Friction Stir Processing for Corrosion Resistance

Abstract

In some examples, techniques are provided for enhancing the corrosion resistance of a component. In some examples, the component includes a granular metallic material. The material is subjected to a friction stir processing operation. The friction stir processing operation includes passing a rotating head of a friction stir welding tool through a surface thickness of the granular metallic material in a treatment path.

Description

[Technical field]

[0001] Claiming priority This application claims priority to U.S. Provisional Patent Application No. 62 / 705,642, filed July 9, 2020, which is incorporated by reference in its entirety.

[0002] The present disclosure relates generally to techniques for enhancing the corrosion resistance of components within a substrate processing chamber, and more particularly to friction stir processing and associated annealing techniques. [Background technology]

[0003] The raw material for some components (e.g., pedestals and showerheads) in substrate processing chambers includes rolled aluminum sheet stock. Typically, this stock is stress-relieved by application of one or more stress-relief techniques, but the resulting microstructure still leaves small elongated grains aligned in the rolling direction. This result runs counter to the desire to create larger grains on the surfaces of aluminum chamber components to reduce corrosion in high-temperature, fluorine-rich substrate processing environments. Fluorine can corrode the component material at the grain boundaries. By increasing the grain size, the density of grain boundaries can be reduced at the surface of the component, thereby reducing corrosion nucleation sites. Uninhibited corrosion can cause the components to release particles that end up on the substrate, leading to significant yield loss for wafer producers, for example. Traditional grain growth techniques, such as the application of high-temperature annealing, have been found to be ineffective in this regard.

[0004] The background discussion set forth herein is provided for general discussion in the context of the present disclosure, and the work of the inventors named herein, to the extent described in this "Background" section, and aspects of the present description that may not otherwise be classified as prior art at the time of filing, are not admitted, explicitly or implicitly, as prior art to the present disclosure. Summary of the Invention

[0005] In some examples, a method of treating a granular metallic material to affect grain size of the material is provided. Exemplary methods include subjecting the material to a friction stir processing operation, the friction stir processing operation including passing a rotating head of a friction stir welding tool in a processing path through a surface thickness of the granular metallic material.

[0006] In some instances, the friction stir processing operation is free of a friction stir welding operation.

[0007] In some examples, the treatment path includes a treatment pattern, the treatment pattern being located within a surface region of the granular metal material.

[0008] In some examples, a first treatment path in the treatment pattern overlaps with a second treatment path in the treatment pattern.

[0009] In some examples, the treatment pattern includes a raster pattern.

[0010] In some examples, the treatment pattern includes a spiral pattern.

[0011] In some examples, the treatment pattern includes a reciprocating pattern.

[0012] In some instances, the treatment pattern includes a serpentine pattern.

[0013] In some instances, the surface thickness of the granular metal material is within the range of 1 to 20 millimeters (approximately 0.4 to 7.9 inches).

[0014] In some examples, the method of treating the granular metal material further comprises subjecting the granular metal material to an annealing operation.

[0015] In some instances, the annealing operation is performed at a temperature within the range of 500-600 degrees Celsius.

[0016] In some instances, the annealing operation is carried out for a duration within the range of 0.01 to 24 hours.

[0017] In some examples, the granular metallic material includes aluminum.

[0018] In some examples, the non-transitory computer-readable storage medium includes instructions that, when executed by a computer, cause the computer to perform a friction stir processing operation on a granular metallic material to affect a grain size thereof, the friction stir processing operation including passing a rotating head of a friction stir welding tool in a treatment path through a surface thickness of the granular metallic material.

[0019] In some examples, the computing device includes a processor and a memory having instructions stored thereon that, when executed by the processor, configure the device to perform a friction stir processing operation on a granular metal material to affect a grain size thereof, the friction stir processing operation including passing a rotating head of a friction stir welding tool in a treatment path through a surface thickness of the granular metal material.

[0020] Some embodiments are illustrated by way of example, and not by way of limitation, in the accompanying drawings. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic diagram of a processing chamber in which some examples of the present disclosure may be used, according to some exemplary embodiments.

[0022] [Diagram 2] FIG. 1 illustrates an overview of a friction stir processing operation, according to an example embodiment.

[0023] [Diagram 3] 1 illustrates a cross-sectional view of a granular metal material according to an example embodiment. [Figure 4] 1 illustrates a cross-sectional view of a granular metal material according to an example embodiment. [Diagram 5] 1 illustrates a cross-sectional view of a granular metal material according to an example embodiment. [Figure 6] 1 illustrates a cross-sectional view of a granular metal material according to an example embodiment.

[0024] [Figure 7] 1 illustrates several operations in a method, according to an example embodiment.

[0025] [Figure 8] FIG. 1 is a block diagram illustrating an example machine by which one or more example embodiments may be implemented or controlled. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The following description includes systems, methods, techniques, instruction sequences, and computer program products embodying exemplary embodiments of the present disclosure. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of the exemplary embodiments. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without these specific details.

[0027] A portion of the disclosure of this patent document may contain material that is subject to copyright protection. The copyright owner has no objection to the copying by anyone of this patent document or the patent disclosure, as it appears in the U.S. Patent Office patent file or records, but otherwise reserves any and all copyrights. The following notice applies to any data in the drawings set forth below and incorporated into this document: Copyright Lam Research Corporation, 2020, All Rights Reserved.

[0028] Referring now to FIG. 1, an exemplary apparatus 100 of a plasma-based processing chamber is shown. While the present subject matter may be used in a wide variety of semiconductor manufacturing and wafer processing operations, in the illustrated example, the plasma-based processing chamber is described in the context of plasma-enhanced or radical-enhanced chemical vapor deposition (CVD) or atomic layer deposition (ALD) operations. Those skilled in the art will recognize that other types of ALD processing techniques (e.g., thermal-based ALD operations) are known and may incorporate non-plasma-based processing chambers. An ALD tool is a specialized type of CVD processing system in which an ALD reaction occurs between two or more chemical species. The two or more chemical species are referred to as precursor gases and are used to form thin film deposits of materials on a substrate, such as silicon wafers used in the semiconductor industry. The precursor gases are sequentially introduced into the ALD processing chamber and react with the surface of the substrate to form a deposition layer. Typically, the substrate is repeatedly reacted with the precursors to slowly deposit increasingly thick layers of one or more material films on the substrate. In some applications, multiple precursor gases may be used to form one or more films of various types during a substrate manufacturing process.

[0029] FIG. 1 is shown including a plasma-based processing chamber 102 with a showerhead 104 (which may be a showerhead electrode) and a substrate support assembly 108 or pedestal disposed therein. Typically, the substrate support assembly 108 provides a substantially isothermal surface and may act as both a heating element and a heat sink for the substrate 106. The substrate support assembly 108 may include an electrostatic chuck (ESC) having a heating element included therein to aid in processing the substrate 106, as described above. The substrate 106 may include, for example, a wafer comprising an elemental semiconductor material (e.g., silicon (Si) or germanium (Ge)) or a compound semiconductor material (e.g., silicon germanium (SiGe) or gallium arsenide (GaAs)). In addition, other substrates include, for example, dielectric materials such as quartz, sapphire, semi-crystalline polymers, or other non-metallic and non-semiconductor materials.

[0030] In operation, a substrate 106 is loaded onto the substrate support assembly 108 through a loading port 110. A gas line 114 can supply one or more process gases (e.g., precursor gases) to the showerhead 104. The showerhead 104 in turn delivers the one or more process gases into the plasma-based processing chamber 102. A gas source 112 (e.g., one or more precursor gas ampoules) for supplying one or more process gases is coupled to the gas line 114. In some examples, a RF (radio frequency) power source 116 is coupled to the showerhead 104. In other examples, the power source is coupled to the substrate support assembly 108 or the ESC.

[0031] Prior to entering the showerhead 104 and downstream gas lines 114, a point-of-use (POU) and manifold combination (not shown) controls the input of one or more process gases into the plasma-based processing chamber 102. In the case of a plasma-based processing chamber 102 used to deposit thin films in a plasma-enhanced ALD operation, precursor gases may be mixed in the showerhead 104.

[0032] In operation, the plasma-based processing chamber 102 is evacuated by a vacuum pump 118. RF power is electrostatically coupled between the showerhead 104 and a lower electrode 120 contained within or on the substrate support assembly 108. The substrate support assembly 108 is typically supplied with two or more RF frequencies. For example, in various embodiments, the RF frequency may be selected from at least one of approximately 1 MHz, 2 MHz, 13.56 MHz, 27 MHz, 60 MHz, and other frequencies as desired. Coils designed to block or partially block specific RF frequencies may be designed as needed. Thus, the specific frequencies discussed herein are merely for ease of understanding. RF power is used to activate one or more process gases into a plasma in the space between the substrate 106 and the showerhead 104. The plasma may assist in depositing various layers (not shown) on the substrate 106. In other applications, the plasma may be used to etch device features into various layers on the substrate 106. RF power is coupled through at least the substrate support assembly 108. The substrate support assembly 108 may have a heater (not shown in FIG. 1) built into it. The detailed design of the plasma-based processing chamber 102 may vary.

[0033] As mentioned above, the raw material for some chamber components, such as the showerhead 104 and the substrate support assembly 108, typically includes rolled aluminum sheet stock. The rolled stock is often stress-relieved, but the resulting microstructure includes small elongated grains aligned in the rolling direction. This small grain microstructure runs counter to the desire to create larger grains at the surface of the aluminum chamber components to reduce corrosion, especially in the high temperature, fluorine-rich substrate processing environment within the processing chamber 102. Fluorine can corrode the component material at the grain boundaries. By increasing the grain size, the density of grain boundaries can be reduced at the surface of the component, thereby reducing corrosion nucleation sites. Uninhibited corrosion can cause the components to release particles that end up on the substrate, leading to significant yield loss for wafer producers, for example. Traditional grain growth techniques, such as the application of high temperature annealing, have been found to be ineffective in this regard.

[0034] Some examples of this that attempt to address these issues use a Friction Stir Welding (FSW) tool. In some examples, the FSW tool is passed over the surface of the chamber component in a spiral or serpentine raster pattern. Some examples include some overlap between passes. These techniques can be referred to in some examples as "friction stir processing" and are significantly different from the standard use of an FSW tool, i.e., to bond two components together along a friction stir weld line. Here, the components are not, or need not be, bonded together. Instead, application of the FSW tool to the surface of the component causes a thermo-mechanical process that breaks down the material particles of the component into much smaller particles. In some examples, the particles include equiaxed (spherical shaped) particles. In some examples, application of the FSW tool to the component surface imparts residual stresses within the material of the component.

[0035] In some instances, a subsequent annealing operation is applied at a temperature in the range of 500-600 degrees Celsius for 1-24 hours (for aluminum) to grow the material particles to a size much larger than the original material. In some instances, friction stir processing involves a solid-state process, which means that the material is not elevated above its melting point (unlike traditional welding), and therefore does not cause alloying of compounds typically used for strengthening, which would diffuse back into the bulk of the material, thereby negating their reinforcing effect.

[0036] In some examples, friction stir processing is applied as a step in the manufacturing process to equalize the chamber components in the intended grain size. In some examples, the equalization step is the last step in the manufacturing process. In some examples, friction stir processing is selectively applied to different regions of the surface of the component. In some friction stir processing examples, appropriate selection of the welding head of the FSW tool and / or one or more process parameters allows for control of grain size. Some examples allow for control of grain size as a function of depth from the free surface of the component. Some examples allow for the ability to trade off strength or thermal conductivity against corrosion resistance in various regions of the component, or on a surface-by-surface basis. Some examples allow for the creation of a uniform or non-uniform appearance on the component surface that may be desired, for example, the component surface closest to the substrate during processing.

[0037] 2, an overview of a friction stir processing operation 200 in a method of treating a granular metallic material is shown. The friction stir processing operation 200 includes passing a rotating head 202 of a friction stir welding tool through a surface thickness 204 of the granular metallic material 206 in an advancement direction 208 of a treatment path 220. In some examples, the surface thickness 204 of the metallic material 206 is within a range of 1 to 20 millimeters (approximately 0.4 to 7.9 inches). A downward force 214 is applied to the FSW tool during the friction stir processing operation 200, which is rotated in a rotational direction 216.

[0038] The metallic material 206 in this example includes aluminum. Other materials or combinations of materials are possible. The metallic material 206 forms a component of a processing chamber, such as the processing chamber 102 of FIG. 1. Example components include the showerhead 104 or the substrate support assembly 108, or subcomponents of either.

[0039] The head 202 of the FSW tool includes a shoulder 210 and a pin 212. Other parts are possible. In the example shown, the pin 212 of the FSW tool engages with the metal material 206. The engagement of the rotating pin 212 (as part of the head 202) with the metal material 206 causes a thermo-mechanical process that breaks down the material particles of the metal material 206. Exemplary aligned grains of the original rolled metal material 206 can be seen in FIG. 3. Exemplary grains resulting from the application of the friction stir processing operation 200 at the treated surface 226 of the metal material 206 can be seen in FIG. 4. It can be seen that the grain size of the metal material 206 has been affected by the friction stir processing operation 200. In this example, the grains are reduced in size and are not aligned. Other effects of the friction stir processing operation 200 are possible. The affected grains are located within an affected zone 218 (or nugget) behind the advancing head 202 of the FSW tool.

[0040] During the friction stir processing operation 200, the advancing rotating head 202 of the FSW tool moves within a treatment path 220. The treatment path 220 may be straight or curved, or may include a single line. In some examples, the treatment path 220 includes a treatment pattern 224. The example treatment pattern 224 is located within an example surface region 222 of the granular metal material 206, as shown.

[0041] In some examples, there is no weld in surface region 222 and there are no other FSW operations in friction stir processing operation 200. In other words, FSW processing operation 200 is not preceded or followed (directly or indirectly) by a conventional FSW operation. In some examples, surface region 222 forms part of a single or monolithic component or uniform metallic material 206, with no seams or assembly features in surface region 222.

[0042] In some examples, the treatment pattern 224 includes a raster pattern, such as generally shown. In some examples, the treatment pattern 224 includes a spiral, reciprocating, serpentine pattern, or a combination of two or more of these patterns. The treatment pattern 224 may traverse a complete or limited extent of the surface area 222. In some examples, a first treatment path in the treatment pattern overlaps with a second treatment path in the treatment pattern. The degree of overlap of the second treatment path with respect to the first treatment path can be within a range of 0.5 to 99 percent, and in some examples, within a range of 1 to 10 percent.

[0043] In some examples, the method of treating the granular metal material includes an annealing operation on the granular metal material. In some examples, the annealing operation is performed after the friction stir processing operation 200. In some examples, the annealing operation is performed at a temperature in the range of 500-600 degrees Celsius. In some examples, the annealing operation is performed for a duration in the range of 1-24 hours.

[0044] Referring to Figure 3, this figure includes a cross-sectional view 300 of a typical rolled metal material 206, in this case aluminum sheet stock. Typically, this stock has been stress-relieved by application of one or more stress-relief or annealing techniques, and as shown, the resulting microstructure is left with small elongated grains 302 aligned in the rolling direction. As discussed above, this alignment and / or smaller size of the grains runs counter to the desire to create larger grains on the surfaces of aluminum chamber components, for example to reduce corrosion in high temperature, fluorine-rich substrate processing environments. Fluorine can corrode the component material at the grain boundaries.

[0045] Referring to Figure 4, this figure includes a corresponding cross-sectional view 400 of the same metallic material 206 as Figure 3, but taken after the friction stir processing operation 200 and prior to annealing. The friction stir processing operation 200 has an effect on the size of the grains 402, causing a relative grain size reduction in this example, as shown.

[0046] Referring to FIG. 5, this figure includes a corresponding cross-sectional view 500 of the same metallic material 206 as FIGS. 3 and 4, but taken after an annealing operation has been performed on the metallic material 206. In some examples, the annealing operation is performed after the friction stir processing operation 200. In some examples, the annealing operation is performed at a temperature in the range of 500-600 degrees Celsius. In some examples, the annealing operation is performed for a duration in the range of 1-24 hours. The annealing operation affects the size of the grains 502, in this example causing a relative and significant grain size increase.

[0047] FIG. 6 illustrates the friction stir processing operation 200 and subsequent 525 ℃1 includes an enlarged cross-sectional view 600 of a surface thickness 204 of a metallic material 206 that has been fully treated by an annealing operation at 1000° C. for 16 hours. Large grains 502 have been formed by the friction stir processing operation 200 and can be observed in each treatment path 220 of the head 202 of the FSW tool. In this example, a treatment pattern 224 including a raster pattern is used such that two of the treatment paths 220 (e.g., first and third) proceed away from the reader (into the page) and two of the treatment paths 220 (e.g., second and fourth) proceed towards the reader (away from the page). In this example, the treatment paths 220 overlap at the treated surface 226 of the metallic material 206. By growing the size of the grains 502 thanks to the friction stir processing operation 200 and the subsequent annealing operation, the density of grain boundaries 602 on the treated surface 226 of the component has been reduced, thereby reducing corrosion nucleation sites on the component during substrate processing. The untreated regions 604 show the maintained microstructure of the original rolled stock of Figure 3. The increased overlap of the treatment paths 220 in the treatment pattern 224 tends to transform these untreated regions 604 into large grain regions.

[0048] Some embodiments herein include methods. With reference to FIG. 7, at operation 702, the method 700 of treating a granular metallic material includes performing a friction stir processing operation on the metallic material. The friction stir processing operation includes passing a rotating head of a friction stir welding tool through a surface thickness of the granular metallic material in a treatment path. At operation 704, the method 700 of treating a granular metallic material includes utilizing a treatment pattern including one or more treatment paths. The method 700 may include further operations as summarized above or described elsewhere herein.

[0049] FIG. 8 is a block diagram illustrating an example of a machine or controller 800 by which one or more exemplary embodiments described herein may be implemented or controlled. In alternative embodiments, the controller 800 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the controller 800 may operate in the role of a server machine, a client machine, or both in a server-client network environment. In one example, the controller 800 may act as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. Furthermore, although only a single controller 800 is shown, the term "machine" (controller) is also to be construed as any collection of machines (controllers) that individually or jointly execute a set (or sets) of instructions to perform any one or more of the methodologies discussed herein, such as through cloud computing, software as a service (SaaS), or other computer cluster configurations. In some examples, and with reference to FIG. 8, the non-transitory machine-readable medium includes instructions 824 that, when read by the controller 800, cause the controller to control operations in a manner that includes at least the non-limiting example operations described herein.

[0050] The examples described herein may include or operate with logic circuits, several components, or mechanisms. Circuitry is a collection of circuits implemented in a tangible entity, including hardware (e.g., simple circuits, gates, logic circuits, etc.). The membership of the circuitry may be flexible over time and underlying hardware variability. When operating, the circuitry may perform specified operations, either alone or in combination. In one example, the hardware of the circuitry may be invariably designed (e.g., hardwired) to perform specific operations. In one example, the hardware of the circuitry may include variably connected physical components (e.g., execution units, transistors, simple circuits, etc.) including computer-readable media that are physically altered (e.g., magnetically, electrically, by movable arrangement of immutable mass particles, etc.) to encode instructions for specific operations. In connecting the physical components, the underlying electrical properties of the hardware constructs are changed (e.g., from insulator to conductor or vice versa). The instructions enable the embedded hardware (e.g., an execution unit or a load mechanism) to create, through variable connections, members of the circuitry in the hardware to perform some portion of a particular operation when in operation. Thus, the computer-readable medium is communicatively coupled to other components of the circuitry when the device is in operation. In one example, any one of the physical components may be used in two or more members of two or more circuitries. For example, during operation, an execution unit may be used in a first circuit of a first circuitry at one time and reused by a second circuit in the first circuitry or by a third circuit in the second circuitry at a different time.

[0051] The machine (e.g., computer system) controller 800 may include a hardware processor 802 (e.g., a central processing unit (CPU), a hardware processor core, or any combination thereof), a GPU 832 (graphics processing unit), a main memory 804, and a static memory 806, some or all of which may communicate with each other through an interlink 808 (e.g., a bus). The controller 800 may further include a display device 810, an alphanumeric input device 812 (e.g., a keyboard), and a UI navigation device 814 (e.g., a mouse or other user interface). In one example, the display device 810, the alphanumeric input device 812, and the UI navigation device 814 may be touch screen displays. The controller 800 may additionally include a mass storage device 816 (e.g., a drive unit), a signal generation device 818 (e.g., a speaker), a network interface device 820, and one or more sensors 830, such as a global positioning system (GPS) sensor, a compass, an accelerometer, or other sensor. The controller 800 may include an output controller 828, such as a serial (e.g., Universal Serial Bus (USB)), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection, for communicating with or controlling one or more peripheral devices (e.g., a printer, card reader, etc.).

[0052] The mass storage device 816 may include a machine-readable medium 822 on which is stored one or more sets of data structures or instructions 824 (e.g., software) that embody or are utilized by any one or more of the techniques or functions described herein. The instructions 824 may also reside, completely or at least partially, within the main memory 804, within the static memory 806, within the hardware processor 802, or within the GPU 832 during their execution by the controller 800, as shown. In one example, one or any combination of the hardware processor 802, GPU 832, main memory 804, static memory 806, or mass storage device 816 may constitute the machine-readable medium 822.

[0053] Although the machine-readable medium 822 is shown as a single medium, the term “machine-readable medium” may include a single medium or multiple media (e.g., a centralized or distributed database, and / or associated caches and servers) configured to store one or more instructions 824.

[0054] The term "machine-readable medium" may include any medium capable of storing, encoding, or retaining instructions 824 for execution by the controller 800, causing the controller 800 to perform any one or more of the techniques of this disclosure, or capable of storing, encoding, or retaining data structures used by or associated with such instructions 824. Non-limiting examples of machine-readable media may include solid-state memory, and optical and magnetic media. In one example, a large-scale machine-readable medium comprises a machine-readable medium 822 having a plurality of particles having an unchanging (e.g., stationary) mass. Thus, the large-scale machine-readable medium is not a transitory propagating signal. Particular examples of large-scale machine-readable media may include non-volatile memory, such as semiconductor memory devices (e.g., electrically programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM)) and flash memory devices, magnetic disks such as internal hard disks and removable disks, magneto-optical disks, and CD-ROM and DVD-ROM disks. The instructions 824 may further be transmitted or received over a communications network 826 using a transmission medium through the network interface device 820 .

[0055] Although the examples have been described with reference to certain exemplary embodiments or methods, it will be apparent that various modifications and changes can be made to these embodiments without departing from the broader scope of the embodiments. Thus, the specification and drawings should be considered in an illustrative and not a restrictive sense. The accompanying drawings, which form a part of this specification, show, by way of example and not by way of limitation, specific embodiments in which the present subject matter may be practiced. The illustrated embodiments are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed herein. Other embodiments can be utilized and derived therefrom, such that structural and logical substitutions and changes can be made without departing from the scope of the present disclosure. Thus, this detailed description should not be taken in a limiting sense, and the scope of the various embodiments is defined solely by the appended "claims," ​​along with the full range of equivalents to which such claims are entitled.

[0056] Such embodiments of the present inventive subject matter may be referred to herein individually and / or collectively under the term "invention" merely for convenience, without the intention of spontaneously limiting the scope of this application to any single invention or inventive concept when in fact more than one is disclosed. Thus, although specific embodiments have been shown and described herein, it should be understood that any arrangement intended to achieve the same purpose may be substituted for the specific embodiment shown. The present disclosure is intended to encompass any adaptations or variations of the various embodiments. Combinations of the above embodiments, as well as other embodiments not specifically described herein, will be apparent to those skilled in the art upon consideration of the above description. The present invention can be realized, for example, in the following manner. Application example 1: 1. A method of treating a granular metal material to affect its grain size, comprising the steps of: The method includes subjecting the material to a friction stir processing operation, the friction stir processing operation including passing a rotating head of a friction stir welding tool in a treatment path through a surface thickness of the granular metallic material. Application example 2: The method of application example 1, wherein the friction stir processing operation is not a friction stir welding operation. Application example 3: A method according to application example 1, wherein the treatment path includes a treatment pattern, the treatment pattern being located within a surface region of the granular metal material. Application example 4: A method according to application example 3, wherein a first treatment path in the treatment pattern overlaps with a second treatment path in the treatment pattern. Application example 5: The method of application example 3, wherein the treatment pattern includes a raster pattern. Application example 6: The method of application example 3, wherein the treatment pattern includes a spiral pattern. Example 7: The method of application example 3, wherein the treatment pattern includes a reciprocating pattern. Application example 8: The method of application example 3, wherein the treatment pattern includes a serpentine pattern. Example 9: The method of application example 1, wherein the surface thickness of the granular metal material is within the range of 1 to 20 millimeters (approximately 0.4 to 7.9 inches). Example 10: The method of Application Example 1, wherein the method of treating the granular metal material further comprises performing an annealing operation on the granular metal material. Example 11: The method of application example 10, wherein the annealing step is performed at a temperature in the range of 500 to 600 degrees Celsius. Application example 12: The method of application example 10, wherein the annealing operation is carried out for a duration in the range of 0.01 to 24 hours. Application example 13: The method of application example 1, wherein the granular metal material comprises aluminum. Example 14: A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform operations, the operations including at least 1. A computer-readable storage medium comprising: performing a friction stir processing operation on a granular metallic material to affect a grain size thereof, the friction stir processing operation comprising passing a rotating head of a friction stir welding tool in a treatment path through a surface thickness of the granular metallic material. Application example 15: 1. A computing device, comprising: A processor; and a memory storing instructions that, when executed by the processor, configure the computing device to perform tasks, the tasks including at least 1. A computing device comprising: performing a friction stir processing operation on a granular metallic material to affect a grain size thereof, the friction stir processing operation comprising passing a rotating head of a friction stir welding tool in a treatment path through a surface thickness of the granular metallic material.

Claims

1. 1. A method of treating a granular metal material to affect its grain size, comprising the steps of: subjecting the granular metal material to a friction stir processing operation and an annealing operation; the granular metal material comprises aluminum; the friction stir processing operation includes passing a rotating head of a friction stir welding tool through a surface thickness of the granular metallic material in a treatment path; The method wherein said annealing operation is carried out at a temperature in the range of 500-600 degrees Celsius and for a duration in the range of 1-24 hours.

2. The method of claim 1 , wherein the friction stir processing operation is free of a friction stir welding operation.

3. The method of claim 1 , wherein the treatment path includes a treatment pattern, the treatment pattern being located within a surface region of the granular metal material.

4. The method of claim 3 , wherein a first treatment path in the treatment pattern overlaps with a second treatment path in the treatment pattern.

5. The method of claim 3 , wherein the treatment pattern comprises a raster pattern.

6. The method of claim 3 , wherein the treatment pattern comprises a spiral pattern.

7. The method of claim 3 , wherein the treatment pattern comprises a reciprocating pattern.

8. The method of claim 3 , wherein the treatment pattern comprises a serpentine pattern.

9. 10. The method of claim 1, wherein the surface thickness of the granular metal material is within the range of 1 to 20 millimeters (approximately 0.4 to 7.9 inches).

10. A computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform operations, the operations including at least performing friction stir processing and annealing operations on the granular metallic material to affect its grain size; the granular metal material comprises aluminum; the friction stir processing operation includes passing a rotating head of a friction stir welding tool through a surface thickness of the granular metallic material in a treatment path; The computer-readable storage medium, wherein the annealing operation is performed at a temperature in the range of 500-600 degrees Celsius and for a duration in the range of 1-24 hours.

11. 1. A computing device, comprising: A processor; and a memory storing instructions that, when executed by the processor, configure the computing device to perform tasks, the tasks including at least performing friction stir processing and annealing operations on the granular metallic material to affect its grain size; the friction stir processing operation includes passing a rotating head of a friction stir welding tool through a surface thickness of the granular metallic material in a treatment path; The annealing operation is performed at a temperature in the range of 500-600 degrees Celsius and for a duration in the range of 1-24 hours.

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