Patent Description:
Due to differing properties of metals, it may be difficult to bond dissimilar metals using traditional welding methods. Instead, dissimilar metals may be bonded through cladding. However, known methods of cladding may require that a clad layer be of a substantially uniform thickness in order to achieve a bond of sufficient strength and quality. Nevertheless, in certain applications, it may be desirable to have selective portions of the clad layer be thicker than the remainder of the clad layer, for example, to facilitate bonding or coupling between articles, or to increase corrosion, friction, or heat resistance of a specific area of the article.

A method for making clad metal sheets is shown in <CIT> (forming the base for the preamble of claims <NUM> and <NUM>).

Accordingly, it may be desirable to develop a cladded article and method for making a cladded article in which the clad layer may have a varying thickness.

According to a first aspect the invention there is provided a cladded article according to claim <NUM>. The cladded article includes a first metallic layer, a clad layer, and a first solid-state welding interface region positioned between the clad layer and the first metallic layer. The clad layer includes a first clad layer region having a first clad layer thickness in a thickness direction of the clad layer and a second clad layer region having a second clad layer thickness in the thickness direction of the clad layer. The second clad layer thickness may be greater than the first clad layer thickness.

According to a second aspect there is provided a method according to claim <NUM>. The method of manufacturing a cladded article includes providing a first metallic layer comprising a first material and having a first metallic layer surface, providing a clad layer comprising a second material and having a substantially uniform first clad layer thickness, solid-state welding the clad layer to the first metallic layer surface, and, after solid-state welding the clad layer to the first metallic layer surface, creating a modified clad layer region by bonding material to an outer surface of the clad layer opposite the first metallic layer. The second clad layer thickness in the modified clad layer region is larger than the first clad layer thickness.

A more particular description will be rendered by reference to exemplary embodiments that are illustrated in the accompanying figures. Understanding that these drawings depict exemplary embodiments and do not limit the scope of this disclosure, the exemplary embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:.

Various features, aspects, and advantages of the exemplary embodiments will become more apparent from the following detailed description, along with the accompanying drawings in which like numerals represent like components throughout the figures and detailed description. The various described features are not necessarily drawn to scale in the drawings but are drawn to emphasize specific features relevant to some embodiments.

The headings used herein are for organizational purposes only and are not meant to limit the scope of the disclosure or the claims. To facilitate understanding, reference numerals have been used, where possible, to designate like elements common to the figures.

Reference will now be made in detail to various embodiments. Each example is provided by way of explanation and is not meant as a limitation and does not constitute a definition of all possible embodiments.

<FIG> shows a cladded article <NUM> according to the invention. The cladded article <NUM> includes a first metallic layer <NUM> and a clad layer <NUM>. The first metallic layer <NUM> may be formed of a material such as stainless steel, carbon steel, titanium, nickel, aluminum, or alloys including any of these materials. In an exemplary embodiment, the clad layer may be formed of materials such as aluminum, steel, titanium, zirconium, copper, silver, tantalum, or alloys including any of these materials. However, it will be understood that the first metallic layer <NUM> and the clad layer <NUM> are not limited to these materials, and other materials may be used depending on the requirements of the specific application.

The clad layer <NUM> is bonded to the first metallic layer <NUM> through a solid-state welding method, thereby forming a first solid-state welding interface region <NUM> positioned between the clad layer <NUM> and the first metallic layer <NUM>. The first solid-state welding interface region <NUM> is a region between the clad layer <NUM> and the first metallic layer <NUM> where atoms from each of the clad layer <NUM> and the first metallic layer <NUM> are diffused among each other. It will be understood that the illustration of the first solid-state welding interface region <NUM> is for illustration purposes only and is not drawn to scale. In an exemplary embodiment, the first solid-state welding interface region <NUM> may be a first explosion welding interface region, as described in detail below.

As seen in present <FIG>, the clad layer <NUM> may include a first clad layer region <NUM> having a first clad layer thickness D1 in a thickness direction Z of the clad layer <NUM>. In an exemplary embodiment, the first clad layer thickness D1 may range from approximately <NUM> to approximately <NUM> (i.e., approximately <NUM> inches). It may be understood that when the first clad layer thickness D1 becomes substantially larger than <NUM>, it may become difficult to perform solid-state welding between the clad layer <NUM> and the first metallic layer <NUM>. The clad layer <NUM> may further include a second clad layer region <NUM> having a second clad layer thickness D2 in the thickness direction Z of the clad layer <NUM>. The second clad layer thickness D2 may be greater than the first clad layer thickness D1. The second clad layer thickness may be any size to suit the desired application. It will be understood that, in general, a clad layer being formed of a uniform thickness D1 will have a thickness manufacturing tolerance associated with it. For example, if an exemplary embodiment of a clad layer has a desired uniform thickness of <NUM>, the actual produced clad layer may have a thickness in any one spot of <NUM> +/- x, x being the thickness manufacturing tolerance. It will be understood that in the cladded article <NUM>, a difference D3 between the first clad layer thickness D1 and the second clad layer thickness D2 may be greater than the thickness manufacturing tolerance of a clad layer having a uniform thickness equal to D1. In other words, the variation in the thickness of cladded article <NUM> is by design and is not merely a byproduct of manufacturing tolerances.

<FIG> show exemplary embodiments illustrating possible variations in the size and shape of the second clad layer region. For example, in <FIG>, a plurality of identical second clad layer regions <NUM> are provided. However, it will be understood that each second clad layer region <NUM> of the plurality of clad layer regions <NUM> does not need to be identical. For example, <FIG> shows an exemplary embodiment in which the second clad layer regions 124a, 124b, and 124c vary in thickness. <FIG> shows an exemplary embodiment in which lengths and/or widths of second clad layer regions 124d, 124e may be varied. <FIG> shows an exemplary embodiment in which a thickness of the second clad layer region 124f can be varied within the second clad layer region 124f. <FIG> shows exemplary embodiment illustrating that the second clad layer region <NUM> is not limited to a specific shape. For example, the second clad layer region <NUM> may have a curved or circular shape, or the second clad layer region <NUM> may have an irregular polygon shape. In some cases, the second clad layer region <NUM> may require a complex three-dimensional (3D) shape in order to couple or interact with other pieces. <FIG> shows an exemplary embodiment where the second clad layer region 124j may include a through hole <NUM> or a notch <NUM> for mechanically fitting or coupling with other pieces.

The examples above describe that the first metallic layer <NUM> and the clad layer <NUM> are bonded through a solid-state welding method. Solid-state welding may include a group of welding processes producing bonds/welds between structural elements at temperatures below the melting point of the base materials being joined, without the addition of brazing filler metal. Solid-state welding may be described as a bonding/welding process (i) without putting a portion of the structural elements through liquid or vapor phase, (ii) with the use of pressure, and (iii) with or without the aid of temperature. Solid-state welding is done over a wide range of pressure and temperature, with appreciable deformation and solid-state diffusion of the base materials. Solid-state welding processes include cold welding, diffusion welding, explosion welding, forge welding, friction welding, hot pressure welding, roll welding, and ultrasonic welding.

Explosion welding ("EXW") is a solid-state welding technique using controlled detonations to force dissimilar metals into a high-quality, metallurgically bonded joint. The transition joint between the dissimilar metals has high mechanical strength, is ultra-high vacuum tight and can withstand drastic thermal excursions. EXW is a solid-phase process where welding or cladding two metals together is accomplished by accelerating one of the components at extremely high velocity through the use of explosives. The process is solid-phase because both components are, at all times, in a solid state of matter. This may be contrasted with other metal-to-metal welding or cladding techniques such as arc-welding, gas welding, hot-dipping, electroplating and vapor deposition, which require at least one component to be liquified, gasified or ionized.

EXW being a solid-state process, it will typically subject both dissimilar metals to far lower process temperatures than liquid or gas-state processes. The crystalline structure of a metal is highly dependent upon the temperatures to which it has been exposed. For some metals, exposure to high temperature processes can alter the physical characteristics of the metal in very detrimental ways, e.g., rendering the metal too brittle for a given application. EXW is commonly utilized to clad carbon steel plate with a thin layer of corrosion resistant material. For example, stainless steel, nickel alloy, titanium, zirconium, silver, and tantalum are non-limiting examples of materials used for the clad layer <NUM> as shown in <FIG>. It will be understood that the clad layer material <NUM> is not limited to these materials, and other materials may be used as warranted by the particular application. Additionally, other materials aside from carbon steel may be used as the first metallic layer <NUM>.

Typical geometries produced by EXW include plates, tubing, tube sheets and cylinders. While either surface, i.e., inner or outer, of tubing and tube sheets may be the cladder layer, for solid cylinders only the external surface may be the cladder layer, for the readily apparent reason that explosives cannot be disposed in a solid cylinder. While limitations, at least from an efficiency perspective, do exist for initial formation of a geometry by EXW, modifications may be made to the standard geometries. That is, once the clad layer is formed by EXW, the clad plate, clad tube, clad tube sheet or clad cylinder may be subjected to a number of post-cladding processes resulting in numerous different shapes. Essentially any forming/machining process may be applied to the clad structure that will not degrade the clad layer.

EXW can produce a bond between two metals that cannot necessarily be welded or otherwise joined together by conventional means. The process does not melt either metal, instead the surfaces of both metals are plasticized while, simultaneously, coming into intimate contact with each other. The plasticization and contact are sufficient to create a weld. This is a similar principle to other non-fusion welding techniques, such as friction welding. Large areas can be bonded extremely quickly and the weld itself is very clean, due to the fact that the surface material of both metals is violently expelled during the reaction. EXW can join a wide array of similar and dissimilar metals.

<FIG> shows an exemplary embodiment of a method <NUM> for explosively welding a first metallic layer <NUM> and a clad layer <NUM> to generate a cladded article <NUM>. In block <NUM>, the first metallic layer <NUM> and the clad layer <NUM> are separately prepared and inspected. It will be noted that in explosive welding, it may be important for the clad layer <NUM> to have a substantially uniform thickness, otherwise the geometry of forces applied during the explosive welding may be sub-optimal, resulting in a low-quality weld. In block <NUM>, mating surfaces of the metallic layer <NUM> and the clad layer <NUM>, i.e., a metallic layer mating surface <NUM> and a clad layer mating surface <NUM>, may be ground by a grinder <NUM>. In block <NUM>, the clad layer <NUM> may be positioned with the clad layer mating surface <NUM> facing the metallic layer mating surface <NUM> with a predetermined gap <NUM> provided therebetween. Explosive material <NUM> may be layered over the clad layer <NUM>. In block <NUM>, the explosive material <NUM> is detonated starting at a first side and progressing to an opposite side as illustrated by arrow <NUM>. The force of the explosion <NUM> propels the clad layer <NUM> against the metallic layer <NUM> thereby forming the first solid-state welding interface region <NUM> therebetween. In block <NUM>, rollers <NUM> are applied to the cladded article <NUM> to flatten it. In block <NUM>, the cladded article undergoes quality testing. For example, an ultrasonic probe <NUM> may be used over an outer surface <NUM> of the clad layer <NUM> to check for high quality bonds between the clad layer <NUM> and the first metallic layer <NUM>.

While the exemplary embodiment described above has the first metallic layer <NUM> directly bonded to the clad layer <NUM>, it will be understood that in some embodiment, an interlayer may be provided between the first metallic layer <NUM> and the clad layer <NUM>. For example, <FIG> shows an exemplary embodiment of a cladded article <NUM> using an interlayer. The cladded article may include a first metallic layer <NUM>, a second metallic layer <NUM>, and a clad layer <NUM>. The second metallic layer <NUM> may be a base layer, and the first metallic layer <NUM> may be an interlayer. The first metallic layer <NUM> may be formed of material comprising copper, for example. A first metallic layer surface <NUM> of the first metallic layer <NUM> may be bonded to the clad layer <NUM> via a first solid-state welding interface region <NUM>. Additionally, the first metallic layer <NUM> may be bonded to the second metallic layer <NUM> via a second solid-state welding interface region <NUM> on a side opposite the first metallic layer surface <NUM>. In an exemplary embodiment, the first solid-state welding interface region <NUM> and the second solid-state welding interface region <NUM> may be a first explosion welding interface region and a second explosion welding interface region.

The exemplary embodiments described above show the cladded article <NUM> and the cladded article <NUM> as flat plate-like structures. However, it will be understood that any shape or form suitable for cladding, such as pipes, tubes, cylinders, and/or any other suitable shape. For example, <FIG> shows an exemplary embodiment a pipe-form cladded article <NUM> having a first metallic layer <NUM> and a clad layer <NUM>. The first metallic layer <NUM> and the clad layer <NUM> may be bonded together by a first solid-state welding interface region <NUM> positioned between the clad layer <NUM> and the first metallic layer <NUM>. The clad layer <NUM> may have a first clad layer region <NUM> and a second clad layer region <NUM> having a larger thickness than the first clad layer region <NUM>.

<FIG> shows an exemplary embodiment of a pipe-form cladded article <NUM> using an interlayer. For example, the cladded article <NUM> may include a first metallic layer <NUM>, a second metallic layer <NUM>, and a clad layer <NUM>. The first metallic layer <NUM> may be a copper interlayer, for example. The first metallic layer <NUM> and the clad layer <NUM> may be bonded together via a first solid-state welding interface region <NUM>. Additionally, the first metallic layer <NUM> and the second metallic layer <NUM> may be bonded together via a second solid-state welding interface region <NUM>. The clad layer <NUM> may have a first clad layer region <NUM> and second clad layer regions 424a, 424b having larger thicknesses than the first clad layer region <NUM>.

<FIG> show additional exemplary embodiments of cladded articles with varying thickness clad layers. For example, <FIG> shows a cladded article <NUM>, approximately half of which has been subjected to finishing processing. <FIG> further shows a finished clad surface <NUM> and an unfinished clad surface <NUM>. The varying thickness region of the clad layer may take the form of finished side rib <NUM>, unfinished side rib <NUM>, and cross ribs <NUM>.

<FIG> shows an exemplary embodiment of a cladded article <NUM> in which an outer layer <NUM> is a base material, and an inner layer <NUM> is a clad material. Ducts <NUM> may be formed of a same material as the inner layer <NUM> and are built up through the outer layer <NUM>. Holes <NUM> may be preformed in the outer layer <NUM> and the inner layer <NUM>, or may be formed by machining after the formation of the bodies of the ducts <NUM>.

<FIG> shows an exemplary embodiment of a cladded article <NUM> that may be used in construction of a pressure vessel or reaction chamber. The cladded article <NUM> may include a base layer <NUM> and a clad layer <NUM>. The base layer <NUM> and the clad layer <NUM> may be bonded via a solid-state welding interface region <NUM>. The base layer <NUM> may be formed of a material such as stainless steel, carbon steel, titanium, or any other material that may be suitable for forming a pressure vessel. The clad layer <NUM> may be formed of pure tantalum or a tantalum alloy, or another corrosive-resistant material used for a reaction chamber. In an exemplary embodiment, the clad layer <NUM> may be formed of a tantalum alloy comprising <NUM> % tungsten. Materials such as tantalum can be quite expensive, and, accordingly, it is desirable to minimize the use of these materials as much as possible to reduce production costs. On the other hand, when joining the cladded article <NUM> with other cladded articles to form the finished reaction chamber, it may be useful to have thick regions of the clad layer <NUM> in order to provide more material for bonding parts together and creating a higher quality joint. For example, a material like tantalum may have a substantially higher melting point than the underlying base layer <NUM>. Accordingly, heating the clad layer <NUM> for bonding to another cladded article may warp or damage the underlying base layer <NUM>. Accordingly, it may be desirable to have a thicker layer of tantalum where joints are to be made, to better insulate the underlying base layer <NUM> from thermal damage. To address these competing interests, the cladded article <NUM> may include a first clad layer region <NUM> in which the thickness of the clad layer <NUM> is a substantially uniform first thickness. Additionally, the cladded article <NUM> may include a second clad layer region <NUM> that has a second thickness larger than the first thickness. The second clad layer region <NUM> may include an underlying portion <NUM> of the clad layer <NUM> and a clad layer projection <NUM> bonded to the underlying portion <NUM>. In an exemplary embodiment, the second clad layer region <NUM> may be provided in areas where a larger thickness is needed for bonding. Accordingly, production costs can be substantially reduced by only providing the extra material where needed.

The second clad layer region <NUM> may be formed by layering a plurality of foils <NUM>. In other words, the clad layer projection <NUM> may comprise a plurality of layered foils <NUM>. <FIG> shows that the second clad layer region may be formed by layering the foils <NUM><NUM>, <NUM><NUM>,. , <NUM>n-<NUM>, <NUM>n, where n is an integer representing the total number of foils. While <FIG> shows at least four foils <NUM>, it will be understood that more or less than four foils may be used. For example, the second clad layer region <NUM> may comprise a single foil bonded to the clad layer <NUM>. Alternatively, any number of foils greater than four may be used to achieve any desired thickness of the second clad layer region. In an exemplary embodiment, the foils <NUM> may be formed of a similar material as the clad layer <NUM>. For example, the foils <NUM> may be formed from tantalum or a tantalum alloy. Alternatively, in an exemplary embodiment, the foils <NUM> may be formed of different materials. For example, the foils may be arranged in an alternating pattern of Ta, W, Ta, W, etc., or an alternating pattern of Ta, Cu, Ta, Cu, etc..

In an exemplary embodiment, a thickness of each foil <NUM> may be in a range of approximately <NUM> inches (<NUM>) to approximately <NUM> inches (<NUM>). In an exemplary embodiment, a total thickness of the second clad layer region <NUM> may be <NUM> inches (<NUM>) above a surface of the clad layer <NUM>. However, it will be understood that smaller and larger thickness may also be obtained depending on the needs of the desired application.

<FIG> shows an exemplary embodiment of a method <NUM> for manufacturing a cladded article with a clad layer having a varying thickness. For example, in block <NUM>, a first metallic layer is provided, such as the base layer <NUM> shown in <FIG>. In block <NUM> a clad layer is provided, such as clad layer <NUM> show in <FIG>. In block <NUM>, the first metallic layer and the base layer may be bonded together via solid-state welding. The solid-state welding may be an explosive welding process, or any other suitable solid-state welding process as described above. The solid-state welding may be achieved by any of the methods described above. In block <NUM>, a modified clad layer region, such as the second clad layer region <NUM> shown in <FIG>, may be created by bonding material to an outer surface of the clad layer opposite the first metallic layer. In an exemplary embodiment, block <NUM> may include creating a plurality of modified clad layer regions, such as the second clad layer regions 124a, 124b, and 124c shown in <FIG>.

<FIG> shows an exemplary embodiment of a method <NUM> for manufacturing a cladded article with a clad layer having a varying thickness. For example, in block <NUM>, a first metallic layer is provided, such as the base layer <NUM> shown in <FIG>. In block <NUM> a clad layer is provided, such as clad layer <NUM> show in <FIG>. In block <NUM>, the first metallic layer and the base layer may be bonded together via solid-state welding. The solid-state welding may be an explosive welding process, or any other suitable solid-state welding process as described above. The solid-state welding may be achieved by any of the methods described above. In block <NUM>, an incremental amount of material is bonded to an outer surface of the clad layer opposite the first metallic layer to form a modified clad layer region, such as the foil <NUM><NUM> shown in <FIG>. In the case of the foil <NUM><NUM>, the foil <NUM><NUM> may be ultrasonically welded to the clad layer <NUM>. In block <NUM>, it is determined whether the modified clad layer region is at a desired height. If the modified clad layer region is not at the desired height (i.e., "no" at block <NUM>), then the method proceeds to block <NUM>, where an incremental amount of material is bonded to the modified clad layer region, such as the foil <NUM><NUM> shown in <FIG>. In the case of the foil <NUM><NUM>, the foil <NUM><NUM> may be bonded to the foil <NUM><NUM> via ultrasonic welding. The method then returns to block <NUM>. The loop of block <NUM> and <NUM> may be repeated as many times as necessary to achieve the desired height of the modified clad layer region. Once the desired height of the modified clad layer region is obtained, the method may proceed to block <NUM>, where finishing processing may be applied. Finishing processing may include, but is not limited to, processes such as polishing, buffing, machining, etching, etc., to achieve a desired final shape and texture.

In the method <NUM> described above, an ultrasonic welding process is described as one possible method for creating the modified clad layer region. However, it will be understood that a variety of processes may be used to bond material to the clad layer and form the modified clad layer region, including, but not limited to, a powder bed fusion process, a directed energy deposition process, a sheet lamination process, a friction welding process, a friction stir welding process, a cold metal transfer process, a resistance welding process, a kinetic metallization process such as a cold spray deposition process or a warm spray deposition process, a binder jet printing process, a plasma spray process.

A cold spray deposition process may include accelerating a powdered material in a gas jet to collide with a substrate. When colliding with the substrate, particles of the powered material may undergo plastic deformation and adhere to a surface of the substrate. A warm spray deposition process may be similar to the cold spray deposition process, except that the particles of the powered material are heated before collision. The temperature of the particles will be less than the melting point of the powered material in a warm spray deposition process.

Powder bed fusion ("PBF") is a process that may be used with a variety of techniques such as direct metal laser melting, electron beam melting, directed metal laser sintering, selective laser melting, selective laser sintering, and selective heat sintering. PBF begins with a powder and involves melting the powder to a sufficient degree for the particles to fuse together. Particles may be "sintered" (partially melted) or fully melted in a PBF process. Thermal energy in the form of a laser, beams of electrons, or a heated print head partially or fully melt the powder. PBF adds an ultrathin layer of powdered material over the preceding layer of beginning substrate. The layer may be spread by a roller or blade. Powder may be fed from a reservoir beneath or next to a build platform that lowers to accommodate each successive layer of powder. Powder may be fused to the entirety or selected portion of the underlying structure using a laser, electron beam light source, visible light source, or simply a heat source. At the conclusion of the process, the unfused powder may be blown or blasted away.

<FIG> shows an example (not part of the invention) of a powder bed manufacturing system <NUM>. In the system <NUM>, the component <NUM> may be built up layer-by-layer by aiming a laser <NUM> at powder <NUM> via scanner <NUM>. The powder <NUM> may be contained in powder bed <NUM>, and the portion of the powder <NUM> being acted upon by laser <NUM> may disposed on previously solidified portions of component <NUM>. The powder <NUM> may constantly supplied to powder bed <NUM> by powder delivery system <NUM> that may include a powder reservoir 20a and a rake or roller 20b.

<FIG> shows an example (not part of the invention) of a powder feed manufacturing system <NUM>. In the system <NUM>, the component <NUM> may be built up layer-by-layer by aiming a laser <NUM> at powder <NUM> via beam guidance system <NUM> and lens <NUM>. The powder <NUM> may be contained in a powder supply <NUM> and may be directed to proper position by a deposition head <NUM>. A carrier gas <NUM> may convey the powder <NUM> to the proper position on the previously solidified portions of component <NUM>. Laser <NUM> may selectively act upon a portion of the powder <NUM> disposed on previously solidified portions of the component <NUM>. Powder that has not been acted upon by laser <NUM> may be periodically removed from the component, e.g., between layer formations.

Directed energy deposition ("DED") may utilize highly focused thermal energy delivered via laser, electron beam, or plasma arc to melt and fuse material jetted into the heated chamber from either powdered metal or wire filament. DED is sometimes referred to as direct metal deposition or metal deposition. The system may feature metal deposition along four or five axes.

Laser engineered net shape technology is a DED based system that dispenses powder from nozzles and selectively melts portions of powder by a laser to build an object. In other words, DED may be used for adding material to existing metal components or metal base materials, such as a clad layer in a cladded article. Other DED based processes may include electron beam additive melting and rapid plasma deposition. In electron beam additive melting, metal melting may occur via an electron beam firing in a vacuum chamber. Either metal powder or wire filament may be fully melted in layers as thin as <NUM> microns each. In rapid plasma deposition, a plasma arc may melt a wire filament in an argon gas environment to produce parts that may require little or no post-production machining.

<FIG> shows an example (not part of the invention) of an electron beam DED apparatus <NUM>. Apparatus <NUM> may include an electron beam ("EB") gun <NUM>, a three-axis manipulator, an electron beam <NUM> source and a wire feeder <NUM>. Exemplary embodiments may integrate electron beam gun <NUM> and wire feeder <NUM>, as seen in <FIG>. The three-axis manipulator may allow relative movement of the working tip <NUM> of wire <NUM> to the workpiece <NUM> in three dimensions, i.e., three axes. The embodiment of <FIG> may include a workpiece platform <NUM> to enable relative movement along the x-axis. Side-to-side movement and up-down movement of the electron beam gun <NUM> may enable relative movement along, respectively, the y-axis and z-axis.

Electrically powered electron beam gun <NUM> may produce a directed beam <NUM> of high velocity electrons. This directed beam <NUM> may intersect the working tip <NUM> of wire <NUM> and, optionally, either the workpiece <NUM> or the molten alloy puddle <NUM> that is melted metal from wire <NUM> but also, possibly, from workpiece <NUM>. Kinetic energy from the electrons may be transformed into heat upon impact with one or more of the working tip <NUM> of the wire <NUM>, a substrate <NUM>, the workpiece <NUM> and the molten puddle <NUM>. The heat developed may be sufficient to melt the solid wire <NUM>. As the workpiece platform <NUM> and the attached workpiece <NUM> are moved laterally (to the left as shown in <FIG>), the molten alloy that is no longer being heated by the electron beam <NUM> is able to cool and, thus, become a re-solidified alloy <NUM>, which is now part of the workpiece <NUM>. Continuous advancement of the wire <NUM> by the wire feeder <NUM> in conjunction with movement of the platform <NUM> maintains the molten alloy puddle <NUM> at a relatively constant size at a steady working state. The volumetric characteristics of what the re-solidified alloy <NUM> 'adds' to the workpiece with each layer of metal added will depend on the amount of energy added to the solid wire <NUM> and the molten alloy puddle <NUM>, the movement of the workpiece <NUM>, the cooling parameters of the system and the rate at which the wire <NUM> exits the wire feeder <NUM>. Modifying these and other parameters allows for varying thickness of the re-solidified alloy <NUM> layer on top of a prior deposit <NUM>. The width, i.e., y-axis dimension, of the re-solidified alloy <NUM> may also be variable to at least some extent.

The system <NUM> may be performed under vacuum conditions to prevent dissipation of the electron beam <NUM> and heating of the air between the electron beam gun <NUM> and the wire <NUM>.

<FIG> shows an example (not part of the invention) of a wire arc manufacturing apparatus <NUM>. In apparatus <NUM>, an electrical potential is applied to the wire <NUM> though the electrically conducting element <NUM> and the wire dispensing rollers <NUM>. The electrical potential of the workpiece <NUM> may be significantly different from that of the wire <NUM>; e.g., one may be charged and the other electrically grounded. The working tip <NUM> of the wire <NUM> may be held a distance from the workpiece <NUM> such that an electric arc <NUM> exists between the working tip <NUM> and the workpiece <NUM>.

The plasma making up electric arc <NUM> may be hot enough to melt the working tip <NUM> of wire <NUM> as well as the portion of the workpiece <NUM> in contact with the plasma. A weld pool <NUM> may be formed on the workpiece <NUM> where the electric arc <NUM>, i.e., plasma, touches the workpiece <NUM> and melted metal from the working tip <NUM> may be added to the weld pool <NUM>. As a three-axis manipulator workpiece platform underlying the substrate <NUM> and the workpiece <NUM> is moved to the left, the weld pool <NUM> moves to the right and the portion of the workpiece <NUM> that had been exposed to the arc <NUM> is able to cool and, thus, become re-solidified alloy <NUM>, which becomes part of the workpiece <NUM>.

A nozzle <NUM> may be associated with a portion of the wire <NUM>. The nozzle <NUM> may supply a shielding gas <NUM> to the welding area. The shielding gas <NUM> may be an inert or semi-inert gas used to reduce the concentration of oxygen and water vapor from the weld area; oxygen and/or water vapor may have detrimental effects upon arc welding results. Accordingly, apparatus <NUM> may alternatively be used under controlled atmospheric conditions including exclusion of oxygen and water vapor. In such a set-up, the nozzle <NUM> and the shielding gas <NUM> may not be necessary.

Continuous advancement of the wire <NUM> through the rollers <NUM> may maintain the weld pool <NUM> at a relatively constant size at a steady working state. The volumetric characteristics of what the re-solidified alloy <NUM> 'adds' to the workpiece <NUM> with each layer of metal added may depend on the arc welding characteristics of the system, such as the difference in electrical potential between the wire <NUM> and the workpiece <NUM>, the x-axis movement of the workpiece <NUM>, the cooling parameters of the system, and the rate at which the wire <NUM> is consumed. Modifying these and other parameters may allow for varying thickness of the re-solidified alloy <NUM> layer on top of the prior deposit <NUM>. The width, i.e., y-axis dimension, of the re-solidified alloy <NUM> may also be variable to at least some extent.

Material jetting is a manufacturing process that uses drop-on-demand technology. Nozzles may dispense droplets of a material, layer by layer. In an example (not part of the invention), UV light may cure and/or harden the droplets before the next layer is created. Alternatively, in an exemplary embodiment such as nanoparticle jetting, liquids may be infused with metal particles. As each layer of droplets is deposited onto the substrate, high temperatures in the build chamber may cause the liquid to evaporate, leaving the layer of metal behind.

A binder jetting process may employ powdered material and a binding agent. Nozzles may deposit droplets of a binder on a layer of powdered metal. Multiple layers result from the powder bed moving downward after each layer is created. It will be understood that the resulting structure may have a higher porosity than other manufacturing methods.

Claim 1:
A cladded article (<NUM>) comprising:
a first metallic layer (<NUM>);
a clad layer (<NUM>), the clad layer (<NUM>) comprising:
a first clad layer region (<NUM>) having a first clad layer thickness (D1) in a thickness direction of the clad layer (<NUM>); and
a second clad layer region (<NUM>) having a second clad layer thickness (D2) in the thickness direction of the clad layer (<NUM>); wherein
the second clad layer thickness (D2) is greater than the first clad layer thickness (D1); and
a first solid-state welding interface region (<NUM>) positioned between the clad layer (<NUM>) and the first metallic layer (<NUM>);
characterized in that the second clad layer region (<NUM>) comprises a plurality of foils (<NUM>) layered on the clad layer (<NUM>); and
a foil of the plurality of foils (<NUM>) is formed of a material comprising tantalum or a tantalum alloy.