CN112512710B - Method for forming hollow profile non-circular extrusions using shear-assisted machining and extrusion - Google Patents

Abstract

A process for forming an extruded product is disclosed using an apparatus having a vortex face configured to apply rotational shear force and axial extrusion force to the same preselected location on a material, wherein a combination of the rotational shear force and axial extrusion force at the same location results in plasticization, flow and recombination of a portion of the material in a desired configuration. This process provides a number of advantages and industrial applications (including but not limited to extruded tubes for vehicle components), with 50% to 100% greater ductility and energy absorption than conventional extrusion techniques, while significantly reducing manufacturing costs.

Description

Method for forming hollow profile non-circular extrusions using shear-assisted machining and extrusion

Cross Reference to Related Applications

The present application claims priority from U.S. patent application serial No. 16/028,173 filed on 7.5.2018 (which is a continuation of part of U.S. patent application serial No. 15/898,515 filed on 2.17.2018 (which claims the benefit of U.S. provisional application serial No. 62/460,227 filed on 2.17.2017)). U.S. patent application Ser. No. 16/028,173 is also a continuation of and claims priority to part of U.S. patent application Ser. No. 15/351,201, filed 11/14 in 2016 (which claims the benefit of U.S. provisional application Ser. No. 62/313,500 filed 3/25 in 2016). U.S. patent application Ser. No. 16/028,173 is also a continuation of and claims priority from part of U.S. patent application Ser. No. 14/222,468 filed on day 21 3 of 2014 (which claims benefit from U.S. provisional application Ser. No. 61/804,560 filed on day 22 of 2013), all of which are incorporated herein by reference.

Statement regarding rights to the application under federally sponsored development

The application was completed with government support under contract DE-AC0576RL01830 awarded by the United states department of energy. The government has certain rights in this application.

Background

The increasing demand for fuel efficiency in transportation coupled with the ever-increasing demand for safety and compliance has led to a focus on the development and utilization of new materials and processes. In many cases, the barrier to entry into these areas is due to the lack of effective and efficient manufacturing methods. For example, the ability to replace steel automotive parts with materials made of magnesium or aluminum or their associated alloys is of great interest. Additionally, the ability to form hollow parts having strength equal to or greater than solid parts is an additional desirable objective. Previous attempts have failed or suffer from limitations based on various factors including lack of suitable manufacturing processes, expense of using rare earths in the alloy to impart desired properties, and high energy costs of production.

What is needed is a process and apparatus that is capable of producing such components of hollow cross section, made of rare earth-containing or non-rare earth-containing materials such as magnesium or aluminum, in an automobile or aerospace vehicle. What is also needed is a process and system for producing such articles that is more energy efficient, can be implemented more simply, and produces materials having the desired grain size, structure, and arrangement to maintain strength and provide adequate corrosion resistance. There is also a need for a simplified process that can form such structures directly from a blank, powder or sheet material without requiring additional processing steps. There is also a need for a simplified new method for forming high entropy alloy materials that is simpler and more efficient than current processes. The present disclosure provides a description of significant advances in meeting these needs.

Over the past few years, researchers in the national laboratory of North Pacific ocean have developed a novel shear assisted machining and extrusion (Shear Assisted Processing and Extrusion, shrape) technique that uses rotary stampings or dies rather than the simple axial feed stampings or dies used in conventional extrusion processes. As described hereinafter and in the previously cited, referenced and incorporated patent applications, this process and its associated apparatus provide a number of significant advantages, including reduced power consumption, better results, and a new set of "solid phase" type forming processes and machines. The deployment of the advantages of these processes and devices is contemplated in a variety of industries and applications including, but not limited to, transportation, projectile, high temperature applications, structural applications, nuclear applications, and corrosion resistant applications.

Various additional advantages and novel features of the application are described herein, and will become more readily apparent to those skilled in the art from, the following detailed description. In the foregoing and following description, only the preferred embodiment of the application has been shown and described, with reference to the best mode contemplated for carrying out the application. It will be appreciated that the application is capable of modification in various respects, all without departing from the application. Accordingly, the drawings and descriptions of the preferred embodiments set forth below are to be regarded as illustrative in nature, and not as restrictive.

Disclosure of Invention

The present specification provides examples of shear-assisted extrusion processes for forming non-circular hollow profile extrusions of desired composition from feedstock materials. This is achieved at a high level by using a scroll face having a plurality of grooves defined therein to apply rotational shear force and axial compressive force simultaneously to the same location on the feedstock material. The grooves are configured to direct plasticized material from a first position (typically at an interface between the material and the scroll face) to a second position (typically on a mold support surface) through an inlet defined in the scroll face. At this point, the separate streams of plasticized material are recombined and reconfigured into the desired shape having the preselected characteristics.

In some applications, the scroll face has a plurality of inlets, each inlet configured to direct plasticized material through the scroll face and to be recombined, either uniformly or separately, at a desired location. In the particular application described, the scroll face has two sets of grooves, one set for guiding material in from the outside and the other set configured to guide material out from the inside. In some cases, a third set of grooves surrounds the scroll face to contain material and prevent flash.

Such a process provides many advantages including the ability to form materials with better strength and corrosion resistance properties at lower temperatures, with lower forces, and with much lower energy strengths than are required by other processes.

For example, extrusion of the plasticized material is performed at a die face temperature of less than 150 ℃. In other cases, the axial pressing force is equal to or lower than 50MPa. In a specific example, magnesium alloy in the form of a billet is extruded into a desired form in an arrangement in which the axial extrusion force is equal to or lower than 25Mpa and the temperature is lower than 100 ℃. While these examples are provided for illustrative reasons, it should be clearly understood that the present description also contemplates various alternative configurations and alternative embodiments.

Another advantage of the presently disclosed embodiments is the ability to produce high quality extruded materials from a variety of raw materials, including billets, flakes, powders, and the like, without the need for additional pre-or post-treatments to achieve the desired results. In addition to this process, the present specification also provides an exemplary description of an apparatus for performing shear-assisted extrusion. In one configuration, the device has a swirling surface configured to apply a rotational shear force and an axial compressive force to the same preselected location on the material, wherein a combination of the rotational shear force and the axial compressive force at the same location results in plasticization of a portion of the material. The scroll face also has at least one recess and an inlet defined in the scroll face. The groove is configured to direct a flow of plasticized material from a first position (typically on a face of the vortex) through the inlet to a second position (typically on a back side of the vortex and at a location along the mandrel having a die bearing surface). Wherein the plasticized material recombines after passing through the vortex faces to form an extruded material having preselected characteristics at or near these second locations.

Such a process offers a number of advantages and industrial applications. For example, this technique is capable of extruding wires, rods and tubes for vehicle components with 50% to 100% greater ductility and energy absorption than conventional extrusion techniques, while significantly reducing manufacturing costs. This is done on smaller, cheaper machines than those used in conventional extrusion equipment. In addition, this process produces extrusions from lightweight materials (such as magnesium and aluminum alloys) with improved mechanical properties that are not achievable using conventional extrusion, and only requires direct production from powders, flakes or billets in a single step, which greatly reduces overall energy consumption and process time compared to conventional extrusion.

The application of the present method and apparatus may be used, for example, to form parts of the front end of an automobile, where it is expected that 30% weight savings may be achieved by replacing aluminum components with lighter weight magnesium, and 75% weight savings may be achieved by replacing steel with magnesium. Typically, processing into such embodiments requires the use of rare earth elements in the magnesium alloy. However, these rare earth elements are expensive and rare, and in many cases are found in environmentally difficult areas. Magnesium extrusions are too expensive for all vehicles except the most exotic ones. Thus, less than 1% of the weight of a typical passenger car comes from magnesium. However, the processes and apparatus described below enable the use of non-rare earth magnesium alloys to achieve results comparable to those using rare earth materials. In addition to a ten-fold reduction in power consumption (due to the much less force required to produce the extrusion) and smaller machine footprint requirements, this also results in additional cost savings.

Thus, the present technique can be easily applied to manufacturing lightweight magnesium parts of automobiles, such as front bumper beams and crush cans. In addition to automobiles, the deployment of the present application may promote further innovation and development in various industries such as aerospace, power industry, semiconductors, and the like. For example, this technique can be used to produce creep resistant steels for heat exchangers in the power industry, as well as advanced magnets and highly conductive copper for electrical machines. It is also used to produce high strength aluminium bars for the aerospace industry, where the aluminium bars are extruded directly from powder in one single step, with twice the ductility compared to conventional extrusion. In addition, the solid state cooling industry is researching the use of these methods to produce semiconductor thermoelectric materials.

The method of the present application allows for precise control of various features such as grain size and crystallographic orientation, which determine the mechanical properties (e.g., strength, ductility, and energy absorption) of the extrusion. This technique produces grain sizes of magnesium and aluminum alloys in the ultra-fine range (< 1 micron), which represents a 10 to 100 fold reduction compared to the starting material. In magnesium, the crystal orientation may be aligned off the extrusion direction, which is why the material has such a high energy absorption. A 45 degree offset has been achieved, which is ideal for maximizing energy absorption in magnesium alloys. By adjusting the geometry of the spiral grooves, the rotational speed of the mold, the amount of frictional heat generated at the material-mold interface, and the amount of force used to push the material through the mold, control of grain refinement and crystal orientation is obtained.

In addition, such extrusion processes allow for industrial scale production of materials with tailored structural properties. Unlike severe plastic deformation techniques that can only be produced on a laboratory scale, shAPE can scale according to industrial productivity, length, and geometry. In addition to controlling grain size, another layer of microstructure control has been demonstrated, where grain size and texture can be tuned by the wall thickness of the tubing—this is important, as mechanical properties can now be optimized for extrusion depending on whether the end application is subjected to stretching, compression or hydrostatic pressure. This may allow the automotive component to better resist failure during a collision while using less material.

The process combines linear and rotational shear resulting in a 10 to 50 fold reduction in extrusion force compared to conventional extrusion. This means that the size of the hydraulic ram, support members, mechanical structure and overall footprint can be significantly reduced compared to conventional extrusion equipment-thus enabling much smaller production machinery, lower capital expenditure and operating costs. This process generates all of the heat required to produce the extrusion by friction at the interface between the system blank and the scroll face die, thus eliminating the need for preheating and external heating used by other methods. This results in a greatly reduced power consumption; for example, producing a 2 inch diameter magnesium tube requires 11kW of power as much as operating a household kitchen oven-a 10 to 20 fold reduction in power consumption compared to conventional extrusion. The magnesium alloy with the described method exhibits extrusion ratios of up to 200:1 compared to 50:1 for conventional extrusion, which means that less or no material repetition through the machine is required to obtain the final extrusion diameter-resulting in lower production costs compared to conventional extrusion.

Finally, the study showed a 10-fold reduction in corrosion rate for extruded non-rare earth ZK60 magnesium performed under this process compared to conventional extruded ZK 60. This is due to the highly refined grain size and the ability to decompose, uniformly distribute (even dissolve) the second phase particles, which typically act as corrosion initiation sites. The process is also used to clad magnesium extrusions with an aluminum coating to reduce corrosion.

Various advantages and novel features of the disclosure are described herein, and will become more fully apparent to those having ordinary skill in the art from the following detailed description. In the foregoing and following description, exemplary embodiments of the disclosure are provided by way of illustration of the best mode contemplated for carrying out the disclosure. It will be appreciated that the present disclosure is capable of modification in various respects, without departing from the present disclosure. Accordingly, the drawings and descriptions of the preferred embodiments set forth below are to be regarded as illustrative in nature, and not as restrictive.

Drawings

Figure 1a shows a ShAPE arrangement for extruding a hollow section.

Fig. 1b shows another configuration for extruding a hollow section.

Fig. 2a shows a top perspective view of an improved scroll face tool for an inlet bridge mold.

Fig. 2b shows a bottom perspective view of a modified scroll face operating like an inlet bridge mold.

Fig. 2c shows a side view of the improved portal bridge mold.

Fig. 3 shows a schematic view of the apparatus and process for material separation shown in fig. 1-2.

Fig. 4a shows a ShAPE setup for consolidating a high entropy alloy (high entropy alloy, HEA) from an arc melting disc (puck) into a dense disc.

Fig. 4b shows an example of the swirl face of the rotary tool of fig. 4 a.

Fig. 4c shows an example where the HEA arc melted sample is crushed and placed within the chamber of the ShAPE device prior to processing.

Fig. 5 shows BSE-SEM images of cross-sections of HEA arc melt samples prior to ShAPE treatment, showing porosity, intermetallic phases and nucleated dendrite microstructure.

Fig. 6a shows a BSE-SEM image at the bottom of the disk resulting from the processing of the material in fig. 4 c.

Fig. 6b shows a BSE-SEM image of the middle of the disc.

Fig. 6c shows a BSE-SEM image of the interface between the high shear region and the non-uniform region (about 0.3mm from the disk surface).

Fig. 6d shows a BSE-SEM image of the high shear region.

Detailed Description

The following description, including the accompanying drawings, provides various examples of the application. It will be clear from the description of the application that the application is not limited to the embodiments shown in the drawings, but that the application also includes various modifications and embodiments thereof. The description is thus to be regarded as illustrative instead of limiting. While the application is susceptible to various modifications and alternative constructions, it is to be understood that the application is not intended to be limited to the specific forms disclosed, but, on the contrary, the application is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the application as defined in the claims.

In the previously described and related applications, various methods and techniques are described, wherein the described techniques and apparatus (referred to as ShAPE) are shown to provide a number of significant advantages, including the ability to control microstructures (such as crystal texture) through cross-sectional thickness, while also providing the ability to perform various other tasks. In this specification, we provide information about the use of the ShAPE technique to form materials having non-circular hollow profiles, as well as methods for making high entropy alloys that are useful in a variety of applications (e.g., projectiles). Exemplary applications are discussed in more detail below.

Referring now first to fig. 1a and 1b, examples of ShAPE devices and arrangements are provided. In an arrangement such as that of fig. 1, the rotary die 10 is pushed into the material 20 under certain conditions whereby the rotational and shear forces of the die face 12 and the die plunger 16 combine to plasticize the material 20 at the interface of the die face 12 and the material 20 and cause the plasticized material to flow in a desired direction. (in other embodiments, the material 20 may be rotated and the mold 10 pushed axially into the material 20 to provide such a combination of forces at the material face). In either case, the combination of axial and rotational forces plasticizes the material 20 at the interface with the mold face 12. The flow of plasticized material may then be directed to another location where a preselected length of the mold-bearing surface 24 facilitates the recombination of the plasticized material into an arrangement in which new and better grain size and texture control may be made at a microscopic level. This is then converted into an extruded product 22 having the desired properties. This process achieves better strength and corrosion resistance, as well as higher and better performance on a macroscopic level. This process eliminates the need for additional heating and curing and enables the process to function with various forms of materials including billets, powders or flakes without requiring extensive preparation processes (such as "steel canning"). This arrangement also provides methods for performing other steps, such as cladding, enhanced control of through wall thickness and other characteristics.

This arrangement differs from the prior art methods for extrusion and provides a number of advantages over the prior art methods for extrusion. First, during the extrusion process, the force peaks at the beginning and then drops once extrusion begins. This is known as breakthrough progress. In this ShAPE process, the temperature at the breakthrough point of progress is very low. For example, for magnesium tubing, the temperature at breakthrough development for ZK60 tubing with an OD of 2 "and a wall thickness of 75 mils is less than < 150 ℃. This lower temperature breakthrough progress is believed to be responsible in part for the superior construction and performance of the resulting extruded product.

Another feature is a low extrusion coefficient kf, which describes the extrusion resistance (i.e. a lower kf means a lower extrusion force/pressure). Kf was calculated to be 2.55MPa and 2.43MPa for extrusions (2 "OD, 75mil wall thickness) made of ZK60-T5 bars and ZK60 castings, respectively. The impact force and kf are very low compared to conventional extruded magnesium, with kf between 68.9 and 137.9 MPa. Thus, the ShAPE process achieves 20 to 50 times the kf (and hence the ram pressure) as compared to conventional extrusion. This not only contributes to the properties of the resulting material, but also reduces the energy consumption required for manufacturing. For example, in this process, the electrical power required to extrude ZK60-T5 bars and ZK60 castings (2 "OD, 750mil wall thickness) was 11.5kW. This is much lower than conventional methods using heated containers/blanks.

The ShAPE process is significantly different from friction stir back extrusion (Friction Stir Back Extrusion, FSBE). In FSBE, a rotating mandrel is punched into the contained blank much like a drilling operation. The swirling grooves push the material outward and the material is back-extruded around the mandrel to form a tube, rather than being pushed through a die. As a result, only very small extrusion ratios are possible, the tube is not fully machined with wall thickness, the extrudate cannot be pushed out of the mandrel, and the tube length is limited by the length of the mandrel. In contrast, shAPE utilizes a helical groove on the die face to feed material inwardly through the die and around a mandrel that travels in the same direction as the extrudate. Hereby, a larger outer diameter and extrusion ratio is possible, the material is processed uniformly by the wall thickness, the extrudate can be pushed freely against the centrifugal shaft as in conventional extrusion, and the extrudate length is limited only by the starting volume of the billet.

An example of an arrangement using a ShAPE device and a mandrel 18 is shown in fig. 1 b. Such devices and associated processes have potential to be low cost manufacturing techniques for preparing a variety of materials. As will be described in more detail below, the various mechanical elements of the tool, in addition to modifying various parameters of the process, such as feed rate, heat, pressure, and rotation rate, help achieve various desired results. For example, the varying swirl pattern 14 on the face of the extrusion die 12 may be used to affect/control various characteristics of the resulting material. This may include controlling grain size and crystal texture along the length of the extrusion as well as the wall thickness and other characteristics of the extruded tubing. The change in parameters may be used to advantageously change bulk material properties such as ductility and strength and allow adjustments to be made for specific engineering applications, including changing crush resistance, pressure, or bendability.

The ShAPE process has been used to form various structures from various materials, including the arrangements described in the table below.

TABLE 1

In addition to the disks, rods, and tubes described above, the present disclosure also provides a description of the use of a specially constructed vortex member, referred to by the inventors as an inlet bridge die, that allows for the manufacture of ShAPE extrusions having a non-circular hollow profile. This configuration allows for the use of specially formed inlet bridge dies and associated tools to manufacture extrusions having non-circular and multi-region hollow profiles.

Figures 2 a-2 c show various views of an inlet bridge mold design with a modified swirl face that is unique to operation in the ShAPE process. Fig. 2a shows an isometric view of the swirling face on top of the inlet bridge mold and fig. 2b shows an isometric view of the bottom of the inlet bridge mold with the mandrel visible.

In this embodiment, the grooves 13, 15 on the face 12 of the die 10 direct the plasticized material towards the orifice 17. The plasticized material then passes through the orifice 12, wherein the plasticized material is directed to the die-bearing surface 24 within the welding chamber similar to conventional inlet bridge die extrusion. In this illustrative example, four ports 17 are used to divide the material flow into four different flows as the blank and die are urged against each other as they rotate.

As the outer groove 15 on the die face feeds material inwardly toward the port 17, the inner groove 13 on the die face feeds material radially outwardly toward the port 17. In this illustrative example, for a total of four outwardly flowing grooves, one groove 13 feeds material radially outwardly toward each port 17. The outer groove 15 on the die surface 12 feeds material radially inward toward the port 17. In this illustrative example, for a total of eight inward feed grooves 15, two grooves feed material radially inward toward each port 17. In addition to these two sets of grooves, the peripheral grooves 19 on the outer periphery of the die as shown in fig. 2c are oriented against the die rotation to provide back pressure to minimize material flash between the container and the die during extrusion.

Fig. 2b shows a bottom perspective view of the inlet bridge mold 12. In this view, the mold shows a series of fully penetrating ports 17. In use, the plasticized material flow, which is collected by the above-mentioned inwardly directed grooves 15 and outwardly directed grooves 13, passes through these penetrating portions 17 and then rejoins in the welding chamber 21 and then flows around the mandrel 18 to produce the desired cross section. The use of swirl grooves 13, 15, 19 to feed port 17 during rotation as a means of separating a material flow of raw material (e.g., powder, flakes, billets, etc.) into different flows is never known. This arrangement enables the formation of articles having a non-circular hollow cross-section.

FIG. 3 shows the separation of magnesium alloy ZK60 into multiple streams during the Shape process using an inlet bridge die method. (in this case, the materials are allowed to separate for the effect and explanation of the separation feature, rather than through the mold bearing surfaces for assembly). Conventional extrusion does not rotate and the addition of grooves can greatly impede material flow. But when there is rotation such as in ShAPE or friction extrusion, the swirl not only contributes to the flow but also significantly contributes to the inlet bridge die extrusion 17 functioning and subsequently forming a non-circular hollow profile extrusion. If no vortex grooves are fed to the inlet, extrusion by the inlet bridge die method using a process involving rotation (e.g., shAPE) is ineffective for manufacturing articles having such a configuration. Conventional linear extrusion processes of the prior art do not teach the use of surface features to direct material into the inlet 17 during extrusion.

In the previously described and related applications, various methods and techniques are described, wherein the ShAPE technique and apparatus are shown to provide a number of significant advantages, including the ability to control microstructures (such as crystal texture) through cross-sectional thickness, while also providing the ability to perform a variety of other tasks. In this specification, we provide information about the use of the ShAPE technique to form materials having non-circular hollow profiles, as well as methods for making high entropy alloys that are useful in a variety of applications (e.g., projectiles). These two exemplary applications are discussed in more detail below.

Fig. 4a shows a schematic of a ShAPE process that applies a load/pressure with a rotating tool and at the same time rotation helps to apply a torsional/shear force to generate heat at the interface between the tool and the feedstock to help consolidate the material. In this particular embodiment, the arrangement of the ShAPE protocol is configured to consolidate a high-entropy alloy (HEA) arc melting disk into a dense disk. In this arrangement, the rotary stamping tool is made of inconel (inconel alloy) and has an Outer Diameter (OD) of 25.4mm, and the vortex depth on the stamping face is 0.5mm and has a pitch of 4mm for a total of 2.25 turns. In this case, the stamping surface incorporates a thermocouple to record the temperature at the interface during processing. (see fig. 4 b) this solution enables the stamping to rotate at speeds from 25 to 1500 RPM.

In use, both axial and rotational forces are applied to the material of interest, causing plasticization of the material. In extrusion applications, the plasticized material then flows over a die support surface sized to allow recombination of the plasticized material with a more excellent particle size distribution and alignment than is possible in conventional extrusion processes. As described in the prior related application, this method provides a number of advantages and features that are not realized by conventional prior art extrusion processes alone.

High entropy alloys are generally solid solution alloys formed from five or more principal elements in equal or nearly equal molar (or atomic) ratios. While this arrangement may provide various advantages, it also provides various challenges, particularly in terms of shaping. Whereas conventional alloys typically contain a primary element that largely controls the basic metallurgies of the alloy system (e.g., nickel-based alloys, titanium-based alloys, aluminum-based alloys, etc.), in HEA, each of the five (or more) components of HEA can be considered a primary element. Advances in the production of such materials may open the door for their eventual use in a variety of applications. However, standard forming processes exhibit great limitations in this respect. The hope of achieving such results has been demonstrated using a ShAPE type process.

In one example, a "low density" AICuFe (Mg) Ti HEA is formed. Starting with arc fusion Jin Xiaoqiu (button) as a precursor (pre-cursor), the ShAPE process is used to simultaneously heat, homogenize and consolidate HEA, thereby creating a material that overcomes the various problems associated with prior art applications and provides various advantages. In this particular example, commercially pure aluminum, magnesium, titanium, copper, and iron are used at 10 ^-6 The furnace arc under a backing vacuum melts the HEA pellets. Because of the high vapor pressure of magnesium, most of the magnesium evaporates and forms al1mg0.1cu2.5fe1ti1.5, rather than the intended Al1Mg1Cu1Fe1Ti1 alloy. The arc melted pellets described in the previous paragraph are easily crushed with a hammer and used to fill the die/powder cavity (fig. 4 c) and the shear assisted extrusion process begins. The volume fraction of the filled material was less than 75%, but when the tool was rotated at 500RPM under load control (with the maximum load set at 85MPa and 175 MPa), the material was consolidated.

A comparison of arc melted materials and materials developed under the ShAPE process shows various differences. The arc melted pellets of LWHEA exhibit a dendritic microstructure with nuclei, as well as regions containing intermetallic particles and voids. These microstructural defects were eliminated using the ShAPE process, resulting in single phase, fine grain and pore-free LWHEA samples.

Fig. 5a shows a back-scattered SEM (BSE-SEM) image of an as-cast/arc melted sample. The arc melted samples had a nucleated dendrite microstructure (where dendrites were rich in iron, aluminum, and titanium) and a diameter of 15-30 μm, while the interdendritic regions were rich in copper, aluminum, and magnesium. The aluminum is uniformly distributed throughout the microstructure. This microstructure is typical of HEA alloys. The interdendritic regions appear to be rich in Al-Cu-Ti intermetallic compounds and are verified to be AICu by XRD ₂ Ti. XRD also confirms Cu ₂ Mg phase, which is not determined by EDS analysis, and the entire matrix is BCC phase. The intermetallic compound forms a eutectic structure in the interdendritic region and has a length and width of about 5-10 μm. Inter-dendritic regions are also between themHas a porosity of about 1-2vol% and thus it is difficult to measure the density thereof.

Typically, such microstructures are homogenized by continuous heating for several hours to maintain a temperature close to the melting point of the alloy. In the absence of thermodynamic data and diffusion kinetics for this new alloy system, it is difficult to predict the exact points of formation or precipitation of the various phases, particularly points related to various temperatures and cooling rates. In addition, in the case of the optical fiber,

even after heat treatment, the unpredictability of the persistence of the intermetallic phases and the preservation of their morphology lead to further complications. Typical lamellar and long intermetallic phases are cumbersome when subjected to conventional processing such as extrusion and rolling and are detrimental to mechanical properties (elongation).

The use of the ShAPE process enables refinement of the microstructure without homogenization heat treatment and provides a solution to the above complexity. The arc melted pellets (due to their respective porosity and the presence of intermetallic phases) are easily broken into small pieces to fill the mold cavity of the ShAPE apparatus. As described in table 1, two separate runs were performed, wherein both processes produced disks with a diameter of 25.4mm and a height of about 6 mm. The discs were then sectioned at the center to evaluate the microstructure change as a function of their depth. Typically, during the ShAPE consolidation process; the shearing action causes structural deformation at the interface and increases the interface temperature; this is proportional to rpm and torque; while the linear motion and the heat generated by the shear result in consolidation. Consolidation near full thickness can also be achieved depending on the time of operation and the applied force.

Table 2: consolidation processing conditions for LWHEA

Run #, run #	Pressure (MPa)	Tool RPM	Process temperature	Dwell time
					1	175	500		180s
2	85	500	600℃	180s

Fig. 6 a-6 d show a series of BSE-SEM images ranging from the substantially unprocessed disc bottom to the fully consolidated area at the tool blank interface. There is a gradual change in microstructure from the bottom of the disk to the interface. The bottom of the disc had a microstructure similar to that depicted in fig. 5. But as the puck is inspected to move toward the interface, the dendrite sizes become closely spaced (fig. 6 b). Intermetallic phases remain in the interdendritic regions, but the porosity is completely eliminated. On a macroscopic scale, the disc appears more continuous and there is no void from the top to the bottom 3/4 section. Figure 6c shows an interface where the shearing action is more pronounced. This region clearly distinguishes the as-cast dendrite structure from mixing and plastic deformation caused by shear. A spiral pattern was observed from this area to the top of the disk. This is indicative of the stirring action and is due to the swirling pattern on the surface of the tool. This shearing action also results in comminution of the intermetallic particles and also helps homogenize the material as shown in fig. 6c and 6 d. It should be noted that the entire process lasts only 180 seconds to homogenize, disperse and pulverize the intermetallic particles. Some of these resulting intermetallic particles have a very high probability of redissolving into the matrix. The homogenization area is approximately 0.3mm from the surface of the disk.

The use of the ShAPE apparatus and technique demonstrates a new single step method for processing without preheating the blank. With this new method, the time required to homogenize the material is significantly reduced. Based on early work, the presence of shear and vortex aids in the comminution of the secondary phase and creates a helical pattern. All this provides an important opportunity for cost reduction of the final product without compromising performance and at the same time tuning the microstructure to the desired performance.

Many kinds of alloys exhibit high strength at high temperatures and temperatures, good machinability, high wear resistance and corrosion resistance. Such materials may be considered as alternatives for various applications. Refractory HE alloys can replace expensive superalloys used in applications such as gas turbines and expensive lncon el alloys used in coal gasification heat exchangers. The lightweight HE alloy can be used in automobiles and airplanes instead of aluminum and magnesium alloys. Performing the pinch using the ShAPE procedure will enable these types of deployments.

While various preferred embodiments of the present application have been shown and described, it is to be clearly understood that the application is not limited thereto but may be embodied in various ways for implementation within the scope of the appended claims. From the foregoing, it will be apparent that various changes may be made without departing from the spirit and scope of the application as defined by the following claims.

Claims (12)

1. A shear-assisted extrusion method for forming a non-circular hollow profile extrusion of a desired composition from a feedstock material, the method comprising the steps of:

by pushing a scroll face into a feedstock material while a scroll member of a mold having a scroll face rotates relative to the feedstock material to plasticize the feedstock material against the scroll face, the scroll member is used to apply rotational shear and axial compression forces simultaneously to the feedstock material at the same location, the scroll face has a plurality of grooves defined therein configured to direct plasticized material from a first location at an interface between the feedstock material and the scroll face through the mold to a second location on a mold support surface through an inlet defined in the scroll face, wherein the plasticized feedstock material rejoins at the mold support surface to form a compression.

2. The method of claim 1, wherein the scroll member has a plurality of inlets, each inlet configured to direct plasticized material through the scroll face.

3. The method of claim 2, wherein the grooves on the scroll face comprise a first set of grooves configured to direct plasticized material in a first direction and a second set of grooves configured to direct plasticized material in a second direction, the second direction being different than the first direction.

4. A method according to claim 3, wherein the extrusion of the plasticised material is carried out at a die face temperature of less than 150 ℃.

5. A method according to claim 3, wherein the axial compression force is equal to or below 50MPa.

6. A method according to claim 3, wherein the material is in powder form.

7. A method according to claim 3, wherein the material is a magnesium alloy in the form of a billet, the axial extrusion force is equal to or below 25MPa and the temperature is below 100 ℃.

8. An apparatus for performing shear-assisted extrusion, comprising:

a die comprising a scroll face configured to apply a rotational shear force and an axial compression force to a same preselected location on a feedstock material by pushing the scroll face into the feedstock material while a scroll member rotates relative to the feedstock material to plasticize the feedstock material against the scroll face, wherein a combination of the rotational shear force and the axial compression force at the same location results in plasticization of a portion of the material, the scroll face further comprising at least one recess and an inlet defined within the scroll face;

and a die support surface at which the plasticized material is recombined, wherein the recess is configured to direct a flow of plasticized material through the inlet to a second position on the die support surface, wherein the plasticized feedstock material is recombined at the die support surface after passing through the swirling surface to form an extruded material having a preselected characteristic.

9. A shear-assisted extrusion process for producing high-entropy alloys; the method comprises the following steps:

positioning a preselected high entropy material in contact with an orbiting scroll face within a shear-assist extrusion device, the scroll face having a plurality of grooves and inlets defined therein; and

while providing rotational and axial forces between the material and the scroll face sufficient to cause plasticization and mixing of the material in the grooves of the scroll face and providing plasticized material through the inlet.

10. The method of claim 9, wherein the orbiting scroll has at least two starts.

11. The method of claim 10, wherein the orbiting scroll rotates at a speed of 10 to 1000 revolutions per minute.

12. The method of claim 10, wherein the rotational shear force is less than 50MPa.