Abstract:
A method of manufacturing a component includes additively manufacturing a crucible; directionally solidifying a metal material within the crucible; and removing the crucible to reveal the component. A component for a gas turbine engine includes a directionally solidified metal material component, the directionally solidified metal material component having been additively manufactured of a metal material concurrently with a core, the metal material having been remelted and directionally solidified.

Description:
[0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 14/706,659 filed May 7, 2015, which claims priority to U.S. Patent Appln. No. 61/991,118 filed May 9, 2014. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to components for a gas turbine engine and, more particularly, to the additive manufacture thereof. 
         [0004]    2. Background Information 
         [0005]    Gas turbine engines typically include a compressor section to pressurize airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases. 
         [0006]    In the gas turbine industry, methods for fabricating components with internal passageways, such as blades and vanes within the turbine section, using additive manufacturing invite much attention. Since a component is produced in a continuous process in an additive manufacturing operation, features associated with conventional manufacturing processes such as machining, forging, welding, casting, etc. can be eliminated leading to savings in cost, material, and time. 
         [0007]    An inherent feature of metallic components fabricated by additive manufacturing is that the metallic material forming the component has a polycrystalline microstructure. However, for numerous types of turbine components it is preferable to use a metallic material having a single crystal, or a columnar grain microstructure, which microstructure is able to withstand the higher temperatures and stresses typically experienced in the operating environment in a hot gas stream. 
       SUMMARY 
       [0008]    A method of manufacturing a component according to one disclosed non-limiting embodiment of the present disclosure includes additively manufacturing a crucible for forming the component; solidifying a metal material within the crucible to form a metal directionally solidified microstructure within the component; and removing a sacrificial core to reveal the component. 
         [0009]    In a further embodiment of the present disclosure, the step of solidifying the metal material includes directionally solidifying the material to have a single crystal microstructure. 
         [0010]    In a further embodiment of the present disclosure, the step of solidifying the metal material includes directionally solidifying the material to have a columnar grain microstructure. 
         [0011]    In a further embodiment of the present disclosure, the metal material is selected from the group consisting of a nickel based superalloy, cobalt based superalloy, iron based superalloy, and mixtures thereof. 
         [0012]    In a further embodiment of the present disclosure, the crucible is additively manufactured of at least one of a ceramic material, a refractory metal alloy, or combinations thereof. 
         [0013]    In a further embodiment of the present disclosure, the metal material is a powder. 
         [0014]    In a further embodiment of the present disclosure, the crucible includes a core at least partially within a shell, the core at least partially defines at least one internal passageway within the component. 
         [0015]    A further embodiment of the present disclosure includes forming the core via additive manufacturing. 
         [0016]    A further embodiment of the present disclosure includes forming the shell via additive manufacturing. 
         [0017]    In a further embodiment of the present disclosure, the core at least partially defines the internal passageways within the component. 
         [0018]    A method of manufacturing a component according to another disclosed non-limiting embodiment of the present disclosure includes additively manufacturing the component of a metal material; additively manufacturing a core at least partially within the component; at least partially encasing the additively manufactured component and additively manufactured core within a shell; melting the additively manufactured component; solidifying the metal material of the additively manufactured component to form a metal directionally solidified microstructure; and removing the shell and the additively manufactured core from the directionally solidified component. 
         [0019]    In a further embodiment of the present disclosure, the step of solidifying the metal material includes directionally solidifying the material to have a single crystal microstructure. 
         [0020]    In a further embodiment of the present disclosure, the step of solidifying the metal material includes directionally solidifying the material to have a columnar grain microstructure. 
         [0021]    In a further embodiment of the present disclosure, the metal material is a powder. 
         [0022]    In a further embodiment of the present disclosure, the core at least partially defines at least one internal passageway within the component. 
         [0023]    A further embodiment of the present disclosure includes concurrently additively manufacturing the component of a metal material and the core within the component. 
         [0024]    In a further embodiment of the present disclosure, the core at least partially defines microchannels within the component. 
         [0025]    In a further embodiment of the present disclosure, the microchannels are additively manufactured of a refractory material and the internal passageways are manufactured of a ceramic material. 
         [0026]    In a further embodiment of the present disclosure, the additive manufacturing is performed by a multi-powder bed system. 
         [0027]    A further embodiment of the present disclosure includes applying a wax material at least partially onto the component. 
         [0028]    A further embodiment of the present disclosure includes melting the wax material prior to melting the additively manufactured component. 
         [0029]    A further embodiment of the present disclosure includes applying the wax material to an airfoil portion of the component. 
         [0030]    A component for a gas turbine engine, according to another disclosed non-limiting embodiment of the present disclosure includes a metal directionally solidified material component, the metal directionally solidified material component having been additively manufactured of a metal material concurrently with a core, the metal material having been remelted and directionally solidified. 
         [0031]    In a further embodiment of the present disclosure, the component has a directionally solidified single crystal microstructure. 
         [0032]    In a further embodiment of the present disclosure, the component has a directionally solidified columnar grain microstructure. 
         [0033]    In a further embodiment of the present disclosure, the metal single crystal material component includes an airfoil. 
         [0034]    In a further embodiment of the present disclosure, the metal single crystal material component is a rotor blade. 
         [0035]    The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, the following description and drawings are intended to be exemplary in nature and non-limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows. 
           [0037]      FIG. 1  is a schematic cross-section of an example of gas turbine engine architecture. 
           [0038]      FIG. 2  is a schematic cross-section of another example of gas turbine engine architecture. 
           [0039]      FIG. 3  is an enlarged schematic cross-section of an engine turbine section. 
           [0040]      FIG. 4  is a perspective view of a turbine blade as an example component with internal passages. 
           [0041]      FIG. 5  is a schematic cross-section view of the showing the internal passages. 
           [0042]      FIG. 6  illustrates a crucible in accordance with aspects of this disclosure. 
           [0043]      FIG. 7  is a schematic lateral cross-section view of the example component with internal passages within the crucible. 
           [0044]      FIG. 8  is a flow chart of one disclosed non-limiting embodiment of a method for fabricating an example component with internal passages. 
           [0045]      FIG. 9  is a flow chart of another disclosed non-limiting embodiment of a method for fabricating an example component with internal passages. 
           [0046]      FIG. 10  is a lateral cross-section view of an example component with internal passages within a crucible as manufactured by the method of  FIG. 9 . 
           [0047]      FIG. 11  is a flow chart of another disclosed non-limiting embodiment of a method for fabricating an example component with internal passages. 
           [0048]      FIG. 12  is a lateral cross-section view of an example component with internal passages within a crucible as manufactured by the method of  FIG. 11 . 
           [0049]      FIG. 13  is a flow chart of another disclosed non-limiting embodiment of a method for fabricating an example component with internal passages. 
           [0050]      FIG. 14  is a lateral cross-section view of an example component with internal passages within a crucible as manufactured by the method of  FIG. 13 . 
           [0051]      FIG. 15  is a flow chart of another disclosed non-limiting embodiment of a method for fabricating an example component with internal passages. 
           [0052]      FIG. 16  is a lateral cross-section view of an example component with internal passages within a crucible and coated with a wax layer as manufactured by the method of  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION 
       [0053]      FIG. 1  schematically illustrates a gas turbine engine  20 . The gas turbine engine  20  is disclosed herein as a two-spool turbo fan that generally incorporates a fan section  22 , a compressor section  24 , a combustor section  26  and a turbine section  28 . Alternative engine architectures  200  might include an augmentor section  12 , an exhaust duct section  14  and a nozzle section  16  ( FIG. 2 ) among other systems or features. The fan section  22  drives air along both a bypass flowpath and into the compressor section  24 . The compressor section  24  drives air along a core flowpath for compression and communication into the combustor section  26  then expansion through the turbine section  28 . Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engine architectures such as turbojets, turboshafts, and three-spool (plus fan) turbofans. 
         [0054]    The engine  20  generally includes a low spool  30  and a high spool  32  mounted for rotation about an engine central longitudinal axis X relative to an engine static structure  36  via several bearing structures  38 . The low spool  30  generally includes an inner shaft  40  that interconnects a fan  42 , a low pressure compressor (“LPC”)  44  and a low pressure turbine (“LPT”)  46 . The inner shaft  40  drives the fan  42  directly or through a geared architecture  48  to drive the fan  42  at a lower speed than the low spool  30 . An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system. 
         [0055]    The high spool  32  includes an outer shaft  50  that interconnects a high pressure compressor (“HPC”)  52  and high pressure turbine (“HPT”)  54 . A combustor  56  is arranged between the high pressure compressor  52  and the high pressure turbine  54 . The inner shaft  40  and the outer shaft  50  are concentric and rotate about the engine central longitudinal axis “A” which is collinear with their longitudinal axes. 
         [0056]    Core airflow is compressed by the LPC  44  then the HPC  52 , mixed with the fuel and burned in the combustor  56 , then expanded over the HPT  54  and the LPT  46 . The turbines  54 ,  46  rotationally drive the respective low spool  30  and high spool  32  in response to the expansion. The main engine shafts  40 ,  50  are supported at a plurality of points by bearing structures  38  within the static structure  36 . Bearing structures  38  at various locations may alternatively or additionally be provided. 
         [0057]    With reference to  FIG. 3 , an enlarged schematic view of a portion of the turbine section  28  is shown by way of example; however, other engine sections will also benefit here from. A full ring shroud assembly  60  within the engine case structure  36  supports a blade outer air seal (BOAS) assembly  62  with a multiple of BOAS segments  64  proximate to a rotor assembly  66  (one schematically shown). 
         [0058]    The full ring shroud assembly  60  and the blade outer air seal (BOAS) assembly  62  are axially disposed between a forward stationary vane ring  68  and an aft stationary vane ring  70 . Each vane ring  68 ,  70  includes an array of vanes  72 ,  74  that extend between a respective inner vane support  76 ,  78  and an outer vane support  80 ,  82 . The outer vane supports  80 ,  82  are attached to the engine case structure  36 . 
         [0059]    The rotor assembly  66  includes an array of blades  84  circumferentially disposed around a disk  86 . Each blade  84  includes a root  88 , a platform  90  and an airfoil  92  (also shown in  FIG. 4 ). A portion of each blade root  88  is received within a rim  94  of the disk  86 . Each airfoil  92  extends radially outward, and has a tip  96  disposed in close proximity to a blade outer air seal (BOAS) assembly  62 . Each BOAS segment  64  may include an abradable material to accommodate potential interaction with the rotating blade tips  96 . 
         [0060]    To resist the high temperature stress environment in the hot gas path of a turbine engine, each blade  84  may be formed to have a single crystal or columnar grain microstructure. It should be appreciated that although a blade  84  with internal passageways  98  ( FIG. 5 ) will be described and illustrated in detail, other components including, but not limited to, vanes, fuel nozzles, airflow swirlers, combustor liners, turbine shrouds, vane endwalls, airfoil edges and other gas turbine engine components “W” may also be manufactured in accordance with the teachings herein. 
         [0061]    The present disclosure involves the use of additive manufacturing techniques to form a component “W”, as will be disclosed in the embodiments described below. In general terms, additive manufacturing techniques allow for the creation of a component “W” by building the component with successively added layers; e.g., layers of powdered material. The additive manufacturing process facilitates manufacture of relatively complex components, minimize assembly details and minimize multi-component construction. In the additive manufacturing process, one or more materials are deposited on a surface in a layer. In some instances, the layers are subsequently compacted. The material(s) of the layer may be subsequently unified using any one of a number of known processes (e.g., laser, electron beam, etc.). Typically, the deposition of the material (i.e. the geometry of the deposition later for each of the materials) is computer controlled using a three-dimensional computer aided design (CAD) model. The three-dimensional (3D) model is converted into a plurality of slices, with each slice defining a cross section of the component for a predetermined height (i.e. layer) of the 3D model. The additively manufactured component is then “grown” layer by layer; e.g., a layer of powdered material(s) is deposited and then unified, and then the process is repeated for the next layer. Examples of additive manufacturing processes that can be used with the present disclosure include, but are not limited to, Stereolithography (SLS), Direct Selective Laser Sintering (DSLS), Electron Beam Sintering (EBS), Electron Beam Melting (EBM), Laser Engineered Net Shaping (LENS), Laser Net Shape Manufacturing (LNSM), Direct Metal Deposition (DMD), Direct Metal Laser Sintering (DMLS) and others. The present disclosure is not limited to using any particular type of additive manufacturing process. 
         [0062]    In the embodiments described below, an additive manufacturing process is utilized to form a crucible  100  ( FIG. 6 ) and a component “W”  84  (e.g., a blade, a vane, etc.). With reference to  FIG. 6 , the additive manufactured crucible  100  generally includes a core  102  and a shell  104 . The shell  104  and the core  102  define the geometry of the component “W” (e.g., including complex exterior and interior geometries of the component “W”), and provide a support structure for the component “W”. The shell  104  forms a structure having surfaces that will define the outer surfaces of the component “W”. The core  102  forms bodies that occupy volumes that will be voids (e.g., internal passages) within the final component “W”. The crucible  100  may comprise a variety of different material types; e.g., refractory metals, ceramics, combinations thereof, etc. As will be explained below, the crucible  100  may be utilized as a melting unit and/or a die during processing of the component “W”. 
         [0063]    With reference to  FIG. 8 , according to one disclosed non-limiting embodiment for forming single crystal or columnar grain superalloy component with internal passageways, a method includes forming a crucible  100 . The crucible  100  is additively manufactured (Step  202 ). It should be appreciated that the core  102  and/or shell  104  of the crucible  100  may be additively manufactured from materials that include, but are not limited to, ceramic material such as silica, alumina, zircon, cobalt, mullite, kaolin, refractory metals, combinations thereof, etc. 
         [0064]    Following additive manufacture, the crucible  100  may be dried and fired (i.e. bisqued) at an intermediate temperature before high firing to fully sinter and densification. The additively manufactured crucible  100  thereby forms a cavity for forming the component W. That is, the crucible  100  is integrally formed by the additive manufacturing process such that the conventional separate manufacture of the core and shell are essentially combined into a single step. It should be appreciated that single or multiple molds and cavities may be additively manufactured and assembled. 
         [0065]    The crucible  100  may then be filled with a component material such as a desired metal (Step  204 ). Non-limiting examples of metal component materials include superalloys; e.g., nickel based superalloys, cobalt based superalloys, iron based superalloys, combinations thereof, etc. In some instances, the component material added to the crucible  100  may be in powder form that can be subsequently melted. In other instances, the component material added to the crucible  100  may be in molten form that is subsequently solidified. The present disclosure is not limited, however, to adding component material in any particular form. 
         [0066]    In some instances, the crucible is combined or utilized with structure (e.g., a starter seed and a chill plate) operable to cause the component W to be formed having a directionally solidified microstructure (i.e., a “DS” microstructure), such as a single crystal microstructure or a columnar grain microstructure. A single crystal solid (sometimes referred to as a “monocrystalline solid”) component is one in which the crystal lattice of the substantially all of the component material is continuous and unbroken to the edges of the component, with virtually no grain boundaries. Processes for growing a single crystal alloy structure are believed to be known to those of ordinary skill in the art, and therefore descriptions of such processes are not necessary here for enablement purposes. However, an example is provided hereinafter to facilitate understanding of the present disclosure. A portion of a metallic starter seed may extend into a vertically lower portion of the component material receiving portion of the crucible  100 . During subsequent processing of the component “W”, molten component material contacts the starter seed and causes the partial melt back thereof. The component material is subsequently solidified by a thermal gradient moving vertically through the crucible  100 ; e.g., the component is solidified epitaxially from the unmelted portion of the starter seed to form the single crystal component. The thermal gradient used to solidify the component may be produced by a combination of mold heating and mold cooling; e.g., using a mold heater, a mold cooling cone, a chill plate and withdrawal of the component being formed. As indicated above, the aforesaid description is an example of how a single crystal microstructure component may be formed, and the present disclosure is not limited thereto. 
         [0067]    Now referring again to the embodiment described in  FIG. 8 , a single crystal starter seed or grain selector may be utilized to enable the component “W” to possess a single crystal microstructure (or other DS microstructure) during solidification (Step  206 ). The solidification may utilize a chill block in a directional solidification furnace. The directional solidification furnace has a hot zone that may be induction heated and a cold zone separated by an isolation valve. The chill block and additively manufactured crucible  100  may be elevated into the hot zone and filled with molten super alloy. After the pour, or being molten, the chill plate may descend into the cold zone causing a solid/liquid interface to advance from the partially molten starter seed, creating the desired single crystal microstructure (or other DS microstructure type) as the solid/liquid interface advances away from the starter seed. The formation process may be performed within an inert atmosphere or vacuum to preserve the purity of the component material being formed. 
         [0068]    Following solidification, the additively manufactured crucible  100  may be removed from the solidified component “W” by various techniques (e.g., caustic leaching), thereby leaving behind the finished single crystal component (Step  208 ). After removal, the component W may be further finished such as by machining, threading, surface treating, coating or any other desirable finishing operation (Step  210 ). 
         [0069]    Now referring to  FIGS. 9 and 10 , in another non-limiting embodiment a method  300  includes additively manufacturing a component “W” (e.g. a turbine blade, vane, etc.) having internal cooling passages (Step  302 ) and a crucible  100 . In this embodiment, the component “W” and the crucible  100  are additively manufactured using a multi-feedstock process such as a two-powder bed system. A structure  130  of the component W is manufactured of the desired superalloy, while the core  102  and shell  104  of the crucible  100  are manufactured of a different material such as a ceramic, a refractory metal, or other material which is later removed ( FIG. 10 ). With respect to the internal cooling passages of the component “W”, during the additive manufacturing process, a ceramic material, a refractory metal material, or other core  102  material is formed at the locations within the layers of the additively formed structure to coincide with the locations of the voids that will form the passages within the component. The core  102  within the component structure  130  and the shell  104  that surrounds the component structure  130  are later removed; e.g., in a manner as described above. 
         [0070]    The structure  130  of the component W, being additively manufactured, may be a polycrystalline superalloy. As indicated above, it may be desirable for the component structure  130  to have a single crystal microstructure (or other DS microstructure) that is better suited to withstand the high temperature, high stress operating environment of the gas turbine engine. 
         [0071]    To thereby facilitate formation of a component having a single crystal microstructure (or other DS microstructure), the additively manufactured superalloy structure  130  is re-melted within the crucible  100  (Step  304 ). For example, the additively manufactured superalloy structure  130  may be re-melted and directionally solidified (e.g., as described above) to form a metal single crystal structure (or other DS microstructure) within the crucible  100 . As indicated above, the present disclosure is not limited to any particular technique for creating the single crystal microstructure. 
         [0072]    Following solidification, the additively manufactured crucible  100  may be removed from the solidified component W such as by caustic leaching, to leave the finished single crystal component (Step  306 ). After removal, the component W may be further finished such as by machining, threading, surface treating, coating or any other desirable finishing operation (Step  308 ). 
         [0073]    Now referring to  FIGS. 11 and 12 , a method  400  according to another non-limiting embodiment includes additively manufacturing component “W” with a multi-feedstock additive manufacturing process such as three-powder bed system (Step  402 ). The component “W”  140  is manufactured of the desired superalloy while the core  102  and shell  104  of the crucible  100  are manufactured of a different material ( FIG. 12 ). Locations for the internal cooling passages  142  of the component “W” are additively manufactured of ceramic material and locations for microcircuits  144  of the component “W” are additively manufactured of a refractory metal material. The microcircuit  144  is relatively smaller than, and may be located outboard of, the internal cooling passages  142  to facilitate tailorable, high efficiency convective cooling. The bodies formed to create the microcircuits may be formed of refractory metals (e.g., molybdenum (Mo), Tungsten (W), etc.) that possess relatively high ductility for formation into complex shapes and have melting points that are in excess of typical casting temperatures of nickel based superalloys. Refractory metals of this type can be removed by various know techniques (e.g., chemical removal, thermal leeching, oxidation methods, etc.) to leave behind a cavity forming the microcircuit  144 . 
         [0074]    As described above, to facilitate formation of a component having a single crystal microstructure (or other DS microstructure), the additively manufactured component  140  is re-melted within the crucible  100  (Step  404 ) formed in step  402 , and subjected to processes for creating the single crystal microstructure (or other DS microstructure type) within the component  140 . As indicated above, the present disclosure is not limited to any particular technique for creating the single crystal microstructure. 
         [0075]    Following solidification, the additively manufactured crucible  100  may be removed from the solidified component W such as by caustic leaching, to leave the finished single crystal component “W”  140  (Step  406 ). After removal, the component “W” may be further finished such as by machining, threading, surface treating, coating or any other desirable finishing operation (Step  408 ). 
         [0076]    Now referring to  FIGS. 13 and 14 , a method  500  according to another disclosed non-limiting embodiment includes additively manufacturing component “W” with a multi-feedstock additive manufacturing process such as two-powder bed system (Step  502 ). The component “W”  150  is manufactured of the desired superalloy while microcircuits  152  of the component “W” are additively manufactured of a refractory metal material. That is, the refractory metal material is additively manufactured within the structure  150  where the microcircuits  152  will be located. 
         [0077]    In this embodiment, the internal cooling passages  154  of the component W may be filled with a ceramic slurry to form the core  102  (Step  504 ). The slurry may include, but is not limited to, ceramic materials commonly used as core materials including, but not limited to, silica, alumina, zircon, cobalt, mullite, and kaolin. In the next step, the ceramic core may be cured in situ by a suitable thermal process if necessary (Step  506 ). 
         [0078]    Next, a ceramic shell may then be formed over the component  150  and internal ceramic core (Step  508 ). The ceramic shell may be formed over the component  150  and ceramic core by dipping it into ceramic powder and binder slurry to form a layer of ceramic material covering the component  150 . The slurry layer is dried and the process repeated for as many times as necessary to form a green (i.e. unfired) ceramic shell mold. The thickness of the green ceramic shell mold at this step may be from about 0.2-1.3 inches (5-32 mm) The green shell mold may then be bisque fired at an intermediate temperature to partially sinter the ceramic and burn off the binder material. The mold may then be high fired at a temperature between about 1200° F. (649° C.) to about 1800° F. (982° C.) from about 10 to about 120 minutes to sinter the ceramic to full density to form the shell mold. 
         [0079]    As described above, to facilitate formation of a component having a single crystal microstructure (or other DS microstructure), the additively manufactured component is re-melted within the crucible  100  (Step  510 ), and subjected to processes for creating the single crystal microstructure (or other DS microstructure type) within the component  150 . As indicated above, the present disclosure is not limited to any particular technique for creating the single crystal microstructure. 
         [0080]    Following solidification, the additively manufactured crucible  100  may be removed from the solidified component W such as by caustic leaching, to leave the finished single crystal component “W”  150  (Step  512 ). After removal, the component “W” may be further finished such as by machining, threading, surface treating, coating or any other desirable finishing operation (Step  514 ). 
         [0081]    Now referring to  FIGS. 15 and 16 , a method  600  according to another disclosed non-limiting embodiment facilitates a high quality surface finish. As described above, the component “W” is additively manufactured of a desired superalloy that itself forms the cavity pattern for the crucible. The additively manufactured component “W” is then re-melted within the crucible to facilitate formation of the single crystal microstructure. However, the crucible, being formed by the additive manufactured structure, may have a relatively poor surface finish typically not acceptable for use as a blade or vane in the gas turbine engine. That is, the airfoil surfaces of the blade and vanes in the gas turbine engine necessarily require particular contour tolerances and surface finishes that are typically not achieved by direct additive manufacture or may not be achieved in an additive manufacturing process within a reasonable cycle time. 
         [0082]    To further improve the finish of an exterior surface of a component “W”  160  (additively manufactured according to any of the above-described embodiments), a relatively thin layer of a wax material  166  may be applied to an external, aerodynamic surface  168  (e.g. an airfoil surface) of the component  160  (Step  604 ;  FIG. 16 ). The wax material provides a smoother surface finish than the relatively rough surface of an additively manufactured component  160 . 
         [0083]    Next, a ceramic shell  104  is formed over the structure  160  (Step  606 ). The ceramic shell may be formed over the additively manufactured structure  160  by dipping or other process. 
         [0084]    The relatively thin layer of a wax material  166  is subsequently removed (Step  608 ). The relatively thin layer of a wax material  166  may be removed by heating or other operation that but does not otherwise effect the additively manufactured structure  160 . 
         [0085]    Then, as described above, to facilitate formation of the single crystal microstructure (or other DS microstructure), the additively manufactured superalloy structure  160  is re-melted within the shell of the crucible (Step  610 ), and subjected to processes for creating the single crystal microstructure (or other DS microstructure type) within the component  150 . As indicated above, the present disclosure is not limited to any particular technique for creating the single crystal microstructure. It should be further appreciated that the re-melting (Step  610 ) may alternatively be combined with the removal of the relatively thin layer of a wax material  166  (Step  608 ). 
         [0086]    Following solidification, the solidified component W may be removed from the crucible by caustic leaching, to leave the finished single crystal structure  160  of the component W (Step  612 ). After removal, the component W may be further finished such as by machining, threading, surface treating, coating or any other desirable finishing operation (Step  614 ). 
         [0087]    The method disclosed herein facilitates the relatively rapid additive manufacture of single crystal microstructure (or other DS microstructure type; e.g., columnar grain) components with complex internal passages and heretofore unavailable surface finishes to withstand the high temperature, high stress operating environment of a gas turbine engine environment. While some of the illustrative embodiments described herein related to the use of metal materials, other materials may be used. For example, in some embodiments a material that may be used may include silicon. 
         [0088]    It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting. 
         [0089]    It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit here from. 
         [0090]    Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure. 
         [0091]    The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content.