Seed plate for additive manufacturing

Abstract

A method for setting orientation of a single crystal grain or directionally solidified grains within an additively manufactured single crystal or directionally solidified component comprises casting a single crystal structure, slicing the cast single crystal structure into pucks, surface grinding the pucks; and press fitting the pucks into a holding fixture thereby forming a seed plate.

Description

SEED PLATE FOR ADDITIVE MANUFACTURINGCROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This application claims the priority and benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application Serial No. 63 / 615,132 filed December 27, 2023, entitled “SEED PLATE FOR ADDITIVE MANUFACTURING.” U.S. Provisional Patent Application Serial Number 63 / 615,132 is herein incorporated by reference in its entirety.TECHNICAL FIELD

[0002] Embodiments are generally related to manufacturing. Embodiments are related to manufacturing methods and processes. Embodiments are related to additive manufacturing methods and processes. Embodiments are further related to single crystal components. Embodiments are further directed to methods and systems for enabling single crystal, and directionally solidified, components via additive manufacturing.BACKGROUND

[0003] Additive manufacturing using powder bed technologies such as laser powder bed fusion (LPBF) and electron beam melting (EBM) are well known and commonly used. The ability to generate custom metal parts using additive manufacturing has opened the door to a number of new applications for additive manufacturing.

[0004] In general, most additive manufacturing techniques result in a generally undesirable polycrystalline part, or polycrystalline region in the part. For example, in some cases the polycrystalline region may form from un-melted metal powder in the powder bed around the edge of the part, and may act as a nucleation site for growth of the polycrystalline region.

[0005] The much more desirable outcome is the formation of single crystal (SX)(sometimes also referred to as a “mono-crystal”) part. A single crystal part is generally understood to be a part where the crystal lattice of the entire structure is continuous and unbroken throughout, and where there are no defects.

[0006] Single crystal formation is desirable because structures formed with a single crystal structure have a number of advantageous properties. For example, single crystal parts tend to have mechanical stability and are less prone to failure. Single crystal parts can also be anisotropic among myriad other characteristics.

[0007] Engineers and scientists are working to address manufacturing limitations related to polycrystalline growth. For example, some current methods for additive manufacturing use a stainless-steel alloy 304 plate as the platform for LPBF or EBM. However, as these plates are used and resurfaced they are subject to warpage which makes them unsuited for their purpose. Another approach is to use a base material closer to the building material like Nickel Alloy 718. However, use of such plates are expensive and the process for machining such plates is slow. As such, effective methods for additive manufacturing single crystal structures remain elusive.

[0008] Accordingly, there is a need in the art for methods, systems, and processes for enabling single crystal and directionally solidified components via additive manufacturing, as disclosed in the embodiments herein.BRIEF SUMMARY

[0009] The following summary is provided to facilitate an understanding of some of the innovative features unique to the embodiments disclosed and is not intended to be a full description. A full appreciation of the various aspects of the embodiments can be gained by taking the entire specification, claims, drawings, and abstract as a whole.

[0010] It is, therefore, one aspect of the disclosed embodiments to manufacture parts.

[0011] It is another aspect of the disclosed embodiments to manufacture parts via additive manufacturing.

[0012] It is another aspect of the disclosed embodiments to manufacture metal parts with a single crystal structure.

[0013] It is another aspect of the disclosed embodiments to enable single crystal, components via additive manufacturing such as LPBF or EBM.

[0014] It is another aspect of the disclosed embodiments to enable directionally solidified components via additive manufacturing such as LPBF or EBM.

[0015] It is another aspect of the disclosed embodiments to enable single crystal, and directionally solidified components via additive manufacturing such as LPBF or EBM.

[0016] It is another aspect of the disclosed embodiments to provide improved methods and systems for manufacturing single crystal, directionally solidified components using additive manufacturing techniques.

[0017] Another aspect of the disclosed embodiments is a seed plate for use in association with an additive manufacturing methods and systems, to enable the fabrication of single crystal and directionally solidified components.

[0018] For example, in an embodiment, a method comprises casting a single crystalstructure, slicing the cast single crystal structure into at least one puck, and inserting the pucks into a holding fixture thereby forming a seed plate. In an embodiment, the method further comprises surface grinding the at least one puck. In an embodiment, surface grinding the at least one puck denotes grain orientation in the at least one puck. In an embodiment, slicing the cast single crystal structure comprises wire electrical discharge machining (or other known cutting methods in other embodiments) . In an embodiment, the method further comprises forming the holding fixture and forming pattern sockets in the holding fixture configured to accept the at least one puck. In an embodiment, the holding fixture comprises steel. In an embodiment, inserting the pucks into a holding fixture further comprises press fitting the pucks into the holding fixture. In an embodiment, the single crystal structure comprises a cylinder. In an embodiment, the single crystal structure comprises one of: a cuboid, a triangular prism, or an elongated star shape. In an embodiment, the method further comprises installing the seed plate in an additive manufacturing machine. In an embodiment, the additive manufacturing machine comprises a powder bed fusion device.

[0019] In another embodiment, a system comprises a holding fixture and at least one puck installed in the holding fixture thereby forming a seed plate. In an embodiment, the holding fixture further comprises at least one pattern socket. In an embodiment, the system further comprises a pattern of the at least one pattern sockets formed on the holding fixture. In an embodiment, the holding fixture comprises steel (or other such plate materials). In an embodiment, the at least one puck comprises a plurality of pucks. In an embodiment, the plurality of pucks further comprise a cast single crystal structure, sliced into pucks. In an embodiment, the system further comprises a top surface of the at least one puck being surface ground. In an embodiment, the seed plate is configured to be installed in an additive manufacturing machine.

[0020] In another embodiment, a method comprises casting a single crystal structure, slicing the cast single crystal structure into at least one puck, surface grinding the at least one puck, forming a holding fixture, forming a pattern of pattern sockets in the holding fixture configured to accept the at least one puck, and press fitting the puck into a holding fixture thereby forming a seed plate.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying figures, in which like reference numerals refer to identical or functionally similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the embodiments and, together with the detailed description, serve to explain the embodiments disclosed herein.

[0022] FIG. 1 depicts steps associated with a method for creating a seed plate for orientation of a single crystal grain, or directionally solidified grains, within an additively manufactured single crystal or directionally solidified component, in accordance with the disclosed embodiments;

[0023] FIG. 2 depicts exemplary cast single crystal structures, in accordance with the disclosed embodiments;

[0024] FIG. 3 depicts exemplary sliced pucks cut from a cast single crystal structure, in accordance with the disclosed embodiments;

[0025] FIG. 4 depicts an exemplary holding fixture, in accordance with the disclosed embodiments;

[0026] FIG. 5 depicts pucks inserted in the holding fixture thereby forming a seed plate, in accordance with the disclosed embodiments;

[0027] FIG. 6 depicts a seed plate installed in an additive manufacturing device, in accordance with the disclosed embodiments; and

[0028] FIG. 7 depicts steps associated with another exemplary method for orientation of a single crystal grain or directionally solidified grains within an additively manufactured single crystal or directionally solidified component, in accordance with the disclosed embodiments.DETAILED DESCRIPTION

[0029] The particular values and configurations discussed in the following non-limiting examples can be varied and are cited merely to illustrate one or more embodiments and are not intended to limit the scope thereof.

[0030] Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments are shown. The embodiments disclosed herein can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art. Like numbers refer to like elements throughout.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0032] Throughout the specification and claims, terms may have nuanced meanings suggested or implied in context beyond an explicitly stated meaning. Likewise, the phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment and the phrase “in another embodiment” as used herein does not necessarily refer to a different embodiment. It is intended, for example, that claimed subject matter include combinations of example embodiments in whole or in part.

[0033] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. Itwill be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0034] It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method, kit, reagent, or composition of the invention, and vice versa. Furthermore, compositions of the invention can be used to achieve methods of the invention.

[0035] It will be understood that particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.

[0036] The use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and / or the specification may mean “one,” but it is also consistent with the meaning of “one or more,” “at least one,” and “one or more than one.” The use of the term “or” in the claims is used to mean “and / or” unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and “and / or.” Throughout this application, the term “about” is used to indicate that a value includes the inherent variation of error for the device, the method being employed to determine the value, or the variation that exists among the study subjects.

[0037] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive oropen-ended and do not exclude additional, unrecited elements or method steps.

[0038] The term “or combinations thereof” as used herein refers to all permutations and combinations of the listed items preceding the term. For example, “A, B, C, or combinations thereof” is intended to include at least one of: A, B, C, AB, AC, BC, or ABC, and if order is important in a particular context, also BA, CA, CB, CBA, BCA, ACB, BAC, or CAB. Continuing with this example, expressly included are combinations that contain repeats of one or more item or term, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, and so forth. The skilled artisan will understand that typically there is no limit on the number of items or terms in any combination, unless otherwise apparent from the context.

[0039] All of the compositions and / or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions and / or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit, and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.

[0040] The embodiments presented herein are directed to methods and systems for seeding a holding fixture with single crystal plates in order to foster a grain selection process, allowing single crystal (SX) and / or directionally solidified (DS) growth in laser powder bed fusion (L-PBF), electron beam powder bed fusion (EB-PBF), and / or direct energy deposition (DED) fabrication.

[0041] FIG. 1 illustrates a method 100 for creating a seed plate in accordance with the disclosed embodiments. The method starts at 102.

[0042] At step 104 a single crystal structure can be cast. One well-known casting technique is the Bridgman process. In this process, a molten metal alloy is held at vacuum in a mold. The mold is chilled with a cooling chamber, creating a vertical temperature gradient thatcreates directional solidification. It should be appreciated that the Bridgman process is one example of a casting method for producing a single crystal structure with directional solidification, which can be used in accordance with the disclosed embodiments. In other embodiments, other well-known methods of casting a single crystal structure can be used.

[0043] FIG. 2 illustrates a selection of exemplary cast single crystal structures, in accordance with the disclosed embodiments. In certain embodiments, the cast single crystal structure can comprise a cylinder 202. However, in other embodiments, other structures can also be made. For example, the shape of the cast single crystal structure can be a cuboid 204, a triangular prism 206, or an elongated star shape 208. It should be understood that, in other embodiments, any shaped (or cross sectional shape) can be used as the cast single crystal structure. The shape of the cast single crystal structure can be dictated by the shape of the associated mold, used to cast the single crystal structure and the parameters of the ultimate build.

[0044] Once the single crystal structure has been cast, it can be sliced into one or more discs or pucks. In certain embodiments, the single crystal structure can be sliced into pucks using wire electrical discharge machining (wire EDM). Wire EDM uses two electrodes with a dielectric liquid with an electric voltage therebetween. A current between the two electrodes is used to precisely cut hard materials such as the cast single crystal structure. While wire EDM is one option for cutting the single crystal structure into pucks, in other embodiments, other known methods can also be used.

[0045] FIG. 3 illustrates a set of pucks cut from the respective cast single crystal structures. For example, the cylindrical single crystal structure 202, can be cut into a series of discs 302 or pucks. The cuboid 204 can be cut into a series of cuboid discs 304 or pucks. The triangular prism 206 can be cut into a series of smaller cuboid prism discs 306 or pucks. The elongated star shape 208 can be cut into series of smaller elongated star shaped discs 308 or pucks. It should be appreciated that the set of pucks can come from the cast single crystal structure, and can take the shape of the cross-section of the cast single crystal structure. As such, in other embodiments, the series of pucks can have any associated cross-sectional shape, as selected for the specific application. It should also be understood that any number of suchdiscs or pucks can be formed, as dictated by the parameters of the ultimate build design.

[0046] The pucks can be prepared for engagement with a holding fixture by surface grinding the pucks, as illustrated at step 108. Surface grinding smooths the top surface of the puck to a desired level. In addition, the surface grind can be used to denote grain orientation.

[0047] Next at step 110, a holding fixture can be prepared for receiving the pucks. In certain embodiments, the holding fixture can comprise a stainless steel plate, with a series of pattern sockets configured to accept the associated puck or pucks. It should be understood that, in other embodiments, other materials can be used as the holding fixture and / or seed plate.

[0048] FIG. 4 illustrates an exemplary holding fixture 400, in accordance with the disclosed embodiments. The holding fixture 400 can comprise a plate body 402, with a desired thickness 404, a top surface 410, and a bottom surface 411 . The plate body 402, is typically, but not necessarily, made of steel. The holding fixture can be, for example, configured to have a circular shape, or it can be configured in other shapes according to design considerations. The holding fixture 400, can ultimately be used as the base to begin the layer- by-layer fusion process in the powder bed build.

[0049] A series of pattern sockets 406 are formed in the plate body 402. The pattern socket 406 pattern 408 in the plate body 402 can be standardized, or can be selected for a specific application. In certain embodiments, it may be desirable to have a varying number of pattern sockets 406 arranged in a specific location according to the planned additive manufacturing build.

[0050] It should be appreciated that the plate body 402 can have various geometries and the disc geometry illustrated in FIG. 4 is merely exemplary. Likewise, the shape of the pattern sockets 406 can be selected to match the pucks (e.g. pucks 302) created in step 106. Similarly, the depth of the pattern sockets 406 can be selected so that the top surface of the associated pucks (e.g., pucks 302) are flush, or substantially flush, with the top surface 410 of the plate body 402.

[0051] At step 112, the pucks are inserted into the pattern sockets in the plate body. Incertain embodiments, the pucks can be press fit into the build plate holding fixture. In certain exemplary embodiments, no fasteners are used since fasteners could bind due to the very high processing temperatures associated with additive manufacturing methods.

[0052] FIG. 5 illustrates the pucks 302 installed in the pattern sockets 406 of the holding fixture 400. At this point the seeded holding fixture, or seed plate, is ready for installation in an additive manufacturing machine such as an electron beam powder bed fusion machine, a laser powder bed fusion machine, or other such additive manufacturing machine, as illustrated at step 114.

[0053] FIG. 6 illustrates the seeded holding fixture 400 installed as a build plate for an additive manufacturing machine 600, with seed plate pucks (e.g. pucks 302) embedded therein. Again, it should be appreciated that the number and shape of seed plate pucks (pucks 302) is exemplary. In other embodiments any number of pucks in any shape can be used.

[0054] The additive manufacturing machine 600 can comprise a laser powder bed fusion (L-PBF) machine, electron beam powder bed fusion (EB-PBF) machine, and / or direct energy deposition (DED) machine, or other such machine. In FIG. 6, the exemplary additive manufacturing machine illustrated is a laser powder bed fusion machine, but the embodiments can include other such additive manufacturing machines.

[0055] The additive manufacturing machine 600 can comprise an enclosure 602, with an energy source 604. In this embodiment, the energy source 604 comprises a laser source configured for producing a laser beam, but other known energy sources can equivalently be used.

[0056] The additive manufacturing machine 600 can generally include a pedestal 606 used to lower (or raise) a build plate, here embodied as a seeded holding fixture 400, in a build chamber 608. The build chamber 608 can generally comprise the area in which the part 610 is built.

[0057] A separate feed stock chamber 612 is used to hold addition powder feed stock 614A feed stock distributor 616 can be used to provide the powder feed stock 614 from the feed stock chamber 612 to the build chamber 608. In certain embodiments, the powder feed stock can comprise metal powder feed stock 614.

[0058] In operation, the powder feed stock 614 is distributed into the build chamber 608. The energy source 604 can then transfer energy to the layer of powder feed stock 614 causing it to bind. In the embodiments, some or all of the part 610 can be built on the pucks (e.g. 302) embedded in the seeded holding fixture 400. Once a layer is complete, the pedestal 606 can be lowered, and a new layer of powder feed stock 614 is distributed into the build chamber 608 where another layer of the part 610 is completed.

[0059] Aspects of the disclosed embodiments include using the single crystal pucks (e.g. puck 302) embedded in the seeded holding fixture 400, as the base for the part 610 to foster the grain selection process, allowing single crystal (SX) and / or directionally solidified (DS) growth of the part 610. The method ends at step 116.

[0060] FIG. 7 provides a visual representation of a method 700 for creating a seed plate for a powder bed fusion machine, in order to set orientation of a single crystal and / or directionally solidified grains within an additively manufactured single crystal and / or directionally solidified component.

[0061] As illustrated at step 702 a single crystal cast structure 750 can be made. Next at step 704, wire EDM, or other such cutting means can be used to slice the single crystal cast structure into a series of single crystal pucks 752. At step 706, the pucks 752 can be surface ground to a required tolerance as shown at 754. At step 708, the pucks are inserted into a holding fixture 754. The holding fixture 756 is specially configured to accept the pucks 752 so that they are flush, or substantially flush with the surface of the holding fixture 756. Finally, at step 710, the holding fixture 756 is used as a build plate for an additive manufacturing machine 756.

[0062] With the method 700, the seed plate can kickstart the grain selection process, allowing for the growth of SX in L-PBF and EB-PBF quicker and in larger parts than previouslypossible.

[0063] Based on the foregoing, it can be appreciated that a number of embodiments, preferred and alternative, are disclosed herein. In an embodiment, a method comprises casting a single crystal structure, slicing the cast single crystal structure into at least one single crystal puck, and inserting the at least one single crystal puck into a holding fixture thereby forming a seed plate. In an embodiment, the method comprises surface grinding the at least one single crystal puck. In an embodiment, surface grinding the at least one single crystal puck denotes grain orientation in the at least one single crystal puck. In an embodiment, slicing the cast single crystal structure comprises wire electrical discharge machining. In an embodiment, the method comprises forming the holding fixture, and forming pattern sockets in the holding fixture configured to accept the at least one single crystal puck. In an embodiment, the holding fixture comprises steel. In an embodiment, inserting the at least one single crystal puck into a holding fixture further comprises press fitting the at least one single crystal puck into the holding fixture. In an embodiment, the single crystal structure comprises a cylinder. In an embodiment, the single crystal structure comprises one of a cuboid, a triangular prism, or an elongated star shape. In an embodiment, the method comprises installing the seed plate in an additive manufacturing machine. In an embodiment, the additive manufacturing machine comprises a powder bed fusion device.

[0064] In another embodiment a system comprises a holding fixture and at least one single crystal puck installed in the holding fixture thereby forming a seed plate. In an embodiment, the holding fixture further comprises at least one pattern socket. In an embodiment, the system further comprises a pattern of the at least one pattern sockets formed on the holding fixture. In an embodiment, the holding fixture comprises steel. In an embodiment, the at least one single crystal puck comprises a plurality of single crystal pucks. In an embodiment, the plurality of single crystal pucks further comprise a cast single crystal structure, sliced into single crystal pucks. In an embodiment, the system further comprises a top surface of the at least one single crystal puck being surface ground. In an embodiment, the seed plate is configured to be installed in an additive manufacturing machine.

[0065] In an embodiment, a method comprises casting a single crystal structure, slicing the cast single crystal structure into at least one single crystal puck, surface grinding the at least one single crystal puck, forming a holding fixture, forming a pattern of pattern sockets in the holding fixture configured to accept the at least one single crystal puck, and press fitting the at least one single crystal puck into a holding fixture thereby forming a seed plate.

[0066] It should be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. It should be understood that various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Claims

CLAIMSWhat is claimed is:1 . A method comprising: casting a single crystal structure; slicing the cast single crystal structure into at least one single crystal puck; and inserting the at least one single crystal puck into a holding fixture thereby forming a seed plate.

2. The method of claim 1 further comprising: surface grinding the at least one single crystal puck.

3. The method of claim 2 wherein surface grinding the at least one single crystal puck denotes grain orientation in the at least one single crystal puck.

4. The method of claim 1 wherein slicing the cast single crystal structure comprises: wire electrical discharge machining.

5. The method of claim 1 further comprising: forming the holding fixture; and forming pattern sockets in the holding fixture configured to accept the at least one single crystal puck.

6. The method of claim 1 wherein the holding fixture comprises steel.

7. The method of claim 1 wherein inserting the at least one single crystal puck into a holding fixture further comprises: press fitting the at least one single crystal puck into the holding fixture.

8. The method of claim 1 wherein the single crystal structure comprises: a cylinder.

9. The method of claim 1 wherein the single crystal structure comprises one of: a cuboid; a triangular prism; or an elongated star shape.

10. The method of claim 1 further comprising: installing the seed plate in an additive manufacturing machine.1 1 . The method of claim 11 , wherein the additive manufacturing machine comprises a powder bed fusion device.

12. A system comprising: a holding fixture; and at least one single crystal puck installed in the holding fixture thereby forming a seed plate.

13. The system of claim 12 wherein the holding fixture further comprises: at least one pattern socket.

14. The system of claim 13 further comprising: a pattern of the at least one pattern sockets formed on the holding fixture.

15. The system of claim 12 wherein the holding fixture comprises steel.

16. The system of claim 12 wherein the at least one single crystal puck comprises: a plurality of single crystal pucks.

17. The system of claim 15 wherein the plurality of single crystal pucks further comprise: a cast single crystal structure, sliced into single crystal pucks.

18. The system of claim 15 further comprising: a top surface of the at least one single crystal puck being surface ground.

19. The system of claim 12 wherein the seed plate is configured to be installed in an additive manufacturing machine.

20. A method comprising: casting a single crystal structure; slicing the cast single crystal structure into at least one single crystal puck; surface grinding the at least one single crystal puck; forming a holding fixture; forming a pattern of pattern sockets in the holding fixture configured to accept the at least one single crystal puck; and press fitting the at least one single crystal puck into a holding fixture thereby forming a seed plate.

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