METHOD FOR PRODUCING A COMPONENT FROM A GRADED TiAl ALLOY AND COMPONENT PRODUCED THEREFROM

Abstract

A method for producing a component from a TiAl alloy and a correspondingly produced component includes defining at least one first component region with a first property profile, and at least one second component region with a second property profile, which is different from the first property profile; providing a powder made of the TiAl alloy; additively manufacturing the component from the powder composed of the TiAl alloy, wherein the powder made of the TiAl alloy is melted for the cohesive binding of the powder particles to one another and to the substrate or to an already produced part of the component, and wherein the powder particles are melted for the formation of the first component region, and the powder particles for the formation of the second component region are melted under different conditions, so different chemical compositions of the deposited material are produced in both component regions.

Claims

1. A method for producing a component from a TiAl alloy, comprising the following steps: defining at least one first component region having a first property profile, and at least one second component region having a second property profile, which is different from the first property profile; providing a powder composed of the TiAl alloy; additively manufacturing the component from the powder made of the TiAl alloy, wherein the powder made of the TiAl alloy is melted for the cohesive binding of the powder particles to one another and to the substrate or to an already produced part of the component, and wherein the powder particles are melted for the formation of the first component region and the powder particles for the formation of the second component region are melted under different conditions in such a way that different chemical compositions of the deposited material are produced in the first component region and in the second component region.

2. The method according to claim 1, wherein the different conditions for melting the powder include different melting temperatures and/or different holding times in the molten state, and/or different surrounding pressures.

3. The method according to claim 1, wherein the different conditions for melting the powder are selected so that different quantities of aluminum are vaporized.

4. The method according to claim 1, wherein the different conditions for melting the powder during the production of the first and/or the second component region are varied over the corresponding first and/or second component region to such an extent that a material gradient is deposited in the corresponding first and/or second component region.

5. The method according to claim 1, wherein the property profile in the first component region has a greater ductility than in the second component region, and/or in that the property profile in the second component region has a greater creep resistance than in the first component region.

6. The method according to claim 1, wherein during the melting of the powder, 0 to 1 at. % Al is vaporized in the first component region and/or 2 to 4 at. % Al are vaporized in the second component region.

7. The method according to claim 1, wherein a third or additional component regions are defined that have different property profiles than the first and/or second component regions.

8. The method according to claim 1, wherein the first and/or second component regions are formed so that they have transition regions at their boundaries, in which the property profiles and/or the chemical compositions, and/or the microstructure are adjusted stepwise or continuously to the surrounding regions.

9. The method according to claim 1, wherein the additive manufacture comprises selective laser beam melting, selective electron beam melting, and build-up welding.

10. The method according to claim 1, wherein the TiAl powder provided for the additive manufacture is composed of an alloy that contains 45.5 to 48 at. % Al, 4 to 6 at. % Nb, and in total up to 2 at. % of the alloying elements Mo, W, Zr, Si, C and B, and the remainder of Ti along with unavoidable contaminants, and in that, after the additive processing, the component produced has first component regions that contain a maximum 44.5 to 48 at. % Al, 4 to 6 at. % Nb, and in total up to 2 at. % of the alloying elements Mo, W, Zr, Si, C and B, and the remainder of Ti along with unavoidable contaminants, and second component regions that contain a minimum of 43.5 to 46 at. % Al, 4 to 6 at. % Nb, and in total up to 2 at. % of the alloying elements Mo, W, Zr, Si, C and B, and the remainder of Ti along with unavoidable contaminants.

11. The method according to claim 1, wherein after the additive manufacture, the component is subjected to a heat treatment, in particular a heat treatment that comprises at least two different annealing treatments, namely a solution annealing in the range of the solution temperature for -TiAl and an aging treatment at 800 to 950 C. for 2 to 6 hours with oven cooling.

12. The method according to claim 11, wherein the solution annealing is carried out by hot isostatic pressing of the component, and/or in that the solution annealing is carried out at a temperature of 50 to 20 C. below the solution temperature of the -TiAl of the first component region or the component region with the highest Al concentration.

13. The method of claim 1, wherein a component of a turbomachine made of a TiAl alloy is produced and is fabricated in one piece by additive manufacture, wherein the component comprises at least one first component region that has a first property profile, and at least one second component region that has a second property profile, which is different from the first property profile, wherein first and second component regions have different chemical compositions and different microstructures.

14. The method according to claim 13, wherein the component is a blade and the first component region is an edge region of the blade, and the second component region is a core region of the blade, wherein the first component region has a greater ductility than the second component region and the second component region has a greater creep resistance than the first component region.

15. The component according to claim 13, wherein the first component region has a structure containing greater than or equal to 30 vol. % globular -TiAl, and the second component region has a structure containing less than or equal to 1 vol. % globular -TiAl.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0025] The appended drawing shows, in a purely schematic way in the single appended FIGURE, a representation of a turbine blade that is manufactured corresponding to the method according to the invention.

DESCRIPTION OF THE INVENTION

[0026] Further advantages, characteristics and features of the present invention will become apparent in the following detailed description of the examples of embodiment. Of course, the invention is not limited to these exemplary embodiments.

[0027] The FIGURE shows a blade 1 of a turbomachine having a blade element 2 and a blade root 3 as well as an inner shroud 4 arranged between blade element 2 and blade root 3. The blade 1 is formed from a TiAl alloy that has, for example, a composition of 43.5 at. % aluminum, 4 at. % niobium, 1 at. % molybdenum, as well as 0.1 at. % boron, with the remainder of titanium along with unavoidable contaminants. The blade 1 is additively formed from a powder material of the TiAl alloy by selective laser beam melting or selective electron beam melting, in which, layer by layer, corresponding to the cross section of the blade 1, the blade 1 is formed by corresponding build-up of layers onto the part of the blade 1 that has already been manufactured by melting and solidifying powder composed of the TiAl alloy.

[0028] In the FIGURE, a plane 10 is shown, which, for example, intersects the blade root 3, so that a rectangular cross section 12 of the blade root 3 results. In the layer by layer build-up of the blade 1 along the build-up direction 11, which is indicated by the arrow, with layer by layer deposition of the TiAl powder in layers parallel to the plane 10, powder material is deposited by melting and solidifying in the corresponding layer that is here given by the cross section 12 of the blade root 3, thus, in the example shown of plane 10, a rectangular layer of the powder material on the already existing part of the blade root 3. Accordingly, in each case, a cross-sectional region of the blade 1, the region being produced along the build-up direction 11 through a cross section of the blade 1 with a plane parallel to the plane 10, is deposited by melting and subsequent solidifying of powder material.

[0029] As results from the appended FIGURE, the blade root 3 and the shroud 4 are built up homogeneously from the TiAl alloy of the powder material, while in the region of the blade element 2, the blade 1 has two different component regions, namely a first component region 5 in the form of a sheath or shell and a second component region 6 in the form of a core of the blade element 2.

[0030] The first component region 5 and the second component region 6 of the blade element 2 differ with respect to their chemical composition and structure. In the first component region 5, which forms the sheath or shell of the blade element 2, the blade 1 has a higher aluminum percentage than in the second component region 6, which forms the core of the blade element 2. Correspondingly, the structure of the first component region 5 is shown to have a higher percentage of globular -phase (-TiAl) than the second component region 6. By way of example, the percentage of globular -phase in the first component region 5 is greater than or equal to 30 vol %, while the percentage of globular -TiAl in the second component region 6 can be smaller than or equal to 1 vol %. Due to the high percentage of globular -TiAl in the first component region 5, the first component region 5 in the shape of the sheath or shell has a higher ductility than the second component region 6. In contrast, however, the second component region 6 in the form of the core of the blade element 2 possesses a higher creep resistance based on the low percentage of globular -TiAl, so that with high operating temperatures and centrifugal forces, which act on rotating blades of turbomachines, the creep deformation of the blade element 2 can be prevented or at least limited.

[0031] The different chemical compositions with different aluminum contents in the first component region 5 and in the second component region 6 as well as the different microstructures resulting therefrom with different percentages of globular -TiAl can be achieved in the additive manufacture by selective laser melting or selective electron beam melting, due to the fact that the powder material composed of the TiAl alloy is melted and re-solidified under different conditions. Thus, in the second component region 6, which forms the core of the blade element 2, the deposition of the powder material composed of the TiAl alloy can be produced by vaporizing more aluminum during the deposition, thus during the melting and re-solidifying, so that the aluminum percentage is reduced in the second component region 6. This can be achieved, for example, by increasing the melting temperature, and/or reducing the pressure of the surrounding atmosphere, for example, of a protective gas atmosphere.

[0032] Correspondingly, the blade 1 has a smaller aluminum percentage in the second component region 6 after the additive manufacture. In a subsequent heat treatment, for example, by hot isostatic pressing at a high temperature near the solvus temperature of the -TiAl, for the first component region with high aluminum percentage, thus the solution temperature of the -TiAl, at which -TiAl dissolves, but below the melting point or solidus temperature, there occurs a dissolution of the -TiAl in the second component region [[5]]6 with low aluminum percentage, in which the solvus temperature is lower, so that in the second component region 6, after cooling from the solution annealing temperature or the temperature for the hot isostatic pressing in the second component region 6, the percentage of globular -TiAl is small. Instead of this, lamellar -TiAl is formed, which has a high creep resistance, but a lesser ductility.

[0033] After the solution annealing treatment or the hot isostatic pressing, another temperature treatment can be conducted, in which the blade 1 is subjected to an aging annealing, for example, in the range of 850 to 950 C. for 2 to 6 hours in order to bring the blade 1 into thermodynamic equilibrium in the range of the operating temperatures of the blade. After this, another concluding final processing of the blade 1 can be produced.

[0034] Although the present invention has been described in detail on the basis of the exemplary embodiments, it is obvious to the person skilled in the art that the invention is not limited to these exemplary embodiments, but rather that modifications are possible in such a way that individual features are omitted or other types of combinations of features can be realized, without leaving the scope of protection of the appended claims. In particular, the present disclosure encompasses all combinations of the individual features shown in the different examples of embodiment, so that individual features that are described only in conjunction with one exemplary embodiment can also be used in other exemplary embodiments or combinations of individual features that are not explicitly shown can also be employed.