Patent Publication Number: US-2022228267-A1

Title: Multi-component deposits

Description:
This application is a divisional of U.S. application Ser. No. 16/657,854, filed Oct. 18, 2019, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The disclosure relates to multi-component deposits and techniques for forming multi-component deposits. 
     BACKGROUND 
     Heat treatment processes may be used to alter the physical properties of a component, such as a mechanical part, after the component has been formed. In a typical heat treatment process, a fabricated component may be heated to a predefined bulk temperature, such as a transformation temperature of the constituent material of the component, held at the temperature for a period of time to achieve a relatively uniform temperature throughout the component, and cooled at a predefined cooling rate to achieve a particular transformation of the constituent material of the component. As a result, the component may include a relatively uniform set of physical properties different from the initial set of physical properties of the component prior to heat treatment. 
     SUMMARY 
     The disclosure describes example articles, and techniques and systems for forming the example articles, that include a deposit having a heat-treated component and either a non-heat-treated or a differently-heat-treated component. 
     In some examples, the disclosure describes an example technique that includes cold spraying first particles and second particles of a metal alloy on at least a portion of a surface of a substrate to form a deposit on the surface of the substrate. The first and second particles have been subjected to different heat treatments prior to cold spraying. For example, the first particles may include particles that have undergone a heat treatment, while the second particles may include particles that have either undergone no heat treatment or undergone a different heat treatment than the first particles. Cold spraying involves accelerating the first particles and the second particles toward the surface of the substrate without melting or creating other thermally induced changes to a microstructure of the first and second particles. As a result, the first particles form a first, heat-treated component and the second particles form a second non-heat-treated or differently-heat-treated component, and the particles and substrate are not subject to a heat treatment during the cold spray process that may further modify their thermomechanical properties. 
     In some examples, the disclosure describes an example article that includes a substrate defining a surface and a deposit on the surface of the substrate in which the deposit was formed using cold spraying. The deposit includes a first component and a second component. Cold spraying involves accelerating first particles and second particles of a metal alloy toward the surface of the substrate without creating thermally induced changes to a microstructure of the respective first and second particles. The first and second particles have been subjected to different heat treatments prior to cold spraying. 
     The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a conceptual cross-sectional view of an example article including a deposit that includes a first component and a second component. 
         FIG. 1B  is a conceptual cross-sectional view of an example article including a deposit that includes a first component and a second component. 
         FIG. 2  is a conceptual and schematic block diagram of an example system for forming a deposit on a surface of a substrate by cold spraying first particles and second particles of a metal alloy on the surface of the substrate. 
         FIG. 3  is a flow diagram illustrating an example technique for forming a deposit on a surface of a substrate by cold spraying first particles and second particles of a metal alloy on the surface of the substrate. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure generally describes example systems and techniques for depositing heat treated metal alloys and, optionally, non-heat-treated metal alloys onto a substrate without exposing the substrate to high temperatures. The example techniques involve cold spraying metal alloy particles onto a substrate to form a deposit. These cold sprayed metal alloy particles include a mix of particles having a metal alloy that has been heat treated (“heat-treated particles”) and particles having the same metal alloy that either has not been heat treated (“non-heat-treated particles”) or has been heat treated with a different heat-treatment (“differently-heat-treated particles”). Heat-treated particles may have properties, such as tensile strength and elongation, that are improved compared to non-heat-treated particles of the same composition. In cold spraying, the heat-treated particles, non-heat-treated particles, and/or differently-heat-treated particles are directed toward and impact the substrate while having temperatures that remain below a temperature at which the particles experience thermally induced property changes. The cold sprayed particles bond with previously deposited particles to form a two-component deposit that includes a heat-treated component and either a non-heat-treated component or a differently-heat-treated component. 
     In some examples, the techniques discussed herein incorporate heat-treated materials into an article without exposing an underlying substrate of the article or materials in the deposit to temperature conditions experienced during heat treatment processes. For example, deposition of a heat-treated metal alloy layer may involve first depositing the metal alloy layer and subsequently exposing both the metal alloy layer and the substrate to heat treatment conditions, including high temperature conditions for extended periods of time and/or fast cooling conditions. These high temperature and/or fast cooling conditions may damage the substrate and/or produce undesired changes in properties of the substrate. Cold spray deposition of heat-treated particles may occur below the melting point or other transition temperature of the metal alloy and without bulk heating of the underlying substrate or deposited material, such that the underlying substrate or deposited material is exposed to lower temperatures than techniques that incorporate heat-treated materials onto a substrate without cold spraying. As such, properties of the heat-treated particles, non-heat-treated particles, and/or differently-heat-treated particles may be substantially unchanged after cold spraying. 
     In some examples, the techniques discussed herein incorporate a blend of various heat-treated materials and non-heat-treated materials into an article. For example, heat treatment of a metal alloy layer may involve bulk heating the metal alloy layer to a substantially uniform temperature to produce a metal alloy layer with substantially homogeneous properties. Cold spray deposition of the heat-treated particles and differently-heat-treated or non-heat-treated particles may produce a deposit that includes properties, such as tensile strength and elongation, derived from the heat-treated material, and either and the non-heat-treated material or the differently-heat-treated material, such that deposits formed from a mix of heat-treated particles and differently-heat-treated or non-heat-treated particles may include a greater variety of properties than deposits formed from heat-treated or non-heat-treated materials alone. 
       FIG. 1A  is a conceptual cross-sectional view of an example article  10 A that includes a substrate  12  and a deposit  14 . In some examples, article  10 A may be a component of a gas turbine engine. For example, article  10 A may be a component with a barrier coating, a repaired component, a multi-layer component, or the like. Due to high temperatures experienced in gas turbine engine, components of gas turbine engines may incorporate heat treated materials to relieve residual stresses and increase desired properties. In some examples, substrate  12  includes a bulk material, such as a forged metal, a cast metal, or a sheet metal, that may be substantially homogeneous (e.g., homogeneous or nearly homogeneous to the extent possible by common metallurgy techniques). Bulk materials that may be used for substrate  12  include, but are not limited to, Ni-based alloys, Co-based alloys, Ti-based alloys, or Fe-based alloys. Substrate  12  defines a surface  16 . Surface  16  may have a variety of surface conditions including, but not limited to, an as-manufactured surface, a damaged surface, or the like. 
     Deposit  14  is on at least a portion of surface  16  of substrate  12 . While shown in  FIG. 1A  as covering an entirety of surface  16 , in some instances, deposit  14  may only cover a particular area, such as a portion of article  10 A that may experience abrasion, high temperatures, or other external phenomena that induce stresses and/or fractures. Deposit  14  may represent a one or more of a variety of functional deposits of the metal alloy on substrate  12  including, but not limited to: a structure functionally differentiated from substrate  12 , such as a flange or other structure extending from and/or complementary to substrate  12 ; a repair joint of substrate  12 , such as a filler; a coating on substrate  12 , such as a barrier coating; a layer on substrate  12 , such as a layer in a multi-layer part; or the like. 
     In some examples, deposit  14  may be configured to improve properties of substrate  12 . For example, substrate  12  may be a damaged component having cracked surface  16  that includes one or more cracks that extend into substrate  12 . Rather than replace substrate  12  with a new part or repair substrate  12  using high temperature techniques, such as welding or post-deposition heat treatment, deposit  14  may be formed within the one or more cracks to fill the cracks. As a result, substrate  12  may have improved properties, such as strength aerodynamic shape, or the like, compared to substrate  12  prior to receiving deposit  14 . In some examples, deposit  14  and substrate  12  include the same composition, such that article  10 A may have a substantially homogeneous composition after repair of substrate  12 . In some examples, deposit  14  and substrate  12  may include different compositions. For example, a particular composition of deposit  14  may be better suited (e.g., more easily bond with substrate  12  using cold spraying, etc.) as a filler for cracks than a composition of substrate  12 . 
     In some examples, deposit  14  may be configured to protect substrate  12  from physical impact or chemical reactants. For example, substrate  12  may be a high temperature component, such that portions of substrate  12  near surface  16  may face a high temperature environment with reducing agents, such as calcia-magnesia-alumina-sulfur (CMAS), that may damage substrate  12 . To protect substrate  12  from these agents, deposit  14  may extend continuously across surface  16  to provide a dense, high strength barrier for substrate  12 . 
     In some examples, deposit  14  may be configured to complement substrate  12  as a separate structure that provides additional functionality to substrate  12 . For example, deposit  14  may include a mechanical component, such as a flange, that is mechanically coupled to substrate  12  and configured to perform a different function than substrate  12 . 
     Deposit  14  includes a metal alloy. Metal alloys may have constituent elements that, when subjected to various heat treatments, undergo phase transformations or migrate from solution to change a microstructure of deposit  14 . The metal alloy of deposit  14  may include any metal alloy whose properties may change, such as through changes in microstructure or homogeneity of the metal alloy, in response to heat treatment processes. Metal alloys that may be used include, but are not limited to, Mg-based alloys, Ni-based alloys, Ti-based alloys, Fe-based alloys, Al-based alloys, Co-based alloys, Ta-based alloys, Nb-based alloys, Zn-based alloys, Cr-based alloys, and Cu-based alloys. 
     Deposit  14  is deposited on surface  16  using cold spraying techniques. As will be explained further in  FIG. 2  below, cold spraying involves accelerating first particles (e.g., heat-treated particles) and second particles (e.g., differently-heat-treated or non-heat-treated particles) of the metal alloy constituting at least a portion of deposit  14  toward surface  16  of substrate  12 . Upon impacting surface  16  or a working surface of deposit  14 , the first and second particles undergo deformation and bond to substrate  12  and/or previously deposited particles without melting. As a result of cold spray deposition of the first and second particles, deposit  14  may have a very dense microstructure and an interface with substrate  12  that is substantially free of voids, and may be characterized by grain boundaries and dislocation networks formed at interfaces of localized deposits corresponding to deposited first and second particles. Deposit  14  formed from the first and second particles may have the same or nearly the same microstructure as the first and second particles before spraying, i.e., there is no thermally induced microstructure change to the particles themselves. This may allow better control of the properties of the particles/domains/regions in the deposit compared to cases where melting occurs during spraying. 
     Deposit  14  includes a first component  18  (e.g., a heat-treated component) and a second component  20  (e.g., a differently-heat-treated or non-heat-treated component). While shown as visually differentiated elements (e.g., interfaces between deposits) in  FIG. 1A  to emphasize a relationship of first component  18  and second component  20  to first particles and second particles, respectively, it will be understood that deposits of heat-treated metal alloys corresponding to first component  18  and non-heat-treated or differently-heat-treated metal alloys corresponding to second component  20  may not be differentiated by clear physical boundaries due to bonding of the metal alloy deposits from the particles, and that portions of deposit  14  corresponding to first component  18  and second component  20  may be differentiated by any differences in properties derived from heat treatment processes of the metal alloy, as will be described further below. 
     First component  18  may include any portion of deposit  14  that includes a metal alloy that has undergone heat treatment prior to deposition on surface  16 . Heat treatment may include any process that involves application of heat or cold to a bulk material to change properties of the bulk material. First component  18  may include a heat-treated metal alloy formed from a variety of heat treatments including, but not limited to, annealing, hardening (e.g., aging), surface hardening, and the like. Mechanical properties of first component  18  may depend on a composition of first component  18 , a type of heat treatment previously applied to first component  18 , and/or various parameters used to cold spray heat-treated particles of the metal alloy on surface  16 . 
     Second component  20  may include any portion of deposit  14  that includes a metal alloy that has been subjected to a different heat treatment than first component  18 , such as no heat treatment or another heat treatment. While second component  20  may have a same composition (i.e., same chemistry) as first component  18 , second component  20  may have properties that are different from, and may be complementary to, first component  18 . In some examples, second component  20  includes a metal alloy that has not undergone or been subjected to heat treatment. For example, second component  20  may include a metal alloy that has not undergone an amount (e.g., high enough temperature, long enough period of time) of bulk heating or cooling sufficient to cause a change in microstructure or homogeneity of the metal alloy. In some examples, second component  20  includes a metal alloy that has undergone or been subjected to a different heat treatment than first component  18 . In some examples, the second component may include a heat-treated composition having a same chemistry and different heat treatment as first component  18 . For example, second component  20  may include a metal alloy that has undergone a heat treatment that has caused different changes in microstructure or homogeneity of the metal alloy than the heat treatment of first component  18 . Certain heat treatments directed toward creating more homogeneous microstructures, such as annealing, may complement heat-treatments directed toward precipitating constituents, such as hardening, such that deposit  14  may have a blend of properties that result from more than one heat-treatment. First component  18  may include a heat-treated metal alloy formed from a variety of heat treatments including, but not limited to, annealing, hardening (e.g., aging), surface hardening, and the like. 
     First component  18  and/or second component  20  may be selected for a variety of properties including, but not limited to, tensile strength, yield strength, hardness, toughness, percent elongation, percent reduction, Young&#39;s modulus, and the like. For example, the composition of the metal alloy of first component  18  and second component  20  and/or the heat treatment process corresponding to first component  18  may be selected for any properties of either of the heat-treated metal alloy and/or the non-heat-treated metal alloy. As one example in which deposit  14  is a barrier coating, first component  18  may be selected for high hardness. As another example in which deposit  14  is a repair joint, first component  18  may be selected for high ductility/elongation, high toughness, and/or high tensile strength. Properties of first component  18  and second component  20 , such as tensile strength, elongation, and yield strength, may be measured using test methods such as, for example, ASTM E8 Standard Test Methods for Tension Testing of Metallic Materials, such as for samples that include first component  18  and/or second component  20 , individually or as a blended cold-spray deposit. 
     In some examples, first component  18  includes a hardened metal alloy formed from a hardening process. For example, hardening may increase tensile strength and ductility (i.e., elongation) of the metal alloy, such that deposit  14  that includes first component  18  may have a greater toughness than deposits that do not include a hardened component; reduce hardness of the metal alloy; create a more stable metal alloy that may age less in service; and/or modify surface properties of the first particles that form first component  18 , which may change behaviors of the metal alloy within the bulk of deposit  14 . In some examples, first component  18  includes at least one of a precipitation hardened metal alloy, a quenched hardened metal alloy, or a tempered metal alloy. In some examples, a tensile strength of first component  18  is at least about twice as high as a tensile strength of second component  20 , such as at least about 5 times higher. For example, hardened aluminum may have a tensile strength of about 20,000 PSI or higher, while non-hardened aluminum may have a tensile strength of about 4000 PSI. In some examples, a percent elongation of first component  18  is at least about 50% higher than a percent elongation of second component  20 . For example, hardened aluminum may have a percent elongation of about 4-8%, while a non-hardened aluminum may have a percent elongation of about 2-4%. 
     As a result of incorporation of both first component  18  and second component  20 , deposit  14  may have bulk properties derived from first component  18  and second component  20  that are different from properties of first component  18  or second component  20  individually. For example, while first component  18  may have improved properties such as tensile strength and ductility as compared to second component  20 , first component  18  may have increased brittleness, which may increase susceptibility to cracking. However, second component  20  may moderate these properties, such that deposit  14  may have values of bulk properties that are between the individual properties of either first component  18  or second component  20 . A volume ratio of first component  18  and second component  20  may be selected to achieve a particular set of properties derived from a relative volume of first component  18  and a volume of second component  20 . In some examples, a volume percentage of first component  18  in deposit  14  is between about 1% and about 99%, such as between about 10% and about 90%, or between about 30% and about 70%. 
     First component  18  and second component  20  may be distributed throughout deposit  14  in various concentrations and distributions. For example, due to incremental deposition of first and second particles during cold spraying, distribution (e.g., parallel or normal to surface  16  of substrate  12 ) of first component  18  and second component  20  may be adjusted temporally and/or spatially. In some examples, first component  18  and second component  20  may be distributed substantially homogenously throughout deposit  14 , such that deposit  14  may have relatively uniform bulk properties. In some examples, first component  18  and second component  20  may be non-homogeneously distributed throughout deposit  14 , such that deposit  14  may have non-uniform bulk properties. For example, a concentration of first component  18  may be higher in a first portion of deposit  14 , such as near surface  16 , than a second portion of deposit  14  to provide properties that may be more suitable for the corresponding portion. 
     In some examples, in addition to incorporating the metal alloy of first component  18  and second component  20 , deposit  14  may include other components that provide alternative or additional functionality to deposit  14 . For example, deposit  14  may include the metal alloy as a first composition and may include another composition, such as another metal, metal alloy, or ceramic, as a third component. For example, the second composition may include various properties that complement first component  18  and/or second component  20 . 
     In the example of  FIG. 1A , regions of deposit  14  corresponding to first component  18  and second component  20  are illustrated as having a similar size. For example, a substantially uniform size may correspond to more uniform grain boundaries. However, in some examples, regions of deposit  14  corresponding to first component  18  and second component  20  may have different sizes.  FIG. 1B  is a conceptual cross-sectional view of an example article  10 B including a deposit that includes a first component and a second component. As illustrated in  FIG. 1B , deposits corresponding to first component  18  and second component  20  may have different sizes. Such different sized deposits of first component  18  and second component  20  may result from different sized first and second particles. In some instances, different size particles may change a behavior of deposit  14  under load. For example, without being limited to any particular theory, second component  20  may have smaller deposits of first component  18  at an interface of deposits of second component  20  and first component  18  boundary. These different sizes of the deposits may impact deformation at the boundaries when under load, such that the smaller deposits may lock the boundary and reduce deformation at the boundary. 
     Articles described herein may be produced using cold spray deposition systems.  FIG. 2  is a conceptual and schematic block diagram of an example system  30  for forming deposit  14  using cold spraying. System  30  is configured to form deposit  14  on substrate  12  by cold spraying first particles and second particles of a metal alloy on at least a portion of surface  16  of substrate  12 . System  30  may include an enclosure  42 , which encloses a stage  44 , a cold spray gun  32 , a first material source  34 , a second material source  36 , and a gas source  38 . System  30  may further include a computing device  40 , which is communicatively connected to stage  44 , cold spray gun  32 , first material source  34 , second material source  36 , and gas source  38 . 
     Article  10  is positioned within enclosure  42 . Enclosure  42  may substantially enclose (e.g., enclose or nearly enclose) stage  44 , cold spray gun  32 , first material feed  34 , second material feed  36 , gas source  38 , and article  10 . Enclosure  42  may maintain a desired atmosphere (e.g., an atmosphere that is substantially inert to the materials from which deposit  14  is formed) around substrate  12  and deposit  14  during the cold spray technique. In some examples, stage  44  may be configured to selectively position and restrain article  10  in place relative to stage  44  during formation of deposit  14 . In some examples, stage  44  is movable relative to cold spray gun  32 . For example, stage  44  may be translatable and/or rotatable along at least one axis to position article  10  relative to cold spray gun  32 . Similarly, in some examples, cold spray gun  32  may be movable relative to stage  44  to position cold spray gun  32  relative to article  10 . In some examples, system  30  may not include enclosure  42  and stage  44 . For example, system  30  may include a portable device configured to cold spray the heat-treated and non-heat-treated metal alloy particles in situ, such as during a repair. In such examples, system  30  may include temporary containment as enclosure  42 . 
     First material source  34  and second material source  36  may each be configured to supply first particles and second particles, respectively, to cold spray gun  32 . Each material source  34  and  36  may include, for example, a hopper or other container containing first particles and second particles, respectively. In some examples, material sources  34  and  36  may each include a pneumatic hopper operatively coupled to gas source  38 , such that gas source  38  enables material sources  34  and  36  to feed the first particles and second particles, respectively, to cold spray gun  32 . Computing device  40  may be communicatively coupled to first material source  34  and second material source  36  to control a rate of flow of first particles and second particles, respectively, from material sources  34  and  36  to cold spray gun  32  via a material feed. For example, computing device  40  may control a valve or a feeder system of the material feed. In addition to first material source  34  and second material source  36 , system  30  may include other material sources, such as for a second composition. While shown as separate equipment, in some examples, first material source  34  and second material source  36  may be the same equipment. For example, first particles and second particles may be pre-mixed prior to being fed into cold spray gun  32 . 
     The first particles and second particles may have properties corresponding to localized properties of first component  18  and second component  20 , respectively, of deposit  14 , as described in  FIG. 1A  above. For example, the first particles may be selected to provide deposit  14  with particular properties resulting from a particular heat treatment including, but not limited to, tensile strength, yield strength, hardness, toughness, percent elongation, percent reduction, Young&#39;s modulus, and the like. In some examples, the first particles include at least one of a precipitation hardened metal alloy, a quenched hardened metal alloy, or a tempered metal alloy. In some examples, a tensile strength of the first particles is at least about 10% greater than a tensile strength of the second particles. In some examples, a percent elongation of the first particles is at least about 10% greater than a percent elongation of the second particles. 
     The first particles and second particles may include any suitable particle size. For example, the size range of the first and second particles may be between about 1 micrometer (μm) and about 50 μm, such as between about 5 μm and about 20 μm. The size range of the first and second particles may be selected to achieve a selected impact velocity, e.g., a velocity of the particles when impacting surface  16 . In some examples, an average size of the first particles and the second particles may be different. 
     Gas source  38  may be configured to accelerate the first and second particles from first material source  34  and second material source  36 , respectively. Gas source  38  may include, for example, a source of helium, nitrogen, argon, or other substantially inert gas, which may function as carrier of the particles. Gas source  38  may be fluidically coupled to a gas feed, which may control a flow rate and/or pressure of gas delivered to cold spray gun  32 . In some examples, the gas feed may include a heater to heat the gas. The pressure of the gas in gas source  38  may be sufficient to achieve supersonic velocities of the gas and/or particles at the outlet of a nozzle. In some examples, the pressure of the gas may be between about 0.1 megapascals (MPa) and about 2 MPa, such as between about 0.5 MPa and about 1.5 MPa. In some examples, the supersonic velocities may be between about 500 meters per second (m/s) to about 1000 m/s. 
     Cold spray gun  32  may be configured to entrain the first particles from first material source  34  and the second particles from second material source  36  in the flow of gas from gas source  38  through a nozzle. The nozzle may accelerate the gas and plurality of particles to high velocities. The resultant high velocity particle stream  48  may be directed toward surface  16  of substrate  12 . Without limiting the description to a specific theory, the high velocity of the plurality of particles may be sufficient to cause plastic deformation of the particles upon impact with surface  16  of substrate  12 . This process may be repeated as particles attach to surface  16  and/or other attached particles defining a build surface  46  of deposit  14 . 
     System  30  may be configured to control relative movement of high velocity particle stream  48  with respect to surface  16  of substrate  12  and/or build surface  46 . For example, directing high velocity particle stream  48  toward substrate  12  may result in deposition of the plurality of particles on surface  16  of substrate  12  and/or build surface  46 . As illustrated in  FIG. 2 , the first particles and the second particles may accumulate to form deposit  14 . For example, high velocity particle stream  48  may be moved over surface  16  and/or build surface  46  until a sufficient amount of the heat-treated metal alloy and the non-heat-treated metal alloy has accumulated to define, at least roughly, deposit  14 . For example, excess metal alloy may be deposited to form a structure with larger dimensions than a final structure of deposit  14 , then excess metal alloy may be machined away to define deposit  14 . Although not illustrated in  FIG. 2 , system  30  may also include a milling device or machining device configured to remove deposited metal alloy to define a final shape of deposit  14 . 
     Computing device  40  may include, for example, a desktop computer, a laptop computer, a tablet, a workstation, a server, a mainframe, a cloud computing system, or the like. Computing device  40  may include or may be one or more processors or processing circuitry, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor,” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some examples, the functionality of computing device  40  may be provided within dedicated hardware and/or software modules. 
     Computing device  40  is configured to control operation of system  30 , including, for example, stage  44 , cold spray gun  32 , material sources  34  and  36 , and/or gas source  38 . Computing device  40  may be configured to control operation of stage  44  and/or cold spray gun  32  to position article  10  relative to cold spray gun  32 . For example, as described above, computing device  40  may control stage  44  and/or cold spray gun  32  to translate and/or rotate along at least one axis to position article  10  relative to cold spray gun  32 . 
     Computing device  40  may control at least one of the feed rate of the first particles from first material source  34 , second particles from second material source  36 , pressure from gas source  38 , flow rate of the gas from gas source  38 , the movement of high velocity particle stream  48  relative to article  10 , a distance between cold spray gun  32  and build surface  46 , the angle of the high velocity particle stream relative to build surface  46 , and a width of overlap between adjacent passes of the high velocity particle stream and the velocity of cold spray gun  32  relative to build surface  46 . Computing device  40  may control at least one of these parameters to control an amount of material, such as heat-treated metal alloy and non-heat-treated metal alloy, added to article  10  at a given time and location and/or to control metallurgical properties of the added material. In some examples, cold spray gun  32  may be scanned (e.g., translated) relative to deposit  14 , and deposit  14  will include a general shape corresponding to the scanned path. 
     The articles described herein may be formed using any suitable technique.  FIG. 3  is a flow diagram illustrating an example technique for forming deposit  14  on surface  16  of substrate  12  that includes cold spraying first particles and second particles of a metal alloy. The technique of  FIG. 3  will be described with concurrent reference to article  10  of  FIG. 1A  and system  30  of  FIG. 2 . In other examples, other systems may be used to perform the technique of  FIG. 3 , the technique of  FIG. 3  may be used to form other composite components, or both. 
     In some examples, the technique illustrated in  FIG. 3  may optionally include preparing substrate  12  ( 50 ). Preparing substrate  12  may include any process or series of processes to prepare surface  16  of substrate  12  for deposition of deposit  14 . In some examples, preparing substrate  12  may include forming substrate  12 . For example, forming substrate  12  may include forging, casting, or performing other metallurgy techniques to define a shape of substrate  12 . In some examples, preparing substrate  12  may include surface preparation of surface  16 , such as, for example, abrading surface  16  and/or coating surface  16  with a coating configured to improve bonding of deposit  14  or to improve mechanical properties or chemical properties of article  10 , such as one or more thermal barrier coatings or environmental barrier coatings. In some examples, preparing substrate  12  may include treatment of a crack, chip, discontinuity, or other damaged feature for repair by deposit  14 . For example, one or more surfaces of a crack may be smoothed, roughened, or otherwise treated to improve deposition or bonding of deposit  14  to the surface of the crack. 
     In some examples, the technique illustrated in  FIG. 3  may optionally include selecting, by system  30 , a composition of heat-treated particles and non-heat-treated particles ( 52 ). The composition of first particles and second particles in high velocity particle stream  48  may include a relative composition (e.g., a ratio) of the first and second particles. In some examples, computing device  40  may hold constant the composition of the first particles and second particles throughout the cold spray deposition process, such as for a deposit having substantially homogenous properties, while in other examples, computing device  40  may vary the composition of the first particles and the second particles during the cold spray deposition process, such as for a deposit having a spatially varying composition. For example, computing device  40  may receive, such as from a user input, a desired composition of deposit  14 . The desired composition may represent a relative composition of first component  18 , second component  20 , and/or any other composition in resulting article  10 . 
     The technique illustrated in  FIG. 3  includes cold spraying, by system  30 , heat-treated particles and non-heat-treated particles on to at least a portion of surface  16  of substrate  12  ( 54 ). As discussed above in reference to  FIG. 1A , cold spraying involves using cold spray gun  32  and gas source  38  to accelerate first particles from first material source  34  and second particles from second material source  36  toward surface  16  of substrate  12  without melting the first and second particles. The first and second particles may contact surface  16  at velocities sufficient to cause plastic deformation of the particles and result in attachment or bonding of the particles to surface  16  and/or other attached particles defining build surface  46 . In some examples, cold spraying includes high pressure cold spraying. For example, gas source  38  and material sources  34  and  36  may include pressurization systems to pressurize each of gases, first particles, and second particles. 
     In some examples, the technique illustrated in  FIG. 3  may optionally include, after cold spraying the first and second particles to form first component  18  and second component  20 , machining the deposited first component  18  and second component  20  to define deposit  14  ( 56 ). For example, forming deposit  14  may include cold spraying excess first component  18  and second component  20  on to surface  16 , then machining away the excess first component  18  and second component  20 . Machining away the excess first component  18  and second component  20  may enable system  30  to form deposit  14  including more complex geometries, with increased precision (e.g., within predetermined tolerances), or both compared to a technique without machining. 
     Various examples have been described. These and other examples are within the scope of the following claims.