EP3883708A1

EP3883708A1 - Additively-manufactured refractory metal component, additive manufacturing process, and powder

Info

Publication number: EP3883708A1
Application number: EP19787135.3A
Authority: EP
Inventors: Karl-Heinz LEITZ; Heinrich Kestler; Peter Singer; Gerhard Leichtfried; Jakob BRAUN; Lukas KASERER; Janko STAJKOVIC
Original assignee: Plansee SE
Current assignee: Plansee SE
Priority date: 2018-11-19
Filing date: 2019-10-03
Publication date: 2021-09-29
Also published as: WO2020102834A1; US20220016699A1; JP7397869B2; KR20210091750A; CN113039028B; AT16308U2; CN113039028A; AT16308U3; TW202020178A; JP2023156376A; TWI810385B; JP2022507758A; KR102530699B1

Abstract

The invention relates to a component having a matrix phase consisting of at least one material selected from a group comprising molybdenum, a molybdenum-based alloy, tungsten, a tungsten-based alloy and a molybdenum-tungsten based alloy, manufactured by a laser- or electron beam in an additive manufacturing process, the molybdenum content, tungsten content, or the total content of molybdenum and tungsten being greater than 85 at%, and the component containing particles, the melting point of which lies above the melting point of the matrix phase.

Description

Additively manufactured refractory metal component,

additive manufacturing process and powder

The invention relates to a component with the features of the preamble of claim 1, an additive manufacturing process for producing a component with the features of the preamble of claim 9 and a use of a powder for an additive manufacturing process.

Due to the high melting point, the low coefficient of thermal expansion and the high thermal conductivity, tungsten, molybdenum and their alloys are used for various high-performance applications, such as for X-ray anodes, heat sinks, high-temperature heating zones, thrusters, extrusion matrices, molded parts for injection molding, hot runner nozzles, resistance welding electrodes or Components used for ion implantation systems. In addition, these elements have a high density, which ensures good shielding behavior against electromagnetic and particle radiation. Due to the comparatively low ductility at room temperature and the high DBTT (Ductile Brittle Transition Temperature), the processing properties are unfavorable for both cutting and non-cutting processes. In addition, with the exception of molybdenum rhenium and tungsten rhenium, the weldability of these materials is poor. A large-scale process for the production of components from these materials is the powder metallurgical production route, in which the corresponding starting powders are pressed and sintered and are usually subsequently shaped at a high temperature (temperature greater than DBTT).

The possibilities for geometrical component design that can be achieved with additive manufacturing processes far exceed those of conventional processes. In the case of materials such as molybdenum, tungsten and their alloys in particular, the additive manufacturing process is particularly advantageous since, compared to other metallic materials, these materials are much more difficult to machine with conventional manufacturing methods. In the additive manufacturing of metallic materials, mostly powders, less often wires, are used as Starting material used. For metallic materials, several processes have been established, such as selective laser sintering (SLS), in which layered powder is sintered locally using a laser beam, selective laser beam melting (SLM) and selective electron beam melting (SEBM), in which layered powder is locally melted, and laser Metal deposition (LMD), in which a powder fed through a nozzle is melted.

Additive manufacturing processes do not require any cutting or shaping tools, which enables low-cost production of components. In addition, high resource efficiency is achieved because powder particles that have not melted or sintered together can be reused. A disadvantage of these processes is currently the very low build-up rate.

In addition, with beam-based additive manufacturing processes, it must be taken into account that, compared to conventional consolidation processes such as casting or sintering, other metal-physical mechanisms are effective. While surface and grain boundary diffusion determine the compaction during sintering, processes that involve local melting and solidification with a high cooling rate, such as SLM, SEBM and LMD, have different mechanisms of action, which are significantly more complex and not yet fully understood. Wetting behavior, Marangoni convection, recoil effects due to evaporation, segregation, epitaxial grain growth, solidification time, heat flow, heat flow direction and internal stresses as a result of solidification loss should be mentioned. Material concepts that are successful in conventional processes usually do not lead to faultless components in beam-based additive processes.

The production of pure tungsten via selective laser beam melting is described in an article by Dianzheng Wang et al. (Appl. Sci. 2007, 7, 430), the production of molybdenum via selective laser beam melting in a technical article by D. Faidel et al. (Additive Manufacturing 8 (2015) 88-94). WO 2012/055398 discloses a selective laser beam melting process for refractory metals, the composition of the material being changed by reaction with a reactive gas contained in the atmosphere during the construction of the component can. In the document CN 103074532 A and the associated article “Selective Laser Melting Additive Manufacturing of Hard-to-Process Tungsten-Based Alloy Parts With Novel Crystalline Growth Morphology and Enhanced Performance”, Journal of Manufacturing Science and Engineering, August 2016, Vol. 138 , 081003, by Dongdong Gu et al. , the laser melting of mechanically alloyed tungsten-TiC powder is described. SK Makineni et al. describe in "Synthesis and stabilization of a new phase regime in a Mo-Si-B based alloy by laser-based additive manufacturing", Acta Materialia 151 (2018), 31 40 the manufacture of a molybdenum-based alloy using grain-refining lanthanum oxide nanoparticles .

US 2018/0214949 A1 and WO 2018/144323 show the use of grain-refining nanoparticles for the production of powders for additive manufacturing, which contain particles made of an aluminum alloy.

The most common additive manufacturing process is the selective laser beam melting process (SLM). Here, a powder layer is applied to a surface using a doctor blade. A laser beam is then passed over this layer of powder. This melts the powder particles locally, as a result of which the individual powder particles melt together and with the previously applied layer. A layer of the component to be manufactured is thus created by successive local melting of powder particles and subsequent solidification. Another layer of powder is then applied to the already processed layer of powder and the process begins again. The component is thus built up with each new powder layer, the direction of construction being arranged normal to the respective levels of the powder layers. Since the additive manufacturing process forms a characteristic microstructure, it is possible for the person skilled in the art to recognize whether a component is manufactured by a conventional process or by an additive manufacturing process.

Molybdenum and tungsten have a high melting point, high thermal conductivity in the solid phase and high surface tension and viscosity in the liquid phase. These materials are among the most difficult to process using an additive manufacturing process. The short time in the molten phase due to the high thermal conductivity combined with the high surface tension and the high viscosity favor the balling effect, which in turn leads to pores and thus to crack-causing defects and a low density. The balling effect also has a negative effect on the surface quality, especially on the surface roughness. Since molybdenum and tungsten have a very low fracture toughness, local defects, combined with the inherent, thermally induced stresses inherent in the process, lead to cracks.

Components made of molybdenum and tungsten produced by selective laser or electron beam melting show a stem-crystalline structure, whereby the average grain aspect ratio (Grain Aspect Ratio - GAR value; ratio of grain length to grain width) is typically greater than 8 in the direction of assembly. In the plane normal to the direction of construction, an intercrystalline crack network is formed, which depicts the melting trace of the laser or electron beam. The cracks are mainly intergranular hot and cold cracks. These are partially connected to each other, which means that components often have open porosity and are not sealed against gases and liquids. If the component is subjected to stress, there is generally no plastic deformation and intercrystalline fracture behavior is predominantly observed. An intergranular fracture behavior is a fracture that is mainly caused by cracks along the grain boundaries. Due to this fracture behavior, components manufactured in this way have low fracture strength, low fracture toughness and low ductility.

The object of the invention is to provide

a generic component, the molybdenum content, the tungsten content or the total content of molybdenum and tungsten being greater than 85 at%, in which the problems discussed above are avoided

- A generic additive manufacturing process for the reliable production of a component with the aforementioned properties using a starting powder, wherein the molybdenum content, the tungsten content or the total content of molybdenum and tungsten is greater than 85 at%

- And a powder, which shows optimized behavior for use in an additive manufacturing process, the powder consisting of particles at least one material selected from a group comprising molybdenum, a molybdenum-based alloy, tungsten, a tungsten-based alloy and a molybdenum-tungsten-based alloy, wherein the particles have a matrix phase and wherein the molybdenum content, the tungsten content or the total content of molybdenum and tungsten is greater than 85 at%.

In particular, it is the object of the invention to provide a component which has the following properties:

- Reduced frequency of errors, especially cracks

- improved strength

- improved fracture toughness

- improved ductility

- improved density

This object is achieved by a component with the features of claim 1, an additive manufacturing method with the features of claim 9 and the use of a powder with the features of claim 14. Advantageous embodiments of the invention are defined in the dependent claims.

In the present disclosure, a powder is understood to mean a collection of particles. The particles can e.g. B. as a volume component of particles of the powder (in particular, for example, in the form of precipitates), as particles adhering to the surface of particles of the powder or as components of the powder which are present separately from the particles.

Molybdenum-based alloy is an alloy that contains at least 50 at% molybdenum. A molybdenum-based alloy for use in the invention has at least 85, 90, 95 or 99 at% molybdenum. A tungsten based alloy contains at least 50 at% tungsten. A tungsten-based alloy for use in the invention has at least 85, 90, 95 or 99 at% tungsten. A molybdenum-tungsten alloy is understood to mean an alloy which contains at least 50 at% molybdenum and tungsten in total, in particular at least 80, 90, 95 or 99 at% molybdenum and tungsten in total. Molybdenum-tungsten alloys are a preferred embodiment in all concentration ranges.

Typically, components made of molybdenum, tungsten, molybdenum and tungsten-based alloys produced using beam-based additive manufacturing processes have an oxygen content of between 0.25 and 0.6 at%. When using mechanically alloyed starting powders, significantly higher oxygen contents of 2 at% and above can also occur. The oxygen content is not reduced by the additive manufacturing process, such as selective laser or electron beam melting. When using high-resolution examination methods such as grid or

Transmission electron microscopy shows that in components according to the prior art, the oxygen is predominantly excreted at the grain boundaries in the form of molybdenum or tungsten oxide. These precipitations are responsible for the intergranular fracture behavior with consequently low fracture strength and toughness of additively manufactured components made of molybdenum, tungsten and their alloys. The high oxygen content can cause both hot and cold cracks. Hot cracks occur during manufacture due to a reduced grain boundary strength. In the given case, the grain boundary strength in the heat-affected zone of the melting trace is adversely affected by the melting of the oxides deposited at the grain boundaries. Cold cracks are due to thermally induced stresses in connection with defects (pores, micro cracks), which act as crack nuclei. If the grain boundary strength is clearly lower than the strength inside the grain, as is the case with the prior art, an intercrystalline crack pattern occurs.

A high oxygen content also increases the balling effect. The oxygen is enriched in the edge area of the melting zone and reduces the surface tension there. Marangoni convection thus favors a material flow from the edge area into the center of the melting zone, which significantly increases the balling triggered by the Plateau-Rayleigh instability. The basic idea of the invention is to use the particles whose melting point is above the melting point of the matrix phase and which can thus act as crystallization nuclei for the melted matrix phase to achieve a fine-grained structure of the component. With a fine-grain structure, the total grain boundary area in the component is larger than with a coarse-grain structure, so that the oxides formed with the molybdenum or tungsten are distributed over a larger area without the oxygen content of the component having to be reduced. A weakening of the grain boundaries can thereby be avoided. In addition, a fine-grain structure leads to an increase in toughness.

In principle it is possible to adjust grain refinement by constitutional hypothermia. However, in order to achieve a sufficient effect, high levels of alloying elements are required, which cause constitutional hypothermia. These high contents cause an increase in strength, e.g. B. by mixed crystal formation or precipitates, whereby the ductility, expressed z. B. is significantly reduced by the fracture toughness. By providing particles according to the invention with a melting point above the melting point of the matrix phase, it is possible to achieve a grain-refining effect without constitutional hypothermia or with a lower content of alloying elements which cause constitutional hypothermia.

A component according to the invention is characterized in that the component contains particles whose melting point is above the melting point of the matrix phase. As already described, these particles lead to a fine-grained structure in the component and thus increase strength and toughness.

The material used, from which the component is made, is preferably a powder.

The presence of the particles is verified by conventional metallographic methods, for example by scanning or transmission electron microscopy. An additive manufacturing process according to the invention is characterized in that the starting powder

- Contains particles whose melting point is above the melting point of the matrix phase, and / or

- Contains at least one precursor substance (e.g. zirconium, hafnium, tantalum, titanium, niobium, vanadium) for particles, the melting point of the particles being above the melting point of the matrix phase and the particles from the precursor substance being melted together in layers by means of the particles of the starting powder Lasers or electron beams are created

- Contains at least one component (e.g. zirconium, hafnium, tantalum, titanium, niobium, vanadium) which, in reaction with at least one component of a process gas atmosphere (e.g. nitrogen) when the particles of the starting powder are melted together in layers by means of laser or electron beam Forms particles whose melting point is above the melting point of the matrix phase

It is preferably provided that the step of providing a starting powder comprises spheroidizing in the melting phase and / or granulating a raw powder.

All additive manufacturing processes known according to the prior art, in particular those in which a large number of individual powder particles are melted together by a high-energy beam (laser or electron beam) to form a solid structure, can be used in the invention.

A powder for use according to the invention in an additive manufacturing method, in particular an additive manufacturing method according to the invention, is characterized in that the powder

- Contains particles whose melting point is above the melting point of the matrix phase of the particles, and / or

contains at least one precursor substance for particles, the melting point of the particles being above the melting point of the matrix phase of the particles and the particles arising from the precursor substance when the particles of the starting powder are melted together in layers by means of laser or electron beam The individual powder particles are preferably melted using an additive manufacturing process, SLM (selective laser beam melting) or SEBM (selective electron beam melting) advantageously being used.

The component is preferably built up in layers. For example, a powder layer is applied to a base plate using a doctor blade. The powder layer usually has a height of 10 to 150 pm.

With the SEBM, the powder particles are first sintered together with a defocused electron beam. Subsequently, the powder is melted locally by energy input using an electron beam. With the SLM, the powder can be locally melted using a laser beam.

The jet creates a cellular weld pool with a line width of typically 30 microns to 200 microns. The laser or electron beam is guided over the powder layer. The entire powder layer or only part of the powder layer can be melted and subsequently solidified by suitable beam guidance. The melted and solidified areas of the powder layer are part of the finished component. The unmelted powder is not part of the manufactured component. A further layer of powder is then applied by means of a doctor blade and the laser or electron beam is again guided over this layer of powder. This creates a layered structure and a characteristic component structure. By guiding the electron or laser beam, a so-called scan structure is formed in each powder layer. Furthermore, a typical layer structure also forms in the direction of construction, which is determined by the application of a new powder layer. Both the scan structure and the individual layers can be recognized on the finished component.

The structure of powder particles melted together selectively to form a solid structure by means of an additive manufacturing process by means of an energy-rich beam (preferably by means of a laser or electron beam) differs significantly from that produced by other processes, for example thermal spraying Structure. In thermal spraying, individual spray particles are accelerated in a gas stream and hurled onto the surface of the component to be coated. The spray particles can be in the form of melted or melted (plasma spraying) or solid (cold gas spraying). A layer formation takes place because the individual spray particles flatten out when they hit the component surface, stick mainly through mechanical clamping and build up the spray layer in layers. A plate-like layer structure is formed. Layers produced in this way have a grain stretching perpendicular to the building direction in a plane parallel to the building direction with an average grain stretching ratio (Grain Aspect Ratio - GAR value; ratio of grain length to grain width) well above 2 and thus differ significantly from layers produced by selective laser or electron beam melting / Components that have an average grain stretching ratio well above 2 in a plane parallel to the direction of assembly, but with a grain stretching parallel to the direction of assembly.

In one exemplary embodiment of a component according to the invention it is provided that the content of the component in the particles is so high that the matrix phase has an average grain area of less than 10,000 square micrometers, preferably less than 5000 square micrometers, particularly preferably less than 2500 square micrometers.

In one embodiment of a component according to the invention and / or the manufacturing method according to the invention and / or the use according to the invention it is provided that an average size of the particles is less than 5 micrometers, preferably less than 1 micrometer. The average size of the particles is preferably greater than 10 nanometers.

In one exemplary embodiment of a component according to the invention and / or of the production method according to the invention, it is provided that the volume content of the particles in the component is between 0.05% by volume and 10% by volume. The grain-refining effect is not sufficient below 0.05% by volume, and the particle number A / olumen (responsible for the resulting grain size) increases only slightly above 10% by volume, so that volume contents greater than 10% by volume essentially only cause coarsening of the particles , but not a further reduction in Grain size. However, these higher volume levels lead to a loss of ductility.

The volume content can be measured in various ways, of which the following are mentioned as examples:

- Determination of the composition of the particles and any dissolved proportions of the elements forming the particles by suitable analysis methods such as XRD, REM / EDX, TEM / EDX, microsensor

- Determination of the total content of the elements forming the particles by suitable methods such as ICP-OES, ICP-MS or RFA

- Calculation of the particle content (dissolved parts of the elements forming the particles are not taken into account)

In one exemplary embodiment of a component according to the invention, it is provided that the component has a fracture behavior at least in a fracture plane with a transcrystalline fraction of more than 50%, preferably more than 80%, particularly preferably more than 90%, of the fracture surface.

In one exemplary embodiment of a component according to the invention, it is provided that the component is manufactured in layers in one direction of construction and preferably has an average grain extension in a plane parallel to the direction of construction less than 5, preferably less than 3. The low grain stretching ensures an isotropy of the mechanical properties which is sufficient for the customarily required use properties.

In one embodiment of a component according to the invention and / or an additive manufacturing method according to the invention and / or a use of a powder according to the invention it is provided that the particles are selected individually or in any combination from a group comprising:

- Oxides, preferably Zr0 ₂

- carbides, preferably ZrC, NbC, MoC, TiC, TaC, HfC

- nitrides, preferably YN, TaN, HfN

- Borides, preferably TaB ₂ , HfB ₂ Which type of particle is preferred depends on what the matrix phase of the component consists of. It is important to ensure that the melting point of the particles is above the melting point of the matrix phase of the component.

The melting temperatures of the above compounds:

YN (T _m = 2670 ° C), MoC (T _m = 2687 ° C), Zr0 ₂ (T _m = 2715 ° C), Ta (T _m = 2996 ° C), TaN (T _m = 3090 ° C) , TaB ₂ (T _m = 3140 ° C), TiC (T _m = 3160 ° C), Re (T _m = 3180 ° C), HfB ₂ (T _m = 3250 ° C), HfN (T _m = 3305 ° C), TaC (T _m = 3880 ° C), HfC (T _m = 3900 ° C), ZrC (T _m = 3540 ° C), NbC (T _m = 3500 ° C) are above the melting temperature of molybdenum (T _m = 2623 ° C) and partly above that of tungsten (T _m = 3422 ° C).

With regard to the use of a powder according to the invention, it is preferably provided that the powder has a particle size of less than 100 micrometers.

With regard to the use of a powder according to the invention, a

Embodiment provided that the particles of the powder have the particles, preferably in the form of fine precipitates. The advantage of this is that there can be no disadvantageous segregation when doctoring the powder layer.

With regard to the use of a powder according to the invention, a

Embodiment provided that the powder is a mixture containing particles containing molybdenum and / or tungsten and particles whose melting point is above the melting point of the matrix phase. The advantage here is that the raw materials are easily available.

With regard to the use of a powder according to the invention, a

Embodiment provided that the at least one precursor for the Particles whose melting point is above the melting point of the matrix phase are at least partially present as a layer on particles of the powder.

In one embodiment of the component according to the invention it is provided that the component has one or more alloy elements, the or the

in the case of molybdenum and the molybdenum-based alloy for M0O ₂ and / or M0O ₃

in the case of tungsten and the tungsten-based alloy for WO ₂ and / or WO ₃ and

in the case of the molybdenum-tungsten-based alloy for at least one oxide from the group M0O ₂ , M0O ₃ , WO ₂ and WO ₃

has or has a reducing effect at least in the temperature range> 1500 ° C., at least one of the alloy elements being present both in at least partially non-oxidized form and in oxidized form.

In one embodiment of an additive manufacturing method according to the invention, it is provided that the starting powder provided has at least one element which in the case of molybdenum and the molybdenum-based alloy for M0O ₂ and / or M0O ₃ , in the case of tungsten and the tungsten-based alloy for WO ₂ and / or WO ₃ and in the case of the molybdenum-tungsten-based alloy for at least one oxide of the group M0O ₂ , M0O ₃ , WO ₂ and WO _{3 has a} reducing effect at least in the temperature range> 1500 ° C. and in the starting powder provided in at least partially non-oxidized form is present and that at least one of the reducing elements is at least partially present as an oxide in the component produced.

In one exemplary embodiment of a powder according to the invention, it is provided that the powder further comprises one or more elements, which in the case of molybdenum and the molybdenum-based alloy for M0O ₂ and / or M0O ₃ , in the case of tungsten and the tungsten -based alloy for WO ₂ and / or WO ₃ and in the case of the molybdenum-tungsten-based alloy for at least one oxide of the group M0O ₂ , M0O ₃ , WO ₂ and WO ₃ reducing at least in the temperature range> 1500 ° C. acts or act, and that at least one reducing element is present in at least partially non-oxidized form.

The measures described above make it possible to reduce the formation of molybdenum or tungsten oxides, in particular at the grain boundaries, by offering the oxygen in the form of the reducing effect of at least one alloy element or reducing element a more attractive reaction partner. It is therefore not the oxygen content of the component that is reduced, but rather the oxygen is at least partially, preferably largely, in a solid oxide form (at room temperature) formed with the alloy element (s). The oxygen bound in this way can no longer have an adverse effect on the grain boundary strength.

Suitable reducing alloying elements or reducing elements can easily be found by the person skilled in the art in tables.

With the help of Gibb’s energy (free enthalpy) or with the help of the Richardson-Ellingham diagram, the elements that have a reducing effect on molybdenum or tungsten oxide can be found on the basis of the differences between their free standard enthalpies of formation. This makes it possible in a simple manner to find elements which are suitable as reducing agents for molybdenum or tungsten oxide. The alloying element preferably has a reducing effect for all molybdenum oxides (e.g. M0O2, M0O3) or for all tungsten oxides (e.g. WO2, WO3), regardless of their stoichiometry. So that the alloy element can reliably bind the oxygen in the form of an oxide, the alloy element must have a reducing effect for molybdenum and / or tungsten oxide at least in the temperature range> 1500 ° C. At temperatures <1500 ° C, the reaction kinetics are too low, so that re-oxidation of molybdenum or tungsten no longer occurs. The alloying element preferably has a reducing effect in the temperature range from room to liquidus temperature for molybdenum and / or tungsten oxide.

It is preferably provided that at least one of the alloying elements is an element from group 2, 3 or 4 of the periodic table, preferably titanium, zirconium or Hafnium. For example, it can be provided that the component contains HfC, ZrC> 2 or Hf0 ₂ .

The proof that the alloying element is present in the component in at least partially non-oxidized and in oxidized form can be done by conventional methods, such as XRD, micro-probe, ICP-OES, ICP-MS, RFA, REM / EDX, TEM / EDX and carrier gas hot extraction . The quantitative determination of the alloying element content takes place, for example, via ICP-OES or ICP-MS, the quantitative determination of the oxygen content by means of hot gas extraction or XRF. Whether the alloying element is present both in oxidized form and in non-oxidized form can be determined by XRD and, in the case of low contents, by spatially resolving methods, such as, for example, microsonde, REM / EDX or TEM / EDX.

It can preferably be provided that the particles whose melting point is above the melting point of the matrix phase themselves act as these alloying elements or reducing elements, that is to say they assume a double role.

Claims

1. Component with a matrix phase made of at least one material, selected from a group comprising molybdenum, a molybdenum-based alloy, tungsten, a tungsten-based alloy and a molybdenum-tungsten-based alloy, which is produced by means of laser or electron beam in an additive manufacturing process is, the molybdenum content, the tungsten content or the total content of molybdenum and tungsten is greater than 85 at%, characterized in that the component contains particles whose melting point is above the melting point of the matrix phase.

2. The component according to claim 1, wherein the content of the component in the particles is so high that the matrix phase has an average grain area of less than 10,000

Has square micrometers, preferably less than 5000 square micrometers, particularly preferably less than 2500 square micrometers.

3. Component according to at least one of the preceding claims, wherein an average particle size of the particles is less than 5 micrometers.

4. Component according to at least one of the preceding claims, wherein a

Volume content of the particles in the component is between 0.05 vol% and 10 vol%.

5. The component according to at least one of the preceding claims, wherein the component has at least in a fracture plane a fracture behavior with a transcrystalline fraction of more than 50% of the fracture surface.

6. Component according to at least one of the preceding claims, wherein the component was manufactured in an additive manufacturing process along a direction of construction and wherein an average grain stretching in a plane parallel to the direction of construction is less than 5.

7. Component according to at least one of the preceding claims, wherein the particles are selected individually or in any combination from a group comprising:

- Oxides, preferably Zr0 ₂ , Hf0 ₂

- carbides, preferably ZrC, NbC, MoC, TiC, TaC, HfC

- nitrides, preferably YN, TaN, HfN

- Borides, preferably TaB ₂ , HfB ₂

8. The component according to at least one of the preceding claims, wherein the component (8) has one or more alloy elements, the or

- in the case of molybdenum and the molybdenum-based alloy for M0O ₂ and / or M0O ₃

- In the case of tungsten and the tungsten-based alloy for WO ₂ and / or WO ₃ and

- In the case of the molybdenum-tungsten-based alloy for at least one oxide from the group M0O ₂ , M0O ₃ , WO ₂ and WO ₃

9. Additive manufacturing method for producing a component, in particular a component according to at least one of the preceding claims, comprising at least the following steps:

- Providing a starting powder from at least one material selected from a group comprising molybdenum, a molybdenum-based alloy, tungsten, a tungsten-based alloy and a molybdenum-tungsten-based alloy

- Layer-wise melting together of the particles of the starting powder by means of laser or electron beam, whereby a matrix phase is formed, the molybdenum content, the tungsten content or the total content of molybdenum and tungsten in the matrix phase being greater than 85 at%

characterized in that the starting powder - Contains particles whose melting point is above the melting point of the matrix phase, and / or

contains at least one precursor substance for particles, the melting point of the particles being above the melting point of the matrix phase and the particles arising from the at least one precursor substance when the particles of the starting powder are melted together in layers by means of laser or electron beam, and / or

- Contains at least one component which forms particles in reaction with at least one component of a process gas atmosphere when the particles of the starting powder are melted together in layers, the melting point of which is above the melting point of the matrix phase

10. The manufacturing method according to the preceding claim, wherein the step of providing the starting powder comprises spheroidizing in the melting phase and / or granulating a raw powder.

11. Manufacturing method according to at least one of the two preceding claims, wherein an average size of the particles is less than 5 microns.

12. Manufacturing method according to at least one of the preceding claims, wherein a volume content of the particles in the component is between 0.05 vol% and 10 vol%.

13. The production method according to at least one of the preceding claims, wherein the starting powder provided has at least one element which in the case of molybdenum and the molybdenum-based alloy for M0O2 and / or M0O3, in the case of tungsten and the tungsten-based alloy for WO2 and / or WO3 and in the case of the molybdenum-tungsten-based alloy for at least one oxide of the group M0O2, M0O3, WO2 and WO3 has a reducing effect at least in the temperature range> 1500 ° C. and is present in the starting powder provided in at least partially non-oxidized form and that in produced component (8) is at least partially present as an oxide at least one of the reducing elements.

14. Use of a powder which comprises particles of at least one material selected from a group comprising molybdenum, a molybdenum-based alloy, tungsten, a tungsten-based alloy and a molybdenum-tungsten-based alloy, the particles having a matrix phase and wherein the molybdenum content, the tungsten content or the total content of molybdenum and tungsten in the matrix phase is greater than 85 at%, characterized in that the powder

contains at least one precursor substance for particles, the melting point of the particles being above the melting point of the matrix phase of the particles and the particles arising from the at least one precursor substance when the particles of the starting powder are melted together in layers by means of laser or electron beam

and is used for an additive manufacturing process, in particular for an additive manufacturing process according to at least one of the preceding claims.

15. Use of a powder according to the preceding claim, wherein the

Particles of powder are the particles, preferably in the form of fine

Excretions.

16. Use of a powder according to at least one of the preceding

Claims, wherein the powder is a mixture containing particles containing molybdenum, a molybdenum-based alloy, tungsten, a tungsten-based alloy or a molybdenum-tungsten-based alloy and particles whose melting point is above the melting point of the matrix phase.

17. Use of a powder according to at least one of the preceding

Claims, wherein the at least one precursor for the particles, the Melting point is above the melting point of the matrix phase, is at least partially present as a layer on particles of the powder.

18. Use of a powder according to at least one of the preceding claims, wherein an average particle size of the particles whose melting point is above the melting point of the matrix phase of the particles is less than 5 micrometers.

19. Use of a powder according to at least one of the preceding claims, wherein a volume content of the particles whose melting point is above the melting point of the matrix phase of the particles in the powder is between 0.05 vol% and 10 vol%.

20. Use of a powder according to at least one of the preceding claims, wherein the powder further comprises one or more elements, which in the case of molybdenum and the molybdenum-based alloy for M0O2 and / or M0O3, in the case of tungsten and Tungsten-based alloy for WO2 and / or WO3 and in the case of the molybdenum-tungsten-based alloy for at least one oxide of the group M0O2, M0O3, WO2 and WO3 has or has a reducing effect at least in the temperature range> 1500 ° C., and at least one reducing one Element is present in at least partially unoxidized form.