Method for joining dissimilar metals in the absence of harmful intermetallic compounds

Abstract

A method of joining a first component and a second component made of dissimilar metals. In some embodiments, the method includes applying a frictional force between the first component and the second component, the frictional force being sufficient to generate a quasi-liquid metal layer at the dissimilar metal interface between the first component and the second component and to produce shear localization within the quasi-liquid metal; and terminating the application of the frictional force at a predetermined time after the generation of the quasi-liquid metal. In some embodiments, the method includes applying an amorphous metal at the dissimilar metal interface, between at least a portion of the first component and the second component; heating the amorphous metal to a temperature between its glass transition temperature (T g ) and the lowest melting temperature of the components included; and applying a compressive pressure to produce thermoplastic deformation of the amorphous metal.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of U.S. Utility Patent Application No. 17 / 126,987, filed on December 18, 2020, and claims the benefit of U.S. Provisional Application No. 62 / 956,368, filed on January 2, 2020. The entire disclosure of the above applications is incorporated herein by reference. Technical field

[0003] The present disclosure relates to joining dissimilar metals, and more particularly to using quasi - liquid metal to join dissimilar metals. Background art

[0004] This section provides background information related to the present disclosure, which is not necessarily prior art. This section provides an overall overview of the present disclosure rather than a full disclosure of its entire scope or all features.

[0005] By introducing brittle intermetallic compounds at the joining interface through fusion - based methods (e.g., arc or high - energy beam) or solid - state methods (e.g., ultrasonic welding, conventional friction welding, and conventional friction stir welding), directly joining incompatible dissimilar metals (e.g., Al / Fe, Ti / Fe, Mg / Fe, etc.) makes the resulting welds unsuitable for safety - critical engineering structures. Traditional methods focus on metallurgy that affects phase - change kinetics and diffusion by reducing the processing peak temperature and / or increasing the cooling rate during manufacturing. Unfortunately, these methods only result in a gradual decrease in the size of the intermetallic compounds at the joining interface. The problem remains unresolved. Summary of the invention

[0006] According to the principles of the present teachings, a method of joining a first component and a second component made of dissimilar metals is provided. In some embodiments, the method includes applying rapid friction between the first component and the second component, the rapid friction being sufficient to generate a quasi - liquid metal layer and shear localization at the interface between the first component and the second component, and terminating the application of the rapid friction after a predetermined time after the generation of the quasi - liquid metal and shear localization. In some embodiments, the method of joining the first component and the second component includes applying an amorphous metal between the first component and the second component and heating the amorphous metal to a temperature above its glass transition temperature (T g) and at a temperature below the lowest melting temperature of the components included to transform the amorphous metal into a quasi-liquid metal, and apply a compression pressure to deform the quasi-liquid metal. The method according to the present disclosure can fabricate stronger dissimilar metal structures in a novel and cost-effective way, thereby minimizing the presence of harmful intermetallic compounds.

[0007] Based on the description provided herein, other application areas will become apparent. The description and specific examples in this summary of the invention are for illustrative purposes only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The drawings described herein are for illustrative purposes only for the selected embodiments and not for all possible implementations, and are not intended to limit the scope of the present disclosure.

[0009] Figure 1A and Figure 1B is a molecular dynamics (MD) simulation showing the formation of a quasi-liquid metal under rapid sliding (friction) conditions during sliding according to the principles of the present teachings; Figure 1A shows the atomic positions at the first time, and Figure 1B shows the atomic displacements during the 3 ps period.

[0010] Figure 2 is a high-resolution transmission electron microscopy observation result of the interfacial layer or bonding interface between steel (Fe) and aluminum alloy (Al) according to the principles of the present teachings.

[0011] Figure 3 is a three-dimensional (3D) spatial image provided by atom probe tomography showing the atomic chemical deposition across the Al-Fe joint interface and a composition map taken along line A-A.

[0012] Figure 4 is a cross-sectional schematic view of in-situ generation of a quasi-liquid metal along a dissimilar metal interface through high-speed frictional force between a first component and a second component.

[0013] Figure 5 is a cross-sectional schematic view of a system for generating local activated high-speed frictional force at a bimetallic interface by inserting a rotating tool through a first component to in-situ generate a quasi-liquid metal at the dissimilar metal interface, thereby producing a lap joint.

[0014] Figure 6It is a cross-sectional schematic diagram of a system for generating a locally activated rapid frictional force at a bimetallic interface by inserting a rotating tool through a first component, in order to in-situ generate a quasi-liquid metal at a dissimilar metal interface, thereby producing a butt joint.

[0015] Figure 7 It is a cross-sectional schematic diagram of a system for generating a locally activated rapid frictional force at a bimetallic interface by inserting a rotating tool through a first component, in order to in-situ generate a quasi-liquid metal at a dissimilar metal interface, thereby producing beveled joints.

[0016] Figure 8 It is a cross-sectional schematic diagram of a system showing a shallow groove formed on a second component under a first component before welding.

[0017] Figure 9 It is a cross-sectional schematic diagram of a system showing the use of one or more positioning struts extending from the bottom of a probe section to maintain the distance between the probe section and a bonding line.

[0018] Figure 10 It is a cross-sectional schematic diagram of a system showing that a shoulder and a probe section can be operated independently.

[0019] Figure 11 It is a cross-sectional schematic diagram of a system showing the joining of three components.

[0020] Figure 12 It shows various cross-sectional shapes of a probe section (including circular, polygonal or irregular shapes); and surface features added on the probe surface to increase the surface roughness of the probe section.

[0021] Figure 13 It is a cross-sectional schematic diagram of a system having one or more annular positioning struts.

[0022] Figure 14 It is a cross-sectional schematic diagram of a system having one or more annular positioning struts for a beveled faying surface.

[0023] Figure 15 It is a cross-sectional schematic diagram of a system having one or more annular positioning struts and three components.

[0024] Figure 16 It is a cross-sectional schematic diagram of a system having double shoulders for constraining material flow.

[0025] Figure 17 It is a cross-sectional schematic diagram of a system showing spot joint binding by applying an external amorphous metal.

[0026] Figure 18 is a linear lap joint manufactured by introducing an external amorphous metal and integrating an external tool.

[0027] Figure 19 is a linear butt joint manufactured by introducing an external amorphous metal.

[0028] Figure 20 is a linear lap joint manufactured by introducing an external amorphous metal and separate heating, as well as a compression tool.

[0029] Throughout several views of the accompanying drawings of the specification, corresponding reference numerals refer to corresponding components. Detailed Description

[0030] Embodiment implementations will now be described more fully with reference to the accompanying drawings.

[0031] Embodiment implementations are provided that will make the present disclosure thorough and will fully convey the scope to those skilled in the art. Numerous specific details (such as examples of specific components, devices, and methods) are set forth to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that the embodiment implementations may be embodied in many different forms without the use of specific details, and the specific details should not be construed as limiting the scope of the present disclosure. In some embodiment implementations, well-known processes, well-known device structures, and well-known technologies have not been described in detail.

[0032] The terms used herein are for the purpose of describing particular embodiment implementations only and are not intended to be limiting. As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" may be intended to include the plural forms. The terms "comprises", "comprising", "including", and "having" are inclusive and thus specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. Unless explicitly identified as the order of execution, the method steps, processes, and operations described herein should not be construed as necessarily being performed in the particular order discussed or illustrated. It should also be understood that additional or alternative steps may be employed.

[0033] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it can be directly on, engaged directly to, connected directly to, or coupled directly to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a like manner (e.g., “between” relative to “directly between,” “adjacent” relative to “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0034] Although the terms “first,” “second,” “third,” etc. may be used herein to describe different elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections are not to be limited by these terms unless otherwise specified. These terms may be used only to distinguish one element, component, region, layer, and / or section from another. When used herein, terms such as “first,” “second,” and other numerical terms do not imply an order or sequence unless the context clearly dictates otherwise. Thus, a first element, first component, first region, first layer, or first section discussed below may be referred to as a second element, second component, second region, second layer, or second section without departing from the teachings of the embodiments.

[0035] For ease of description, spatial relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” etc., may be used herein to describe the relationship of one element or feature to another (other) element or feature shown in the figures. Spatial relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as “below” or “beneath” another element or feature will then be oriented “above” the other element or feature. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatial relative descriptors used herein are to be interpreted accordingly.

[0036] In accordance with the teachings of the present disclosure, as shown in FIGS. 1-20, a method and system for joining at least a first component 10 and a second component 12 with a novel method for controlling the microstructure of dissimilar metal interfaces are disclosed. It should be understood that, as shown herein (see Figure 11 and Figure 15 ), this teaching is equally applicable to joining more than two components (such as a first component 10, a second component 12, and a third component 13).

[0037] In some embodiments, the first component 10 is made of a dissimilar metal relative to the metal of the second component 12. In this way, a quasi-liquid metal 16 and shear localization within the quasi-liquid metal 16 can be generated and maintained at the dissimilar metal interface 14, which is disposed between the first component 10 and the second component 12. In some embodiments, such a quasi-liquid metal 16 can be generated by the rapid frictional force between the first component 10 and the second component 12. The quasi-liquid metal herein can be defined as a metal that is liquid-like at a temperature below the melting point of the metal. The quasi-liquid metal has a higher viscosity than the melton liquid metal.

[0038] Specific reference is made to Figure 1A and Figure 1B to provide molecular dynamics (MD) simulations to illustrate the formation of the quasi-liquid metal 16 under rapid sliding (friction) conditions in accordance with the principles of this teaching. Figure 1A It is shown that the first component 10 (e.g., made of aluminum alloy (Al)) is in physical contact with the second component 12 (e.g., made of steel (Fe)) along the dissimilar metal interface 14. The rapid frictional sliding applied between the first component 10 and the second component 12 is sufficient to generate a layer of the quasi-liquid metal 16 and shear localization at the dissimilar metal interface 14 between the first component 10 and the second component 12, as Figure 1A shown.

[0039] In accordance with this teaching, the formation of the quasi-liquid metal 16 and shear localization within the quasi-liquid metal 16 promote alloy amorphization at the dissimilar metal interface 14. A nanoscale amorphous layer 18 has been successfully and repeatedly produced at the dissimilar metal interface 14 on bimetallic samples. As Figure 2 shown, in some embodiments, the transition region between the first component 10 and the second component 12 is not an intermetallic compound, but a nanoscale amorphous metal or layer 18 having an average thickness of about 10 nanometers.

[0040] As Figure 3As shown, detailed atomic probe tomography (ATP) examinations have revealed that the nanoscale amorphous layer 18 is indeed formed and has a composition corresponding to that of a "metallic glass former" composition. Such metallic glassy compositions can typically only be achieved by rapid solidification in the range of 10 5 to 10 6 °C / s. However, in accordance with the principles of the present teachings, we have found that through experimental joining tests, the present teachings can achieve the desired composition at a cooling rate of less than 10 2 °C / s. This difference is caused by the formation of a quasi-liquid metal 16 at the dissimilar metal interface 14 produced by the method of the present teachings.

[0041] The above findings have led to two classes of novel dissimilar manufacturing processes that can be used to produce stronger dissimilar metal structures:

[0042] 1) In-situ generation of the quasi-liquid metal 16 at the dissimilar metal interface 14 by shear localization caused by rapid friction within the quasi-liquid metal 16 beyond a threshold shear strain rate; and

[0043] 2) Application of the quasi-liquid metal 16 by adding a metallic glass that has good thermoplastic formability at elevated temperatures.

[0044] First, as noted, in some embodiments, at certain contact pressure and relative velocity conditions, in-situ generated quasi-liquid metal 16 can be obtained through rapid friction between a first component 10 and a second component 12 made of dissimilar metals, thereby causing a shear strain rate higher than the threshold shear strain rate. The threshold shear strain rate within the quasi-liquid metal 16 is estimated to be 1x10 4 s -1 or higher than 1x10 4 s -1 . After sufficient quasi-liquid metal 16 has formed at the dissimilar metal interface 14 and before crystallization occurs within the quasi-liquid metal 16, the rapid frictional force needs to be terminated and the processing temperature needs to be reduced to a temperature below the crystallization temperature of the quasi-liquid metal 16. In some embodiments, after sufficient quasi-liquid metal 16 has formed at the dissimilar metal interface 14 and before significant crystallization occurs within the quasi-liquid metal 16, the rapid frictional force needs to be terminated and the processing temperature needs to be reduced to a temperature below the crystallization temperature of the quasi-liquid metal 16. In some embodiments, significant crystallization means that 80% of the quasi-liquid metal has crystallized.

[0045] Second, as noted, in some embodiments, a metallic glass (the glass transition temperature (T g)applying the near - liquid metal 16 at a temperature (lower than 90% of the lowest melting point of the metal to be welded): (1) positioning the metallic glass at the dissimilar - metal interface 14; (2) heating the metallic glass to a temperature higher than the transformation T g but lower than the lowest melting point of the included metals; (3) applying a compressive pressure to cause thermoplastic deformation; and (4) before crystallization occurs, reducing the welding temperature to below the crystallization temperature of the near - liquid metal 16. In some embodiments, before a large amount of crystallization occurs, the welding temperature needs to be reduced to below the crystallization temperature of the near - liquid metal 16. In some embodiments, a large amount of crystallization means that 80% of the near - liquid metal has crystallized.

[0046] As Figure 4 shown, in some embodiments, in - situ generation of the near - liquid metal 16 can be achieved by applying a rapid frictional force, by applying a pressure P, and by relative movement between the first component 10 and the second component 12. The rapid frictional force between the first component 10 and the second component 12 needs to be sufficient to cause interfacial pre - melting (i.e., form a thin layer of the near - liquid metal 16) and shear localization within the near - liquid metal 16 at the dissimilar - metal interface 14. In some embodiments, after sufficient near - liquid metal 16 is formed at the dissimilar - metal interface 14 and before crystallization occurs within the near - liquid metal 16, the rapid frictional force needs to be terminated, and the processing temperature needs to be reduced to a temperature below the crystallization temperature of the near - liquid metal 16.

[0047] In some embodiments, a near - liquid metal 16 thicker than 100 nm at the dissimilar - metal interface 14 is sufficient. In some embodiments, a near - liquid metal 16 thicker than 10 nm at the dissimilar - metal interface 14 is sufficient.

[0048] In some embodiments, once sufficient near - liquid metal 16 is formed, the relative movement between the first component 10 and the second component 12 needs to be terminated within 1 - 3 seconds. In some embodiments, once sufficient near - liquid metal 16 is formed, the relative movement between the first component 10 and the second component 12 needs to be terminated within 3 - 5 seconds.

[0049] In some embodiments, the first component 10 and the second component 12 each have a surface 20 - - the surface 20a of one component (a) is configured to bond to the surface 20b of the other component (b). In such a way, one or more surfaces 20 of each of the first component 10 and the second component 12 will be referred to as mating surfaces 20, and the one or more surfaces are configured to be joined, welded, or assembled. The joining, welding, or assembly of the mating surfaces 20 of the first component 10 and the second component 12 occurs along the dissimilar - metal interface 14.

[0050] In some embodiments, to improve the quality of the bond, contaminants on the mating surface 20 of the first component 10 and the second component 12 should be removed before bonding, welding, or assembly. In some embodiments, surface contaminants can be removed by grinding. In some embodiments, surface contaminants can be removed by organic solvents. In some embodiments, surface oxidation on the mating surface 20 can be removed or reduced to a thickness less than 2 nm before the welding or assembly process. In some embodiments, the mating surface 20 can be flat. In some embodiments, as Figure 8 shown, the mating surface 20 can be concave to form a shallow groove, thereby enhancing the rapid frictional force at the dissimilar material interface 14. In some embodiments, the shape of the mating surface 20 of the first component 10 can be complementary to the mating surface of the second component 12. In some embodiments, the shape of the mating surface 20 of the first component 10 can be different from the mating surface of the second component 12.

[0051] In some embodiments, the mating surface 20 of the harder component (i.e., the first component 10 or the second component 12) can have and / or be flattened to a roughness of R a <0.025 μm. In some embodiments, the mating surface 20 of the harder component can have and / or be flattened to a roughness of R a <0.1 μm. In some embodiments, the mating surface 20 of the harder component can have and / or be flattened to a roughness of R a <1 μm. In some embodiments, the mating surface 20 of the harder component can have and / or be flattened to a roughness of R a <5 μm.

[0052] Referring to Figures 5 - 7 , in some embodiments, the quasi-liquid metal 16 generated in-situ at the dissimilar metal interface 14 can be achieved by inserting a rotary tool 110 through at least one of the first component 10 and the second component 12 to generate a locally activated rapid frictional force at the dissimilar metal interface 14. In some embodiments, the rotary tool 110 can include any of the various cross-sectional shapes described herein. In some embodiments, the rotary tool 110 can include one or more shoulders 112 and one or more probe members 114 extending from the shoulders 112. In some embodiments, as Figure 16 shown, the rotary tool 110 includes two shoulders 112. At least a portion of the probe member 114 physically contacts at least one of the first component 10 and the second component 12 to generate a rapid frictional force at the dissimilar metal interface 14.

[0053] In some embodiments, as Figure 10 and Figure 16As shown, the shoulder 112 and the probe portion 114 can rotate independently and / or move independently in the axial direction. In some embodiments, the shoulder 112 and the probe portion 114 can rotate independently. In some embodiments, only the probe member 114 rotates.

[0054] In some embodiments, the probe member 114 has at least one side surface 116 and at least one distal surface 118. In some embodiments, at least one distal surface 118 can be concave, convex, or flat, or various combinations thereof. In some embodiments, as Figure 12 shown, the cross-sectional shape of the probe member 114 can be circular, polygonal, or irregular.

[0055] In some embodiments, surface features that can increase surface roughness can be added to the rotary tool 110 (such as the probe member 114) to enhance the rotational flow of the material around the rotary tool member 110, thereby enhancing the rapid frictional force of local activation between dissimilar metals. In some embodiments, the probe member 114 can promote the rotation of the quasi-liquid metal around the probe member 114, and the shoulder 112 (having a larger diameter than the probe member 114) can act as a shoulder or a barrier to inhibit or prevent the quasi-liquid metal from flowing out of the processing area.

[0056] In some embodiments, as Figures 9 - 11 shown, the rotary tool 110 can include positioning props 120 extending from the distal surface 118 of the probe member 114, from the side surface 116, or a combination thereof. In some embodiments, the rotary tool 110 can include positioning props 120 extending from the side surface 116 of the probe member 114. In some embodiments, the rotary tool 110 can include positioning props 120 extending from the distal surface 118 of the probe member 114. In some embodiments, the positioning props 120 are located at the center of the distal surface 118 of the probe member 114. In some embodiments, the positioning props 120 are offset from the center of the distal surface 118 of the probe member 114. In some embodiments, multiple positioning props 120 are used.

[0057] In some embodiments, as Figure 13As shown, the positioning strut 120 may include one or more loop-like members extending from the side surface 116 of the probe member 114. In some embodiments, the positioning strut 120 extends completely around the probe member 114. In some embodiments, the positioning strut 120 extends only around a portion of the probe member 114. In some embodiments, the positioning strut 120 is axially centered on the probe member 114. In some embodiments, the positioning strut 120 can be used to create a docking joint. In some embodiments, multiple loops can be used as the positioning strut 120. In some embodiments, the end surface of the positioning strut 120 is flat.

[0058] In some embodiments, the positioning strut 120 is configured to provide a standoff distance from the dissimilar metal interface 14. For example, in some embodiments, as Figures 9 - 11 shown, the probe member 114 of the rotary tool 110 can be spaced from the dissimilar metal interface 14 by a standoff distance, h. Although this standoff distance h can be achieved in a variety of ways (as shown and described herein), one or more positioning struts 120 can extend from the distal surface 118 and have a length equal to the standoff distance h such that the positioning strut 120 can contact the mating surface 20 of the second component 12 to ensure proper positioning of the probe member 114 of the rotary tool 110. In some embodiments, regardless of whether related to the positioning strut 120, the standoff distance h (and thus the length of the positioning strut 120) can be about 0.05 to 1 mm. In some embodiments, the surface area of the distal surface of the positioning strut 120 can be about 60% of the surface area of the distal surface 118 of the probe member 114.

[0059] In some embodiments, the positioning strut 120 can be in close contact with the mating surface 20 of the second component 12. In some embodiments, the positioning strut 120 can slightly penetrate the mating surface 20 of the second component 12. In some embodiments, the relative positioning between the positioning strut 120 and the mating surface 20 is controlled by monitoring and controlling the reaction force applied to the positioning strut 120.

[0060] In some embodiments, as Figure 14 shown, the end surface of the positioning strut 120 is parallel to the mating surface 20. In some embodiments, the end surface of the positioning strut 120 is a regular shape. In some embodiments, the end surface of the positioning strut 120 is an irregular shape. In some embodiments, the end surface of the positioning strut 120 is pointed.

[0061] In some embodiments, the positioning struts 120 of the probe member 114 and the probe member 114 are made of the same material. In some embodiments, the positioning struts 120 of the probe member 114 and the probe member 114 are made of different materials. In some embodiments, the positioning struts 120 of the probe member 114 are made of a harder and more wear-resistant material than the probe member 114.

[0062] In some embodiments, the rotary tool 110 can be inserted through a component (10, 12) having a relatively low melting point compared to other components (12, 10). In some embodiments, the rotary tool 110 travels in the welding direction to produce a long butt or lap joint.

[0063] In some embodiments, interfacial amorphization by adding metallic glass 130 (also known as amorphous metal) can be used to produce a point joint 132( Figure 17 ). The amorphous metal can be inserted and then heated to a temperature above its glass transition temperature (T g ) and below the lowest melting point of all the components included by frictional energy, inductive energy or other heating sources. Once the amorphous metal is heated to the target temperature, the metallic glass exists as a highly viscous liquid metal and increases its fluidity. Compressive pressure can be applied to deform the highly viscous quasi-liquid metal 16.

[0064] In some embodiments, the processing temperature can be reduced to below the crystallization temperature of the quasi-liquid metal 16 before a large amount of crystallization occurs within the quasi-liquid metal 16. In some embodiments, a large amount of crystallization occurring means that 80% of the quasi-liquid metal has crystallized.

[0065] In some embodiments, the processing temperature can be reduced to below the glass transition temperature of the quasi-liquid metal 16 before a large amount of crystallization occurs within the quasi-liquid metal 16.

[0066] In some embodiments, the glass transition temperature of the metallic glass 130 is less than 90% of the lowest melting point of the components to be welded.

[0067] In some embodiments, interfacial amorphization by adding metallic glass can be used to produce a long lap joint or a long butt joint.

[0068] In some embodiments, heating and compression can be applied locally by an integrated tool 132( Figure 18 and Figure 19 ). In some embodiments, heating and compression can be applied locally by separate tools 134, 136( Figure 20 ). In some embodiments, local heating and / or compressive pressure can be applied sequentially from the start to the end of the welding.

[0069] In some embodiments, the tools and methods for creating welds between dissimilar material components can be achieved by the following steps:

[0070] a. Provide a rotary tool 110 that includes at least one shoulder 112, at least one probe member 114 adjacent to the shoulder 112, and at least one positioning strut 120 extending from the probe member 114, wherein the overall terminal end surface of the positioning strut 120 is less than

[0071] 60% of the end surface of the probe member 114;

[0072] b. Penetrate the rotary probe member 114 into the first component 10 and maintain contact of the positioning strut 120 with the surface of the second

[0073] component 12 without significant penetration;

[0074] c. The distance between the probe member 114 and the mating surface of the second component 12 is close enough to create a rapid frictional force at the interface of the first

[0075] component 10 and the second component 12;

[0076] d. The rapid frictional force can be high enough to create

[0077] quasi-liquid metal 16 at the interface of the first component 10 and the second component 12; and

[0078] e. After sufficient quasi-liquid metal 16 has formed at the dissimilar metal interface 14 and before significant crystallization occurs within the quasi-liquid metal 16, the rapid frictional force can be terminated and the processing temperature can be reduced to a temperature below the crystallization temperature of the quasi-liquid metal 16.

[0079] For purposes of illustration and description, the foregoing description of the embodiments has been provided. The foregoing description is not intended to be exhaustive or to limit the disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment but, where applicable, are interchangeable and can be used in the selected embodiment even if not specifically shown or described. Similarly, they can be varied in many ways. Such variations should not be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. A method of joining a first component and a second component, the first component and the second component being made of dissimilar metals, the first component having a lower melting temperature than the second component, the method comprising: Before joining, flatten the mating surface of the second component to a roughness value of Ra < 0.025 μm and reduce the surface oxidation of the second component to a thickness of less than 2 nm; Insert a rotary tool having a shoulder and a rotary probe portion into the first component, the rotary probe portion being spaced 0.05 to 1 mm from the mating surface of the second component; Rotate the rotary tool to generate rapid frictional forces between the second component and the material of the first component that rotates around the one rotary probe portion at the interface of the dissimilar metals, the frictional forces being sufficient to generate a layer of quasi-liquid metal at the interface of the dissimilar metals between the first component and the second component and to generate shear localization within the quasi-liquid metal, the quasi-liquid metal being a metal that is liquid-like at a temperature below the melting points of the first component and the second component, the quasi-liquid metal having a shear strain rate greater than 1×10 4 s -1 ; One distal surface of the rotary probe portion has surface features to facilitate rotation of the near-liquid metal; and After generating the near-liquid metal and before 80% of the near-liquid metal has crystallized, terminate the application of rapid frictional force within 3 seconds and reduce the processing temperature of the near-liquid metal to below the crystallization temperature of the near-liquid metal, thereby joining the first component and the second component along a transition zone having a composition corresponding to the metallic glass former composition.

2. The method according to claim 1, wherein, The distal surface of the rotary tool is concave.

3. The method according to claim 1, wherein, The mating surface of the second component includes grooves.

4. The method according to claim 1, wherein, The application of rapid frictional force between the first component and the second component includes: Providing a rotary tool having at least one shoulder, a rotary probe portion adjacent to the shoulder, and at least one positioning strut extending from the probe portion; and Placing the rotary probe portion into the first component and maintaining contact of the positioning strut with the surface of the second component, the distance between the rotary probe portion and the surface of the second component being sufficient to generate the rapid frictional force between the second component and the material of the first component rotating around the rotary probe portion at the dissimilar metal interface, the rapid frictional force being sufficient to generate near-liquid metal at the dissimilar metal interface.

5. The method according to claim 4, wherein, The at least one positioning strut extending from the probe portion includes an integral end surface, the integral end surface of the at least one positioning strut being less than 60% of the integral end surface of the probe portion.

6. The method according to claim 4, wherein, The at least one positioning strut extending from the probe portion includes at least one positioning strut extending from the distal surface of the probe portion.

7. The method according to claim 4, wherein, The at least one positioning strut extending from the probe portion includes at least one positioning strut in a ring-like shape and extending from the side surface of the probe portion.

8. The method according to claim 1, the method including flattening the mating surface of the second component before applying rapid frictional force.

9. The method according to claim 8, wherein, Flattening the mating surface includes reducing the roughness of the mating surface to less than Ra 1 μm.

10. The method according to claim 1, wherein the method includes reducing an average thickness of surface oxidation on a mating surface of the second component to less than 5 nm before applying a rapid frictional force.

11. The method according to claim 10, wherein, reducing the average thickness of the surface oxidation includes reducing the average thickness of the surface oxidation to less than 2 nm.

12. The method according to claim 1, wherein, applying the rapid frictional force between the first component and the second component includes applying a high-speed frictional force under a compressive pressure by relative movement of the first component and the second component.

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