EP4351821A1

EP4351821A1 - Method for manufacturing a component by means of layered construction

Info

Publication number: EP4351821A1
Application number: EP22732482.9A
Authority: EP
Inventors: Carolin KÖRNER; Julian Pistor
Original assignee: Friedrich Alexander Univeritaet Erlangen Nuernberg FAU
Current assignee: Friedrich Alexander Univeritaet Erlangen Nuernberg FAU
Priority date: 2021-06-07
Filing date: 2022-06-02
Publication date: 2024-04-17
Also published as: WO2022258475A1; DE102021114560A1

Abstract

The invention relates to a method for manufacturing a component (1) by means of layered construction, by combining a plurality of crystallites of a metal material to form a single crystal. The single crystal is produced by means of thermomechanically activated successive anisotropic plastic deformation. The metal material is heated during the construction of a new layer so that the metal material is melted in a line-shaped region (2). The line-shaped region (2) is moved in order to construct the new layer.

Description

Process for the production of a component by building up layers

The invention relates to a method for producing a component by building up layers. The component includes at least one single crystal. The conventional production of single crystals is usually based on epitaxial crystal growth starting from a seed crystal. The controlled single-crystal growth can then take place either according to the Czochralski method by drawing crucibles, by zone melting or by directional solidification according to the Bridgman method. The crystal orientation of the seed crystal determines the crystal orientation of the resulting single crystal.

European patent specification EP 1 495 166 B1 relates to a method for producing monocrystalline metallic layers on a monocrystalline substrate by means of layer construction by epitaxial growth starting from a material, for example in powder form. The substrate is in particular a workpiece to be repaired or reconditioned. The European patent application EP 3459654 A1 also relates to a method for producing monocrystalline metallic layers on a monocrystalline substrate while retaining the monocrystalline microstructure.

The Bridgman process known, for example, from the German patent application DE 102014 113806 A1 is used to produce monocrystalline turbine blades from a nickel-based alloy. A single crystal is realized by selecting exactly one grain. For this purpose, crystals whose crystal orientation almost coincides with the direction of solidification are selected from a very large number of seed crystals by directional solidification by grain selection. In cubic crystal systems, the direction of solidification corresponds to the <001> direction of the crystals. After this first selection over a length of a few centimetres, a further, geometric selection is made with the help of a spiral selector. The secondary crystal orientation of the single crystals is determined randomly by the spiral selector.

A disadvantage of this method is that it cannot be used to set a more precise crystal orientation. The crystal orientation in the solidification direction can deviate a few degrees from the desired crystal orientation. The secondary crystal orientation cannot be influenced at all.

The object of the present invention is to eliminate the disadvantages of the prior art. In particular, a method is to be specified with which the crystal orientation of single crystals can be optimized. This should in particular improve the quality of the production of monocrystals. Furthermore, a component with a single crystal should also be controlled produced crystal orientation provided and a method for its production are given.

According to the invention, this object is achieved by a method according to the subject matter of claim 1 and by a component according to the subject matter of claim 20. Advantageous refinements of the invention are specified in each case in the dependent claims.

According to the invention, a component is produced by building up layers by combining a multiplicity of crystallites of a metallic material to form a single crystal. The single crystal is created by thermo-mechanically activated successive anisotropic plastic deformation. The metallic material is heated while a new layer is being built up, so that the metallic material is melted in a linear area. The line-shaped area is moved to build the new layer.

The term “thermo-mechanically activated successive anisotropic plastic deformation” is understood to mean plastic deformation of the metallic material, which is caused by mechanical stresses occurring during heating, in particular melting, and subsequent cooling, in particular solidification, of the metallic material. During heating, in particular melting, and subsequent cooling, in particular solidification, thermal expansion can occur, which causes the mechanical stresses. The mechanical stresses are preferably generated in a targeted manner by adjusting the direction of expansion, speed and/or temperature of the melted linear area and/or its surroundings. The mechanical stresses preferably exceed the yield point of the metal materials. The mechanical stresses preferably have a preferred direction due to the linear configuration of the melted linear area. An anisotropic mechanical stress field is thus generated. This results in an anisotropic plastic deformation. This anisotropy preferably leads to the production of a single crystal. The metallic material is gradually subjected to plastic deformation in sections, that is to say successively. The component is built up in layers in one direction. The individual layers are also preferably built up gradually, in that the melted linear area runs through them. The crystal orientation, in particular the primary (in the structure direction) and secondary (in the plane of the layer) crystal orientation, can be set precisely by the thermo-mechanical stress field generated in a targeted manner by adjusting the direction of expansion, speed and/or temperature of the melted linear area.

The mechanical stresses can be compressive stresses or tensile stresses.

The mechanical stresses occur primarily in the metallic material of a new layer and the metallic material that has already solidified in the course of the layered structure, in particular in the region of up to 5 mm below the new layer. Preferably, the already solidified material located immediately below the new layer, in particular up to 5 mm below it, also exhibits mechanical stresses.

The component is preferably subjected to mechanical clamping in the course of a materially bonded connection created by melting metallurgy. As a result, mechanical stresses are not relieved by the single crystal that has already grown evading, and in this context one speaks of self-clamping. The mechanical stresses arise in particular from the interaction of thermal expansion and self-restraint.

The component is preferably built up gradually on a base plate. The base plate can be made of the same metallic material as the component. Alternatively, the bottom plate can be formed from a different metallic material.

The component is preferably constructed with a crystal structure that differs from that of the base plate. The component therefore preferably differs from the base plate in its crystal structure.

The component can be separated from the base plate after its completion. In this case, an initial region of the component is preferably additionally separated off, in which a monocrystalline state has not yet been established.

Alternatively, the component can be built up gradually starting from a powder bed. In this embodiment, too, after the component has been completed, an initial region of the component in which a monocrystalline state has not yet set is preferably separated off.

In a departure from the prior art, the component is therefore preferably not produced starting from a monocrystalline substrate. The component is preferably built up on a polycrystalline base plate or on a powder bed. After its completion, the component is preferably separated from the base plate and/or from an initial region of the component in which a single-crystal state has not yet been established. Furthermore, the component can be constructed so weakly connected to the base plate that the component can be easily removed from the base plate. For this purpose, the component can be sintered onto the base plate, for example.

In the context of the present application, the term “linear area” refers to the linear area melted according to the claims. A repetition of the term "melted" is usually avoided. The line-shaped area has an extension direction. Preferably, significantly greater mechanical stresses arise due to the self-restraint in this direction of expansion than perpendicular to it in the plane of the new layer. The line-shaped area is preferably moved perpendicularly to its direction of extension. Accordingly, much stronger mechanical stresses arise due to the self-constraint in the direction of extension of the line-shaped area than in the direction of movement of the line-shaped area.

The mechanical stress field is therefore anisotropic. This anisotropy leads to anisotropic plastic deformation and generation of a single crystal. By adjusting the direction of extension of the line-shaped area and the mechanical stress field generated thereby, the crystal orientation, in particular the primary and secondary crystal orientation, can preferably be precisely adjusted. In the context of this patent application, a distinction is made between the primary and the secondary crystal orientation as regards the crystal orientation. To explain the primary and secondary crystal orientation, a construction space with an xy-plane as the construction plane and a z-direction as the construction direction is assumed. The primary crystal orientation indicates the alignment of the single crystal or an axis of the single crystal with respect to the z-direction. The single crystal is preferably aligned in the z-direction, but can also be tilted with respect to the z-direction. The secondary crystal orientation stands for a specific rotational position of the crystal lattice around the axis of the single crystal. When the monocrystal is oriented in the z-direction, the secondary crystal orientation refers to the specific rotational position of the crystal lattice about the z-axis, or to put it another way, the position of the crystal lattice in the xy plane.

The linear area is preferably surrounded by a heat-affected zone. The metallic material is preferably not melted in the heat-affected zone. To put it more precisely, the metallic material is preferably not yet melted in part in the heat-affected zone, and in part no longer melted. The heat-affected zone is preferably moved together with the line-shaped area to build up the new layer. In the heat-affected zone, there are preferably high temperature gradients. This leads to particularly strong thermally induced mechanical stresses in the heat-affected zone. The mechanical stresses in the heat-affected zone preferably exceed the yield point. Therefore, plastic deformation of the metallic material preferably occurs in the heat-affected zone. The shape of the heat-affected zone preferably essentially corresponds to the shape of the linear area. The mechanical stresses in the Heat-affected zones therefore also have a preferred direction. The plastic deformation in the heat-affected zone is therefore also anisotropic. The heat-affected zone thus preferably contributes to the production of a single crystal whose crystal orientation, preferably in its primary and secondary crystal orientation, is set precisely.

A temperature field is preferably generated in the installation space. A heat input can take place directly in the linear area, in the heat-affected zone, in the new layer, in the layer produced immediately before the new layer and/or in the layers produced immediately before the new layer. Alternatively or additionally, heat can be applied to the entire installation space, in particular from the outside.

The metallic material can be heated to a first temperature and/or a first temperature range directly in the line-shaped area while the new layer is being built up. This means that a heat input takes place directly in the linear area.

The metallic material in the heat-affected zone is preferably heated to a second temperature and/or a second temperature range. The first temperature or the first temperature range is preferably higher than the second temperature or the second temperature range.

The metallic material is preferably heated to at least a third temperature and/or a third temperature range throughout the new layer during the build-up of the new layer. The third temperature is also referred to as the construction temperature. The second temperature or the second The temperature range is preferably higher than the third temperature or the third temperature range.

In order to heat the metallic material in the entire new layer, heat can also be applied directly to the new layer outside of the line-shaped area. Preferably, the heat input per unit area directly in the line-shaped region is greater than the heat input per unit area directly on the new layer outside the line-shaped region.

A depth of the line-shaped area may be limited to the new layer. The line-shaped area preferably extends through the new layer and penetrates into the layer produced immediately before the new layer and/or into the layers produced immediately before the new layer. The depth of the line-shaped region preferably extends across the new layer and to one to ten, more preferably five to ten layers produced immediately before the new layer. As a result, the metallic material is preferably repeatedly subjected to melting and solidification.

In the heat-affected zone, the temperature field also acts on metallic material that has already solidified in the layer produced immediately before the new layer and/or in the layers produced immediately before the new layer. These layers are also mechanically braced. This means that the mechanical stress field also extends to the layer produced directly in front of the new layer or to the layers produced directly in front of the new layer. The production of the monocrystal can be favored by this already existing anisotropic stress field. The mechanical stresses can exceed the yield point, particularly in the linear area, in the heat-affected zone, in the new layer, in the layer produced immediately before the new layer and/or in the layers produced immediately before the new layer. Therefore, in the linear area, in the heat-affected zone, in the new layer, in the layer produced immediately before the new layer and/or in the layers produced immediately before the new layer, plastic deformations can occur which, due to the anisotropy of the mechanical stresses, are preferred contribute to the production of a single crystal whose crystal orientation, preferably in its primary and secondary crystal orientation, is set precisely.

The metallic material in the line-shaped area can be melted during the build-up of the new layer with one or more temporal interruptions. The metallic material in the line-shaped area is preferably continuously melted during the build-up of the new layer.

The crystallites preferably have a size in a range from 5 μm to 500 μm, preferably in a range from 20 μm to 200 μm, particularly preferably in a range from 40 μm to 150 μm. Preferably at least 100, more preferably at least 100,000, particularly preferably at least 100,000,000 are combined to form one layer of the single crystal. Preferably at least 1,000, more preferably at least 1,000,000, particularly preferably at least 1,000,000,000 crystallites are combined to form the single crystal. The method is preferably carried out in a hermetically sealed chamber. The chamber can be evacuated and/or filled with inert gas. This allows the material properties to be controlled particularly well. In addition, the component is protected from unwanted oxidation.

The component can also be produced with several single crystals according to the invention. In addition to one or more single crystals, the component can also have polycrystalline, in particular finely crystalline, regions.

The component can in particular be a thermally and/or mechanically highly stressed component, preferably a turbine blade. The turbine blade can be provided for land or air based turbines, in particular gas turbines or water turbines. The turbine can be used stationary or mobile. Furthermore, the turbine blade can be used in drives, in particular in engines, or in generators.

Advantageously, the crystal orientation of the single crystals produced using the method according to the invention is optimized by adjusting the direction of expansion, speed and/or temperature of the melted line-shaped area. The crystal orientation, in particular the primary and/or the secondary crystal orientation, can preferably be set very precisely using the method according to the invention. This improves the quality of the production of the monocrystals. The method according to the invention is particularly suitable for components for high-temperature applications, eg with nickel-based alloys, electrical and/or thermal Applications, eg with pure copper or copper alloys, or functional applications, in particular with shape memory alloys, eg nitinol.

Monocrystalline and polycrystalline areas can advantageously be very flexibly combined with one another in the component using the method according to the invention.

Advantageously, the mechanical properties of a component produced by the method according to the invention, in particular of a turbine blade produced by the method according to the invention, can be adapted locally. The local adjustment can take place on the one hand by precisely adjusting the crystal orientation, in particular the primary and/or the secondary crystal orientation, of monocrystalline regions in the turbine blade. On the other hand, these monocrystalline areas in the turbine blade can be surrounded by finely crystalline areas in a precisely defined manner. This advantageously prevents failure of the material of the turbine blade.

The method according to the invention advantageously makes it possible to produce single-crystal components whose crystal orientation is precisely adapted to the load case. In particular, the crystal orientation can be adapted to the course of stress lines and/or lines of force in the component. In addition, the crystal orientation itself in the component can be continuously adapted to the local loads.

In addition, the method according to the invention can also be used to repair and/or supplement monocrystalline components. For example, a broken tip of a monocrystalline component can be restored by the method according to the invention.

According to an advantageous embodiment of the invention, the linear region has a length along its extension direction and a width perpendicular thereto. The ratio of length and width is preferably at least 2:1, preferably at least 5:1 and particularly preferably at least 20:1. By providing such a ratio of length and width of the line-shaped area, a particularly pronounced anisotropy in the mechanical stress field is advantageously produced. This particularly pronounced anisotropy enables the crystal orientation of the single crystal to be produced to be set particularly precisely.

According to a further advantageous embodiment of the invention, the line-shaped area has a width and a depth perpendicular to its direction of extension. The ratio of width and depth is in a range from 1:2 to 10:1, preferably in a range from 2:1 to 4:1. By providing such a ratio of width and depth of the line-shaped area, a particularly high quality of the single crystals produced is advantageously achieved.

According to a further advantageous embodiment of the invention, the depth of the line-shaped area is 50 μm to 1000 μm, preferably 150 μm to 500 μm. The depth of the line-shaped area is preferably dimensioned such that the line-shaped area not only extends within the new layer, but at least partially penetrates into one or more of the layers produced immediately beforehand. As a result, the quality of the single crystals produced can be further increased.

According to a further advantageous embodiment of the invention, the component is produced in layers by local melting of a powder layer made of the metallic material and/or by local application of the metallic material. The component is therefore preferably produced by additive manufacturing. The powder layer can be provided as a bed with the help of a squeegee. The metallic material can be locally applied, for example, by providing a wire or a powder using the method of direct energy deposition. This process is also known by the English name Direct Energy Deposition and the abbreviation DED. In this case, the wire and/or the powder are melted by a focused heat source, for example a laser, an electron beam or an electric arc. The heat source is preferably attached to a gantry system or a robotic arm. This method is particularly advantageous when repairing single-crystal components.

According to a further advantageous embodiment of the invention, the metallic material is melted in the linear area by a laser and/or an electron beam.

The metallic material is preferably heated throughout the new layer by the laser and/or the electron beam during the build-up of the new layer. For this purpose, the laser and/or electron beam sweeps over the new layer, preferably periodically. The laser and/or electron beam can sweep over the new layer several times in predetermined time intervals. The intensity is preferably in the line-shaped area or the dwell time of the laser and/or electron beam is selected in such a way that the metallic material melts.

The method is preferably carried out according to the known methods of selective laser melting, also known by the English designations Selective Laser Melting or Laser Powder Bed Fusion and the abbreviations SLM, LPBF, L-PBF or PBF-L, and/or selective electron beam melting , which is also known by the English names Selective Electron Beam Melting or powder bed fusion electron beam and the abbreviations SEBM or PBF-EB. With this method, the component is built up in layers in a powder bed.

For selective laser melting, the component is preferably built up in layers in a construction space within a process chamber using a powder bed. For this purpose, powder layers made of the metallic material are applied with a squeegee, heated with a laser and selectively melted. The metallic material can be heated so much by multiple scanning with the laser that selective melting takes place. The installation space is preferably brought to a sufficiently high temperature by heating elements so that the metallic material can be selectively melted by the laser. The temperature required for this can be provided in the installation space by heating elements from below, the side or from above. Alternatively or additionally, radiation, for example infrared radiation, can be used for heating from above. The power of the laser is preferably in a range from 50 to 5,000 W. The selective laser melting is preferably carried out under a protective gas atmosphere. The protective gas preferably includes argon, helium and/or nitrogen. Alternatively, selective laser melting in a vacuum be performed. The construction space within the process chamber preferably has a construction plane as the xy plane and a height in the z direction. The dimension of the construction space is preferably 100 to 500 mm in the construction plane and/or 100 to 1000 mm in height. The laser is preferably controlled via actuator-controlled mirrors. The power introduced by the laser into the construction space and in particular into the line-shaped area, into the heat-affected zone and/or into the new layer is preferably modulated by its scanning speed and/or intensity. With pulsed lasers, the pulse frequency can also be varied.

Selective electron beam melting is particularly preferred. The component is preferably built up in layers in a construction space within a vacuum chamber by means of a powder bed. For this purpose, layers of powder are applied with a squeegee, heated by multiple scanning with an electron beam and then selectively melted. The power of the electron beam is preferably in a range from 0.1 to 40 kW. The construction space within the vacuum chamber preferably has a construction level as the x-y plane and a height in the z-direction. The dimension of the construction space is preferably 100 to 500 mm in the construction level and/or 100 to 1000 mm in height. The electron beam is preferably controlled by means of magnetic fields. The electron beam preferably reaches speeds of up to 10,000 m/s. The power introduced by the electron beam into the construction space and in particular into the line-shaped area, into the heat-affected zone and/or into the new layer is preferably modulated by its scanning speed and/or intensity.

The flexibility of the electron beam advantageously allows a temperature field and a temperature-time profile to be set precisely. Thereby the line-shaped area can be generated particularly easily and flexibly. In particular, particularly fine and/or thin structures can be produced for the line-shaped area.

According to a further advantageous embodiment of the invention, the component and/or an installation space containing the component is/are additionally heated.

The component and/or the installation space can also be heated by the laser and/or the electron beam. The heating of the component and/or the installation space can result indirectly from the heating of the new layer and/or the linear area. Alternatively or additionally, the component and/or the installation space can be heated by an external heater. The external heating can be implemented by additional heating units, in particular one or more infrared radiators, one or more inductive heating units and/or one or more resistance heating units.

According to a further advantageous embodiment of the invention, the metallic material, the component and/or the installation space is heated to a temperature in the range from 300° C. to 1200° C., preferably to a temperature in the range from 700° C. to 1200° C., in particular preferably at a temperature in the range of 900°C to 1100°C. In particular when using nickel-based alloys, temperatures in the range from 900° C. to 1100° C. are preferred.

The level of mechanical stress depends on the choice of metallic material and the temperature of the metallic material and/or the component. The mechanical stresses are reduced by plastic strain up to the yield point. The yield point itself depends on the temperature. The method is preferably adjusted in such a way that anisotropic plastic strains of 0.02 to 3%, particularly preferably 0.2 to 1%, are introduced into the material in each layer. Advantageously, the anisotropic plastic strains gradually lead to the formation of a single crystal through texturing.

For nickel-based alloys, the yield stresses are between 1000 MPa and 5 MPa at typical working temperatures of 700°C to 1200°C. It is advantageous to reduce the thermal shrinkage plastically as completely as possible. For this purpose, the temperature of the metallic material and/or the component is preferably so high that the yield point of the metallic material is small compared to the thermomechanical stresses.

According to a further advantageous embodiment of the invention, the layers are built up along a build-up direction. Layers with thicknesses in the range between 10 μm and 500 μm, particularly preferably in the range between 30 μm and 100 μm, are preferably produced here.

According to a further advantageous embodiment of the invention, the metallic material is formed from a nickel-based alloy, nickel-titanium alloy and/or copper alloy.

According to a further advantageous embodiment of the invention, the line-shaped area is subjected to a lateral movement perpendicular to its direction of extension with a lateral velocity v _t while maintaining its direction of extension. The lateral velocity via _t is preferably between 0.1 mm/s and 100 mm/s, particularly preferably between 0.5 and 10 mm/s.

The length of the line-shaped area can vary during this movement. The length of the linear area is preferably varied as a function of a geometry of the component to be produced.

The lateral velocity can be constant at least at times. The lateral velocity at the start of a new layer is preferably equal to zero until the metallic material in the linear area has melted. When traversing the new layer, the lateral velocity is preferably increased to a constant value. Before completing the new layer, the lateral velocity can be decreased again, preferably reaching zero, while the metallic material is allowed to solidify in the linear region.

In particular configurations of the invention, a brief, complete solidification of the metallic material in the line-shaped area can be provided during the build-up of a new layer. The metallic material can then be melted again at the same point or at a different point to create the line-shaped area.

According to a further advantageous embodiment of the invention, a crystal orientation of the monocrystal is set in a defined manner by setting the direction of expansion and lateral movement of the linear region in successive layers. The crystal orientation, in particular the primary and the secondary crystal orientation, is preferably set in a defined manner. The crystal orientation can be adjusted in such a way that it remains constant in the direction of build-up. In particular, the primary and secondary crystal orientations can be adjusted so that they remain constant in the build-up direction. Alternatively, the crystal orientation can be adjusted in such a way that it changes in a defined manner in the build-up direction. In particular, the primary and the secondary crystal orientation can be adjusted in such a way that they change in a defined manner in the direction of build-up, e.g. B. continuously rotate and / or tilt. It should be noted here that the crystal orientation within the single crystal may change. As long as no large-angle grain boundaries occur, one continues to speak of a monocrystal or a "technical monocrystal".

According to a further advantageous embodiment of the invention, the direction of expansion of the line-shaped area in successive layers is the same or rotated by an angle corresponding to a rotational symmetry of the crystal lattice. In the case of a cubic crystal lattice, the direction of extension of the line-shaped region in successive layers is preferably the same or rotated by 90°.

The primary crystal orientation can gradually be tilted in the z-direction, ie in the direction of build-up, as the single crystal grows, in that the direction of extension of the line-shaped region repeatedly remains the same in successive layers.

The crystal orientation, in particular the primary and the secondary crystal orientation, can be kept constant in the z-direction, ie in the direction of construction or in the direction of growth of the single crystal, by the Extension direction of the line-shaped area is rotated in successive layers according to the rotational symmetry of the crystal lattice by, for example, 90 °.

According to a further advantageous embodiment of the invention, the direction of the lateral movement of the line-shaped area is the same in successive layers or rotated by an angle corresponding to a rotational symmetry of the crystal lattice. Preferably, the direction of lateral movement of the line-shaped region in successive layers is the same for a cubic crystal lattice or rotated by 90°, 180° or 270°.

Preferably, the primary crystal orientation is gradually tilted as the single crystal grows in the z-direction, i.e., in the build-up direction, in that the direction of extension of the line-shaped region and the direction of lateral movement of the line-shaped region repeatedly remain the same in successive layers.

The primary crystal orientation can be continuously tilted in the z-direction by 0.01° to 3° per layer, preferably by 0.1° to 2° per layer, particularly preferably by 0.5° to 1° per layer. By repeatedly performing the tilting in successive layers, a total tilting angle of up to 45° relative to the z-direction can preferably be achieved. With a layer thickness of, for example, 50 μm and a tilting of 1° per layer, a total tilting angle of 45° can be achieved during growth of the single crystal can be reached around 2,250 pm in the z-direction. After a desired tilt angle is reached, it is preferred to revert to a fully symmetrical melting strategy, i.e., the primary and/or secondary crystal orientation is preferably kept constant as described below.

The crystal orientation, in particular the primary and the secondary crystal orientation, is preferably kept constant in the z-direction, i.e. in the direction of construction or growth of the single crystal, by changing the direction of extension of the linear region and the direction of the lateral movement of the linear region in successive layers rotated an angle corresponding to a rotational symmetry of the crystal lattice. The direction of extension of the line-shaped area and the direction of the lateral movement of the line-shaped area in successive layers are preferably rotated by 90° in each case in the case of a cubic crystal lattice. The direction of the lateral movement of the line-shaped area is thus preferably rotated by 180° in the next but one layer, by 270° in the third next layer, by 360° in the fourth next layer, and so on.

This procedure is particularly advantageous for cubic crystal systems. This advantageously results in components with an almost exact alignment of the [100] direction in the z direction, for example with a maximum deviation of 1 to 2°. This means a significant improvement over conventional methods. In the case of casting processes, deviations of up to 15° must be tolerated.

It is also advantageous that a component size-dependent single-crystal mosaicism cannot be observed in the method according to the invention. Single crystal mosaicism means that the dendrites within the single crystal are not all aligned in the same way. In the xy plane, the orientation of the single crystal depends on the crystal-plastic properties of the material. For example, for nickel-base alloys, the [100] direction is rotated 45° with respect to the direction of extension of the line-shaped region. The single crystal selection takes place in the range of a few millimeters.

According to a further advantageous embodiment of the invention, the direction of expansion and the direction of the lateral movement of the linear area are rotated by the same angular amount, preferably by 0.01° to 10°, in successive slices, in particular in immediately successive slices, or after a specific number of slices ° per layer, particularly preferably around 0.1 ° to 1 ° per layer.

This allows the crystal orientation, in particular the secondary crystal orientation, to be rotated with respect to the x-y plane, ie the building plane, of the single crystal, preferably continuously by 0.01° to 10° per layer, preferably by 0.1° to 1° per layer , more preferably by 0.3° to 0.7° per layer. The rotation of the single crystal is stress-induced.

In addition, the primary crystal orientation can be kept constant by additionally rotating the direction of extension of the line-shaped region and the direction of lateral movement of the line-shaped region in successive layers by an angle corresponding to a rotational symmetry of the crystal lattice. Preferably, the direction of extension of the line-shaped portion and the direction of lateral movement of the line-shaped portion thereto are in sequential order In the case of a cubic crystal lattice, layers are additionally rotated by 90°. Preferably, the direction of extension and the direction of lateral movement of the line-shaped area in successive slices are thus 90° + 0.01° to 90° + 10° per slice, particularly preferably 90° + 0.1° to 90° + 1° per shift rotated.

According to a further advantageous embodiment of the invention, the direction of expansion of the linear area and/or the lateral movement of the linear area is varied during the build-up of the new layer. In relation to the lateral movement of the line-shaped area, the direction of the lateral movement and/or the magnitude of the lateral speed can be varied.

Alternatively or additionally, the direction of expansion of the line-shaped area and/or the lateral movement of the line-shaped area can be varied in the build-up direction. In relation to the lateral movement of the line-shaped area, the direction of the lateral movement and/or the magnitude of the lateral speed can also be varied. The variation can be provided in the build-up direction in a concrete sequence of successive layers. For example, the variation can be provided in directly consecutive layers or after a specific number of layers.

According to a further advantageous embodiment of the invention, a linear area is melted only in partial areas of the component.

According to a further advantageous embodiment of the invention, monocrystalline and polycrystalline, in particular finely crystalline, areas are formed in the component manufactured. In this case, it is possible for monocrystalline and polycrystalline, in particular finely crystalline, areas to be produced alternately. Monocrystalline and polycrystalline, in particular finely crystalline, areas are preferably produced next to one another. For example, a single-crystal region surrounded by a fine-crystal shell can be produced. The monocrystalline regions are preferably each formed by a monocrystal according to the invention, ie by a monocrystal produced by the method according to the invention.

For example, a turbine blade can be produced from a single crystal surrounded by a finely crystalline shell using the method according to the invention. Such a turbine blade is advantageously characterized by locally adapted mechanical properties. This can be advantageous for fatigue behavior, for example.

According to a further advantageous embodiment of the invention, a continuous change in the crystal orientation is produced in the component, preferably a continuous rotation around the direction of build-up and/or a continuous tilting with respect to the direction of build-up, preferably by 0.01° to 10° per layer, particularly preferably by 0 .1° to 1° per layer.

As already explained above, tilting with respect to the build-up direction relates to the primary crystal orientation and rotation around the build-up direction relates to the secondary crystal orientation.

For metals and alloys that do not solidify in the cubic crystal system, but instead form hexagonal crystals, for example, the above mentioned Construction strategies can be adapted to the symmetry of the lattice in order to produce analogous effects.

According to the invention, a component comprising a single crystal or multiple single crystals with a precisely adjusted primary and/or secondary crystal orientation is also claimed. The component is preferably produced by the method according to the invention. The primary and/or the secondary crystal orientation can be set in such a way that they are constant over the entire monocrystal or over the entire component or in sections. Furthermore, the primary and/or the secondary crystal orientation can be set in such a way that they change, in particular change continuously, over the entire monocrystal or over the entire component or in sections.

The component is preferably a turbine blade. The turbine blade is preferably installed in a gas turbine. The gas turbine is preferably land or air based.

A component according to the invention, in particular a turbine blade according to the invention, advantageously has locally adapted mechanical properties.

The invention will now be explained in more detail using exemplary embodiments. Show it

1 shows a schematic representation of a component being produced with a linear area, Fig. 2 shows a schematic drawing of temperature curves over time,

stress and plastic strain in a heat-affected zone,

3 shows a schematic representation of a formation of a single-crystal component,

Fig. 4 is an experimental example of formation of a single crystal device; Fig. 5 is a schematic drawing with pole figures for describing the

Formation of a single-crystal device and rotation and tilting of the crystal orientation.

1 shows a schematic representation of a component 1 in the open position with a linear area 2. The component 1 is built up in layers from a metallic material in a construction space within a vacuum chamber. To build up a new layer, powder layers made of the metallic material are preferably applied as a powder bed using a doctor blade, heated by multiple scanning with an electron beam and selectively melted in the linear region 2 . The thickness of the new layer is 50 μm, for example. The power of the electron beam is 1 kW, for example. The installation space has an xy plane as the construction level and a z direction as the construction direction. The dimension of the construction space is, for example, 300 mm in the construction plane and 300 mm in the construction direction. The metallic material is melted in the linear area 2 by selective electron beam melting. The linear region 2 has a length L along its direction of extension and a width B and a depth D perpendicular to its direction of extension. The depth D of the line-shaped area is 500 μm, for example. The line-shaped area 2 thus also penetrates into the ten layers produced immediately before the new layer. The width B of the linear area is 1.5 mm, for example. The length L of the line-shaped area is 15 mm, for example. The linear area 2 is surrounded by a heat-affected zone 3 . The metallic material in the heat-affected zone 3 has not melted, more precisely, in part not yet melted, in part no longer melted. In the heat-affected zone 3, a temperature field generated by the electron beam acts in particular on the already solidified metallic material in layers produced immediately before the new layer.

The line-shaped area 2 is moved at a lateral speed vi _at perpendicular to its direction of extension. The lateral velocity vi _at is 5 mm/s, for example.

The melting and subsequent solidification of the metallic material causes plastic deformation of the metallic material in the course of thermally induced mechanical stresses. The mechanical stresses are generated in a targeted manner by adjusting the direction of expansion, speed and temperature of the line-shaped area. The mechanical stresses exceed the yield point of the metallic material, particularly in the linear area 2 and/or in the heat-affected zone 3 . The mechanical stresses have due to the linear configuration of the linear area on a preferred direction. The mechanical stress field is therefore anisotropic. This anisotropy leads to the production of a single crystal. The crystal orientation, in particular the primary and secondary crystal orientation, can be set precisely by the mechanical stress field generated in a targeted manner by setting the direction of expansion, speed and temperature of the line-shaped area.

2 shows a schematic drawing of the temperature T, the mechanical stress in the y-direction a _yy and the plastic strain in the y-direction s _yy each as a function of the time t in the heat-affected zone 3. The construction temperature is named TB. In the construction level, i.e. in the xy plane, the symmetry is broken with regard to the mechanical stress and the plastic expansion. This symmetry breaking, coupled with the property of crystals to orient themselves in specific directions through plastic deformation, referred to as texture formation, ultimately leads to the controlled orientation of each individual columnar crystal and ultimately the generation of the single crystal.

3 shows a schematic representation of formation of a single crystal device. It visualizes the alignment of individual crystallites at different heights when building a component. The direction of construction 4 is perpendicular to the plane of the paper, ie it runs in the z-direction. The direction of extension of the line-shaped region 2 lies in the plane of the paper and alternates from layer to layer in a first layer parallel to the x-axis, in a second layer parallel to the y-axis, and so on. The direction of movement of the linear region 2 moving with the lateral velocity vi _at perpendicular to its direction of extension changes in the process from layer to layer by 90° clockwise. The primary crystal orientation is already set precisely after a height of a few 100 pm: the individual crystallites are aligned in the z-direction, ie in the [001]-direction. At 1 mm, the secondary crystal orientation is still isotropic. As the overall height increases, each individual crystallite is gradually rotated to an angular position of 45° with respect to the x-axis, which means that the secondary crystal orientation is also set precisely. Between a height of 5 mm and 15 mm, the large-angle grain boundaries (shown with solid lines) disappear. Only small-angle grain boundaries (shown with dashed lines) remain. The crystallites are therefore finally completely fused into a single crystal at a height of 15 mm.

4 shows an experimental example of formation of a single crystal component 1. The specific example is a single crystal nickel-based alloy of the type CMSX-4. It is manufactured by selective electron beam melting. A section of the rod-shaped component 1 is shown in the lower part of FIG. The construction direction 4 represented by an arrow goes from right to left. The gray values show different crystal orientations. High-angle grain boundaries are denoted by black lines. In the upper part of FIG. 4, three excerpts from the rod-shaped component are shown enlarged by way of example. The enlarged section shown on the right refers to the first 2 mm in direction 4. Many different crystal orientations with large-angle grain boundaries in between can still be observed. The enlarged detail shown in the middle relates to a height of about 5 to 7 mm in direction 4 of construction. Here, the crystal orientation has already adjusted in larger areas. The large-angle grain boundaries also dissolve progressive height more and more. The enlarged detail shown on the left refers to a height of about 22 to 24 mm in direction 4. Here the crystal orientation has largely aligned. The high-angle grain boundaries are mostly resolved. The disappearance of the high-angle grain boundaries indicates the merging to form a single crystal.

Fig. 5 shows a schematic drawing with pole figures for describing the formation (a) of a single-crystal device 1 and the rotation (b) of the secondary crystal orientation and the tilting (c) of the primary crystal orientation of the single-crystal device 1. In a left-hand column is a schematically rod-shaped component 1 shown. The build-up direction 4 runs from bottom to top in the z-direction, represented by a vertical arrow in the figure. A pole figure is shown for each of four different heights. The four different heights are each marked by a horizontal arrow. In the next column (a), the single crystal selection is shown, starting from an isotropic distribution in the lowest pole figure up to an expression of precisely defined positions in the top pole figure. In the top pole figure of column (a), a single-crystal state is already precisely set. Starting from this single-crystal state, the secondary crystal orientation can be changed in a targeted manner. The crystal lattice can therefore be rotated in the xy plane. This is visualized in column (b) using four additional pole figures. The bottom pole figure corresponds to the top pole figure of column (a). To rotate the crystal lattice, the scanning direction of the electron beam and thus the direction of expansion of the linear region 2 in the xy plane is rotated by 0.5°+90° per slice, for example. Starting from the state in the bottom pole figure, the secondary crystal orientation in column (b) is successively rotated by 45° up to the top pole figure. In the column (c) then the primary Changed crystal orientation in a targeted manner. The single crystal is tilted in relation to the z-direction. This is visualized in column (c) using four additional pole figures. The bottom pole figure corresponds to the top pole figure of column (b). The tilting of the monocrystal occurs through symmetry breaking. A symmetry break can be achieved in that the direction of extension of the linear region 2 and its direction of movement remain the same in successive layers.

Even if the sections in which the component 1 does not yet have a monocrystalline state in an initial phase of the production process are referred to as component 1, it goes without saying that preferably only the sections after the monocrystal selection finally form the component 1. For this purpose, the sections from the initial phase of the manufacturing process can be separated from the component 1.

LIST OF REFERENCE NUMERALS 1 Component

2 linear area

3 heat affected zone

4 assembly direction L length

B width

D depth a _yy mechanical stress in y-direction s _yy plastic strain in y-direction T temperature

TB build temperature

Claims

Expectations

1. A method for producing a component (1) by building up layers by combining a multiplicity of crystallites of a metallic material to form a single crystal, the single crystal being formed by thermo-mechanically activated successive anisotropic plastic deformation, the metallic material during the construction of a new Layer is heated so that the metallic material is melted in a linear region (2), and wherein the structure of the new layer of the linear region (2) is moved.

2. The method according to claim 1, wherein the linear region (2) has a length (L) along its extension direction and a width (B) perpendicular thereto, and wherein the ratio of length (L) and width (B) is preferably at least 2: 1, preferably at least 5:1 and more preferably at least 20:1.

3. The method according to claim 1 or 2, wherein the line-shaped region (2) has a width (B) and a depth (D) perpendicular to its direction of extension, and wherein the ratio of width (B) and depth in one range from 1:2 to 10:1, preferably in a range from 2:1 to 4:1.

4. The method according to any one of the preceding claims, wherein the depth (D) of the linear region (2) is 50 μm to 1000 μm, preferably 150 μm to 500 μm.

5. The method according to any one of the preceding claims, wherein the component (1) is produced in layers by locally melting a powder layer of the metallic material and / or by local application of the metallic material.

6. The method according to any one of the preceding claims, wherein the metallic material in the linear region (2) is melted by a laser and / or an electron beam.

7. The method according to any one of the preceding claims, wherein in addition the component (1) and / or the component (1) containing space is heated.

8. The method according to any one of the preceding claims, wherein the metallic material, the component (1) and / or the installation space is heated to a temperature (T) in the range of 300 ° C to 1200 ° C, preferably to a temperature (T) in the range from 700°C to 1200°C, particularly preferably to a temperature (T) in the range from 900°C to 1100°C.

9. The method according to any one of the preceding claims, wherein the layer structure takes place along a structure direction (4) and preferably Layers with thicknesses in the range between 10 gm and 500 gm, particularly preferably in the range between 30 gm and 100 gm, are produced.

10. The method according to any one of the preceding claims, wherein the metallic material is formed from a nickel-based alloy, nickel-titanium alloy and / or copper alloy.

11. The method according to any one of the preceding claims, wherein the linear region (2) is subjected to a lateral movement perpendicular to its direction of extension at a lateral speed vi _at while maintaining its direction of extension, the lateral speed vi _at preferably being between 0.1 mm/s and 100 mm /s, particularly preferably between 0.5 and 10 mm/s.

12. The method according to claim 11, wherein a crystal orientation of the monocrystal is set in a defined manner by setting the direction of expansion and lateral movement of the line-shaped region (2) in successive layers.

13. The method according to any one of the preceding claims, wherein the direction of extension of the linear region (2) in successive layers is the same or is rotated by an angle corresponding to a rotational symmetry of the crystal lattice, the direction of extension of the linear region (2) in successive layers being cubic Crystal lattice is preferably the same or rotated by 90 °.

14. The method according to any one of the preceding claims, wherein the direction of lateral movement of the line-shaped region (2) is the same in successive layers or is rotated by an angle corresponding to a rotational symmetry of the crystal lattice, the direction of lateral movement of the line-shaped region (2) in successive layers Layers in a cubic crystal lattice is preferably the same or rotated by 90 °, 180 ° or 270 °.

15. The method according to any one of the preceding claims, wherein the direction of expansion and the direction of the lateral movement of the linear region (2) are rotated by the same angular amount in successive slices or after a certain number of slices, preferably by 0.01° to 10° per layer, more preferably around 0.1° to 1° per layer.

16. The method according to any one of the preceding claims, wherein the direction of extension of the linear area (2) and/or the lateral movement of the linear area (2) is varied during the build-up of the new layer, and/or wherein the direction of extension of the linear area (2) and/or the lateral movement of the linear area (2) is varied in the build-up direction (4).

17. The method according to any one of the preceding claims, wherein a linear region (2) is melted only in partial regions of the component (1).

18. The method according to any one of the preceding claims, wherein monocrystalline and polycrystalline areas are produced in the component (1).

19. The method according to any one of the preceding claims, wherein a continuous change in the crystal orientation is produced in the component (1), preferably a continuous rotation about the direction of construction (4) and / or a continuous tilting with respect to the direction of construction (4), preferably by 0, 01° to 10° per layer, more preferably around 0.1° to 1° per layer.

20. A component comprising a single crystal with a precisely adjusted primary and/or secondary crystal orientation, preferably produced by a method according to one of the preceding claims.