Method for generating a component by a power-bed-based additive manufacturing method and powder for use in such a method
The disclosure relates to a powder and a method for generating a component by a powder-bed-based additive manufacturing method, such as laser melting. The powder includes particles having a core and a shell. The particles have an alloy composition of the component. The concentration of higher-melting alloy elements is greater in the shell and the concentration of lower-melting alloy elements is greater in the core, wherein the surface of the particles is higher in comparison with particles with a constant alloy composition. This advantageously prevents the particles from caking together in the powder bed during the production of the component, and so the powder bed may also be subjected to high preheating temperatures of up to 1000° C.
1. A method for generating a component by powder-bed-based additive production, the method comprising:
providing a powder having a plurality of particles, wherein each particle of the powder comprises a core and shell, wherein the core of each particle comprises a first metallic alloy composition having at least 50 mass % nickel, wherein the shell comprises a second metallic alloy composition having a different composition than the first metallic alloy composition, wherein the second metallic alloy composition comprises cobalt, iron, chromium, molybdenum, tantalum, tungsten, or combinations thereof, and wherein a melting temperature of the first metallic alloy composition is lower than a melting temperature of the second metallic alloy composition;
forming a layer of a powder bed by melting or sintering a portion of the particles of the powder with an energy beam;
heating the powder bed to a temperature below a melting temperature of the particles; and
repeating the forming of at least one additional layer of the powder bed by melting at least one additional portion of the particles of the powder to form the component.
2. The method of claim 1 , wherein the shell of the particles has a thickness of at least 0.1 μm and at most 3 μm.
3. The method of claim 1 , wherein the particles have a particle size of at least 10 μm and at most 100 μm.
4. The method of claim 1 , wherein the melting or sintering of the portion of the particles of the powder and the melting of the at least one additional portion of the particles of the powder comprises electron beam melting.
5. The method of claim 1 , wherein the first metallic alloy composition is a superalloy.
6. The method of claim 5 , wherein the heating of the powder bed comprises heating the powder bed to a temperature of at least 800° C. and at most 1200° C.
7. The method of claim 6 , further comprising:
cooling the temperature of the powder bed down at a rate of at most 1° C./s following formation of the component.
8. The method of claim 1 , wherein the particles have an average particle size in a range of 25 μm to 30 μm.
9. The method of claim 1 , wherein the shell of the particles comprises tungsten or chromium.
10. The method of claim 1 , wherein the shell comprises more than 99 mass % of an element that has a highest melting temperature of elements within the first metallic alloy composition and the second metallic alloy composition of the particle.
11. The method of claim 10 , wherein the element is tungsten.