 when compared to comparison materials (e.g., RAFM).

To better illustrate the inductor structures and formation or fabrication techniques described herein, a non-limiting set of Example embodiments are set forth below as numerically identified Examples.

Example 1 is 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.

Example 2 is the tool assembly of example 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.

Example 3 is the tool assembly of example 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.

Example 4 is the tool assembly of example 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.

Example 5 is the tool assembly of example 1, wherein the faceted cross-sectional profile is polygonal.

Example 6 is the tool assembly of example 1, wherein the faceted cross-sectional profile is defined by an outer surface of the proximal end of the friction extrusion die.

Example 7 is the tool assembly of example 6, wherein the outer surface of the proximal end of the friction extrusion die defines a protrusion with the faceted cross-sectional profile.

Example 8 is 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.

Example 9 is the method of example 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.

Example 10 is the method of example 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.

Example 11 is the method of example 10, wherein the one or more non-ferritic elements comprise at least one of yttrium, titanium, or oxygen.

Example 12 is the method of example 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 10²²/m³ to 10²³/m³ dispersed in the bulk material, and wherein the bulk material has a relatively higher atomic percentage of iron than the nanoparticle precipitates.

Example 13 is the method of example 12, the ODS iron alloy having a fracture toughness exceeding 250 megapascals by square root meter (MPa·m^1/2) at room temperature.

Example 14 is the method of example 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.

Example 15 is the method of example 14, wherein the one or more non-ferritic elements comprise at least one of silica or alumina.

Example 16 is the method of example 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.

Example 17 is the method of example 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).

Example 18 is 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.

Example 19 is the friction extrusion of example 18, the nanoparticle precipitates having a density within a range of 10²²/m³ to 10²³/m³ dispersed in the bulk material.

Example 20 is the friction extrusion of example 18, wherein the friction extrusion is dimensionally stable under stress at a temperature of 650° C.

Example 21 is an apparatus comprising means to implement of any of Examples 1-20.

Example 22 is a system to implement of any of Examples 1-20.

Example 23 is a method to implement of any of Examples 1-11 or Example 20.

Each of these non-limiting examples can stand on its own or can be combined in various permutations or combinations with one or more of the other examples.

The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventor also contemplates examples in which only those elements shown or described are provided. Moreover, the present inventor also contemplates examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” can include “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

The method examples described herein may be machine or computer-implemented at least in part. Some examples may include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device or system to perform methods as described in the above examples. An implementation of such methods may include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code may include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, the code may be tangibly stored on one or more volatile or non-volatile computer-readable media during execution or at other times.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) can be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features can be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter can lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

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 1022/m3 to 1023/m3 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·m1/2) 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·m1/2) 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 1022/m3 to 1023/m3 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.