METHOD OF MAKING A MOLYBDENUM ALLOY HAVING A HIGH TITANIUM CONTENT

Abstract

The invention relates to method of making a molybdenum alloy which has a high titanium content and further comprises silicon and/or boron. The method comprises subjecting to pressureless sintering or sintering under pressure in an inert gas atmosphere a mixture of one or more powders (i) of an alloy of Mo and Ti and, optionally, one or more additional metals X and/or (i) powders of Mo and of TiN, and (ii) one or more powders comprising one or more powders of silicides of Mo and/or Ti and/or (iii) one or more powders of nitrides which comprise Si.sub.3N.sub.4 powder and/or BN powder.

Claims

1. A method of making a molybdenum alloy having a high titanium content and further comprising one or both of silicon and boron, wherein the method comprises subjecting to pressureless sintering or sintering under pressure a mixture of powders which comprise (i) one or more powders of an alloy of Mo and Ti and, optionally, one or more additional metals X and/or (i) powders of Mo and of titanium nitride, and at least one of (ii) one or more powders comprising one or more powders of silicides of Mo and/or Ti and (iii) one or more powders of nitrides which comprise at least one of silicon nitride and boron nitride.

2. The method of claim 1, wherein X is present and selected from one or more of Fe, Y, Hf, Nb, Zr, W.

3. The method of claim 2, wherein the one or more metals X comprises at least Fe.

4. The method of claim 1, wherein one or more powders (i) are employed.

5. The method of claim 4, wherein the one or more powders (i) have a median particle size d50 of from about 0.001 m to about 50 m.

6. The method of claim 1, wherein the particles of (i) are substantially spherical.

7. The method of claim 1, wherein one or more powders (ii) are employed.

8. The method of claim 7, wherein the one or more powders (ii) comprise powders of one or more of MoTi.sub.5Si.sub.3, Ti.sub.5Si.sub.3, MoTi.sub.5SiB.sub.2, Mo.sub.3Si.

9. The method of claim 1, wherein one or more powders (iii) are employed.

10. The method of claim 9, wherein the one or more powders (iii) comprise at least silicon nitride powder.

11. The method of claim 1, wherein one or more powders (i) are employed.

12. The method of claim 11, wherein the one or more powders (i) have a median particle size d50 of from about 0.001 m to about 50 m.

13. The method of claim 1, wherein the powders (i) and/or (i) and the powders (ii) and/or (iii) are combined in ratios which result in an alloy which comprises at least 35 at. % of molybdenum.

14. The method of claim 13, wherein the powders (i) and/or (i) and the powders (ii) and/or (iii) are combined in ratios which result in an alloy which comprises not more than 66 at. % of molybdenum.

15. The method of claim 1, wherein the powders (i) and/or (i) and the powders (ii) and/or (iii) are combined in ratios which result in an alloy which comprises at least 25 at. % of titanium.

16. The method of claim 15, wherein the powders (i) and/or (i) and the powders (ii) and/or (iii) are combined in ratios which result in an alloy which comprises not more than 33 at. % of titanium.

17. The method of claim 1, wherein the powders (i) and/or (i) and the powders (ii) and/or (iii) are combined in ratios which result in an alloy which comprises at least 9 at. % of silicon.

18. The method of claim 17, wherein the powders (i) and/or (i) and the powders (ii) and/or (iii) are combined in ratios which result in an alloy which comprises not more than 15 at. % of silicon.

19. An alloy which is obtained by the method of claim 1.

20. An article which is made of or comprises the alloy of claim 19.

Description

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0015] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

[0016] As set forth above, the method provided by the present invention comprises subjecting to pressureless sintering or sintering under pressure a mixture of powders which comprise (i) one or more powders of an alloy of Mo and Ti and, optionally, one or more additional metals X (e.g., one or more of Fe, Y, Hf, Nb, Zr, W and preferably at least Fe) and/or (i) powders of Mo and of TiN, and further comprise (ii) one or more powders comprising one or more powders of silicides (and preferably also borides) of Mo and/or Ti and/or (iii) one or more powders of nitrides which comprise Si.sub.3N.sub.4 powder and/or BN powder. Especially in cases where powders (iii) are employed in combination with powders (ii), powders (iii) may not comprise Si.sub.3N.sub.4 powder.

[0017] The powders (i) may either be purchased (e.g. from H. C. Starck, Germany) or may be prepared, for example, by atomization in an inert gas atmosphere (preferably high purity argon) of a block or ingot of an alloy of Mo, Ti and, optionally, X to obtain a powder with particles which will usually be substantially spherical and will have a particle size (longest dimension and/or diameter) of less than 45 m (e.g., less than 10 m, or less than 1 m). The alloy can be prepared, for example, by melting together (e.g., by plasma melting or arc melting) powders of metallic Mo, Ti and optionally one or more metals X and/or corresponding pre-alloys such as, e.g., Mo.sub.80Ti.sub.20, Mo.sub.70Ti.sub.30, Mo.sub.60Ti.sub.40, etc. (e.g., in powder form). Powders (i) may be prepared, for example, by reducing molybdenum oxides with e.g., hydrogen and by nitriding Ti powder, respectively. In this regard it is to be noted that the phrase less than z m as used herein is intended to mean that at least 95% by weight, e.g., at least 98% by weight, or at least 99% by weight of the particles have a longest dimension or diameter of z m. The particle size can be determined by methods well known to those of skill in the art, for example by sieve analysis or optical methods such as laser diffraction.

[0018] The atomization of an ingot or block may, for example, be carried out by an EIGA (Electrode Induction melting Gas Atomization) process or by gas atomization using a Laval nozzle (preferably using high purity argon). The atomization may optionally be preceded by subjecting the alloy obtained by, e.g., arc melting or plasma melting to hot isostatic pressing (HIP), e.g., at a temperature of from about 1,300 C. to about 1,500 C. and at a pressure of from about 100 to about 300 MPa for about 5 to about 10 hours. Prior to and/or after the hot isostatic pressing a heat treatment may be carried out, e.g., at a temperature of from about 1,300 C. to about 1,600 C. for about 5 to about 50 hours.

[0019] Non-limiting examples of commercially available powders (i) for use in the instant method have a median particle size d50 in the range from about 0.01 m to about 50 m (at a purity of, e.g., from about 95% to about 99.9% by weight) or a d50 of from about 0.01 m to about 30 m (at a purity of, e.g., from about 98% to about 99.9% by weight).

[0020] The alloy of Mo, Ti and, optionally, X for making the one or more powders (i) may, for example, comprise (in % by weight based on the total weight of the alloy):

[0021] Mo from about 55 to about 95, e.g. from about 60 to about 85

[0022] Ti from about 10 to about 30, e.g. from about 15 to about 25

[0023] Fe from 0 to about 3, e.g. from about 1 to about 2

[0024] Nb from 0 to about 30, e.g. from about 10 to about 20

[0025] Zr from 0 to about 10, e.g. from about 2 to about 4

[0026] W from 0 to about 20, e.g. from about 4 to about 10

[0027] Hf from 0 to about 3, e.g. from about 1 to about 2

[0028] Y from 0 to about 3, e.g. from about 1 to about 2.

[0029] If present, one, two, three, four, five or all of Fe, Nb, Zr, W, Hf and Y may be present in the alloy.

[0030] The alloy for making the one or more powders (i) preferably does not contain any (or at most only trace amounts) of Si and B because the presence of these elements will cause the alloy to become brittle. The same applies to the one or more powders (i).

[0031] Non-limiting examples of commercially available Mo powders (i) for use in the instant method have a median particle size d50 in the range from about 0.1 m to about 50 m (at a purity of, e.g., from about 95% to about 99.9% by weight) or a d50 of from about 0.5 m to about 2 m (at a purity of, e.g., from about 98% to about 99.9% by weight). The same applies to TiN powders.

[0032] The one or more powders (ii) for use in the instant method may comprise powders of one or more of Mo(Ti).sub.5Si.sub.3, Ti.sub.5Si.sub.3, Mo(Ti).sub.5SiB.sub.2, Mo.sub.3Si. The one or more powders (ii) may either be purchased (e.g., from H. C. Starck, Germany) or may be prepared by, for example, arc melting (usually in an argon atmosphere) from elemental Mo, Ti and Si (and preferably B), usually in the form of powders of the elements and/or corresponding pre-alloys. The powders (ii) will usually comprise one or more phases of formula MoTi.sub.5Si.sub.3, Ti.sub.5Si.sub.3, MoTi, and MoTi.sub.5SiB.sub.2 and/or corresponding substoichiometric or hyperstoichometric phases. For example, these phases may contain more or less Si and/or B than indicated, or may contain Mo and/or Ti, which can activate the sintering process and can result in high sinter densities (e.g., >95%).

[0033] The powders (ii) for use in the instant method will usually have a median particle size d50 (as determined by, e.g., laser diffraction) in the range from about 0.001 m to about 50 m, e.g., from about 0.001 m to about 40 m, or from about 0.001 to about 30 m.

[0034] Non-limiting examples of commercially available powders (ii) for use in the instant method may have a median particle size d50 as follows: [0035] Mo.sub.3Si from about 10 m to about 30 m (at a purity of, e.g., from about 98% to about 99.99% by weight) or from about 1 m to about 10 m (at a purity of, e.g., from about 99% to about 99.9% by weight) [0036] Ti.sub.5Si.sub.3 from about 10 m to about 30 m (at a purity of, e.g., from about 98% to about 99.9% by weight) [0037] Mo(Ti).sub.5Si.sub.3 from about 0.01 m to about 50 m (at a purity of, e.g., from about 98% to about 99.99% by weight) or from about 0.01 m to about 30 m (at a purity of, e.g., from about 99% to about 99.9% by weight) [0038] Mo(Ti).sub.5SiB.sub.2 from about 0.01 m to about 50 m (at a purity of, e.g., from about 98% to about 99.99% by weight) or from about 0.01 m to about 30 m (at a purity of, e.g., from about 99% to about 99.9% by weight).

[0039] The one or more powders (iii) which may be used in combination with or instead of the one or more powders (ii) are readily commercially available (e.g., from H. C. Starck, Germany).

[0040] The powders (iii) for use in the instant method will usually have a median particle size d50 (as determined by, e.g., laser diffraction) in the range from about 0.001 m to about 50 m, e.g., from about 0.001 m to about 40 m, or from about 0.001 to about 30 m.

[0041] Non-limiting examples of commercially available powders (iii) for use in the instant method may have a median particle size d50 as follows: [0042] Si.sub.3N.sub.4 from about 0.1 m to about 5 m (at a purity of, e.g., from about 95% to about 99.9% by weight) or from about 0.5 m to about 1 m (at a purity of, e.g., from about 98% to about 99.9% by weight) [0043] BN from about 0.1 m to about 5 m (at a purity of, e.g., from about 95% to about 99.9% by weight) or from about 0.5 m to about 1 m (at a purity of, e.g., from about 98% to about 99.9% by weight).

[0044] The powders (i) and/or (i) and the powders (ii) and/or (iii) are mixed and optionally milled, and then subjected to a sintering process (either pressureless or under pressure in a reducing or inert gas atmosphere, e.g., an atmosphere consisting essentially of Ar/H.sub.2 or helium). Corresponding processes are well known to those of skill in the art. Prior to sintering the mixed (and optionally milled) powders will usually be combined with a preferably organic binder (e.g., an organic wax) and then subjected to cold isostatic pressing (CIP) at room temperature, e.g., at a pressure of from about 100 to about 300 MPa for, e.g., about 5 to about 60 minutes, to form a green body.

[0045] The one or more powders (i) or (i) are usually mixed with the one or more powders (ii) and/or (iii) in ratios which result in a weight percentage of the one or more powders (i) and/or the one or more powders (i) of at least about 85%, e.g., at least about 88%, at least about 90%, at least about 92%, or at least about 94% by weight, but usually not higher than about 97%, e.g., not higher than about 96% by weight, based on the total weight of the powder mixture (i.e., without optional binder). Merely by way of example, weight percentages of powders (i) and (iii) in a corresponding mixture may be as follows:

[0046] Powder (i) from about 85 to about 97, e.g., from about 92 to about 96

[0047] Si.sub.3N.sub.4 from about 2 to about 15, e.g., from about 3 to about 7

[0048] BN from about 0.5 to about 5, e.g., from about 1 to about 3.

[0049] The sintering (or reaction sintering if nitrides are present) is usually carried out in several (e.g., two, three or four) steps at different temperatures. Merely by way of example, the sintering may be carried out, in each case with a holding time of from about 1 to about 3 hours, (1) at a temperature of from about 350 C. to about 450 C. (e.g., at about 400 C.) to decompose the optionally present organic binder, (2) at a temperature of from about 650 C. to about 750 C. (e.g., at about 700 C.) to decompose nitrides, if present, (3) at a temperature of from about 1,150 C. to about 1,250 C. (e.g., at about 1,200 C.) and (4) at a temperature of from about 1,650 C. to about 1,750 C. (e.g., at about 1,700 C.).

[0050] The sintered body thus obtained may optionally be subjected to hot isostatic pressing (HIP), e.g., at a temperature of from about 1,300 C. to about 1,500 C. and at a pressure of from about 100 to about 300 MPa for about 5 to about 10 hours. Prior to and/or after the HIP a heat treatment may be carried out, e.g., at a temperature of from about 1,300 C. to about 1,600 C. for about 5 to about 50 hours.

[0051] The sintered body may also be subjected to forming (optionally preceded by HIP and/or heat treatment(s) as set forth above) such as, e.g., rolling, extrusion, forging (e.g., isothermal or hot die), optionally followed by a heat treatment as set forth above.

[0052] It should also be noted that in the case of the absence of nitrides in the powder mixture the sintering (and the CIP) can be replaced by a generative production method, e.g. by using a laser with which a desired structure is built up layer by layer, the laser being used to sinter each deposited layer of powder material before the next layer of powder material is deposited.

[0053] The following embodiments of the instant method are provided for purely illustrative purposes.

Embodiment 1

[0054] A powder (i) was prepared by arc melting of a powder mixture of elemental Mo (81% by weight), Ti (18% by weight) and Fe (1% by weight) to form an ingot, followed by atomization of the ingot by means of a Laval nozzle. The powder (i) (93% by weight based on powder mixture) was then mixed with powders (iii) of Si.sub.3N.sub.4 (5% by weight) and BN (2% by weight) in a planetary ball mill (mass ratio balls:powder=10:1, 100 rev/min) for 15 minutes and the resultant mixture was combined with an organic binder (e.g., wax) and then subjected to CIP for about 10 minutes at about 300 MPa and thereafter to reaction sintering at about 400 C. for about 1 hour in an Ar/H.sub.2 atmosphere, about 700 C. for about 1 hour in an Ar/H.sub.2 atmosphere, about 1,200 C. for about 1 hour in vacuum and about 1,700 C. for about 1 hour in vacuum, followed by a heat treatment at about 1,400 C. for about 10 hours and HIP for about 5 hours at about 1,400 C. and about 150 MPa. The resultant product showed the following (approximate) concentrations (in at. %):

[0055] Mo 57

[0056] Ti 25

[0057] Fe 1

[0058] Si 9

[0059] B 8

Embodiment 2

[0060] A powder (i) is prepared by plasma melting of a powder mixture of elemental Mo, Ti, Fe and Hf to form an ingot, followed by atomization of the ingot by means of a Laval nozzle. The powder (i) is then mixed with powders (iii) of Si.sub.3N.sub.4 and BN and an organic binder and the resultant mixture is subjected to CIP and thereafter to reaction sintering at temperatures of about 400 C., about 700 C., about 1,200 C. and about 1,700 C., each for about 1-3 hours in a reducing atmosphere or in vacuum, followed by a heat treatment at about 1,400 C. for about 10 hours and HIP for about 5 hours at about 1,400 C. and about 150 MPa.

Embodiment 3

[0061] A powder (i) is prepared by are melting or plasma melting of a powder mixture of elemental Mo, Ti, Fe, Y, Hf, Nb, Zr and W to form an ingot, followed by an optional heat treatment, optional HIP and atomization of the ingot by means of a Laval nozzle or by means of an EIGA method. The powder (i) is then mixed with powders (iii) of Si.sub.3N.sub.4 and BN and an organic binder and the resultant mixture is subjected to CIP and thereafter to reaction sintering at temperatures of about 400 C., about 700 C., about 1,200 C. and about 1,700 C., each for about 1-3 hours in a reducing atmosphere or in vacuum, followed by optional HIP for about 5 to about 10 hours at a temperature of from about 1,300 C. to about 1,500 C. and a pressure of from about 100 to about 300 MPa, forming by rolling, extrusion or forging at a temperature of higher than 1,600 C. and a subsequent heat treatment for about 5 to about 50 hours at a temperature of from about 1,300 C. to about 1,600 C.

Embodiment 4

[0062] A powder (i) is prepared by plasma melting of a powder mixture of elemental Mo, Ti and Fe to form an ingot, followed by atomization of the ingot by means of a Laval nozzle. The powder (i) is then mixed with powders (ii) of Mo(Ti).sub.5Si.sub.3 and Mo(Ti).sub.5SiB.sub.2 and an organic binder and the resultant mixture is subjected to CIP and thereafter to sintering at temperatures of about 400 C., about 1,200 C. and about 1,700 C., each for about 1-3 hours in a reducing atmosphere or in vacuum, followed by a heat treatment at about 1,400 C. for about 10 hours and HIP for about 5 hours at about 1,400 C. and about 150 MPa.

Embodiment 5

[0063] A powder mixture (i) of elemental Mo and of TiN is mixed with powders (iii) of Si.sub.3N.sub.4 and BN and an organic binder and the resultant mixture is subjected to CIP and thereafter to reaction sintering at temperatures of about 400 C., about 700 C., about 1,200 C. and about 1,700 C., each for about 1-3 hours in a reducing atmosphere or in vacuum, followed by a heat treatment at about 1,400 C. for about 10 hours and HIP for about 5 hours at about 1,400 C. and about 150 MPa.

[0064] As set forth above, the method of the present invention is suitable for making molybdenum alloys which have a high titanium content. The term molybdenum alloy as used herein and in the appended claims refers to an alloy in which the element molybdenum makes up the greatest alloying fraction in at. %. In other words, in a molybdenum alloy, there is no other element which has a greater alloying fraction in at. % than Mo. The molybdenum content of the alloy in at. % will usually be at least 30 at. %, preferably at least 35 at. %, and in particular at least 40 at. %, e.g., at least 45 at. % (based on all elements present in the alloy, as in the following).

[0065] High titanium content as used herein and in the appended claims refers to a titanium content of at least 15 at. %, preferably at least 20 at. % and particularly at least 25 at. %, e.g., at least 30 at. %.

[0066] In one aspect, the alloy made by the instant method may further comprise iron and/or yttrium, each in a concentration of from 0.1 to 5 at. %, in particular in a concentration of from 0.3 to 3 at. %. For example, iron may be present in a concentration of from 0.5 to 3 at. %, e.g., from 0.8 to 2 at. %, and/or yttrium may be present in a concentration of from 0.3 to 3 at. %, e.g., from 0.5 to 2 at. %.

[0067] The alloy produced by the method of the present invention may further comprise one or more of zirconium, niobium, hafnium, and tungsten. For example, zirconium may be present in a concentration of not more than 5 at. %, e.g., in a concentration of from 0.3 to 3 at. %, and/or niobium may be present in a concentration of not more than 20 at. %, e.g., in a concentration of from 0.3 to 10 at. %, and/or tungsten may be present in a concentration of not more than 8 at. %, e.g., in a concentration of from 0.3 to 5 at. % and/or hafnium may be present in a concentration of not more than 5 at. %, e.g., in a concentration of from 0.3 to 3 at. %.

[0068] The alloy of the present invention may comprise silicon in a concentration of from 9 to 15 at. %, e.g., in a concentration of from 12 to 14 at. %, and/or boron in a concentration of from 5 to 9 at. %, e.g., in a concentration of from 5 to 6 at. %, and/or titanium in a concentration of from 25 to 33 at. %, e.g., in a concentration of from 26 to 29 at. %.

[0069] The alloy may, for example, be formed exclusively of molybdenum, silicon, boron, titanium, iron, yttrium, niobium, tungsten, zirconium, hafnium (and unavoidable impurities), or may be formed exclusively of molybdenum, silicon, boron, titanium, iron, yttrium (or hafnium).

[0070] In another aspect of the alloy, molybdenum may be present in a concentration of from 35 to 66 at. %, e.g., in a concentration of from 40 to 60 at. %, or from 45 to 57 at. %, or in a concentration such that the alloy comprises 100 at. % together with the remaining alloying constituents mentioned.

[0071] In another aspect, the true density of the produced alloy may be less than or equal to 9 g/cm.sup.3, e.g., less than or equal to 8.5 g/cm.sup.3, or less than or equal to 8 g/cm.sup.3.

[0072] In yet another aspect, the structure of the alloy may comprise a matrix of a molybdenum mixed crystal and silicide phases, the silicide phases being formed in particular by Mo(Ti).sub.5Si.sub.3 and/or Mo(Ti).sub.5SiB.sub.2. For example, the alloy may comprise from about 15 to about 35 vol. %, e.g., from about 25 to about 35 vol. % Mo(Ti).sub.5Si.sub.3 and from about 15 to about 35 vol. %, e.g., from about 15 to about 25 vol. % Mo(Ti).sub.5SiB.sub.2 and from about 1 to about 20 vol. % minor phases. Also by way of example, the alloy may comprise from about 45 to about 55 vol. %, e.g., from about 48 to about 55 vol. %, molybdenum mixed crystal or a fraction of molybdenum mixed crystal such that the alloy together with the remaining phase constituents comprises 100 vol. %.

[0073] As minor alloying constituents, one or both of niobium and tungsten may additionally be present in the alloy. The addition of niobium improves the fracture toughness and therefore the deformability or ductility, whereas tungsten improves the oxidation resistance of the alloy.

[0074] Preferably, the alloy is formed exclusively of the elements molybdenum, silicon, boron, titanium, iron, yttrium, niobium, tungsten, hafnium and zirconium, wherein the fraction of niobium, tungsten, hafnium and zirconium may be 0 at. %. As is known to those skilled in the art, an alloy can comprise further elements as unavoidable impurities, wherein, however, none of these further elements should make up more than 1 at. %, preferably more than 0.1 at. %, in the alloy.

[0075] With the main and minor alloying elements, therefore, alloys can be produced by the method of the present invention which, in addition to unavoidable impurities, exclusively comprise Mo, Si, B, Ti, Fe, Y, Zr, Nb, Hf and/or W. In particular, MoSiBTiFe, MoSiBTiFeZr, MoSiBTiFeY, MoSiBTiFeYNb and MoSiBTiFeYNbW alloys can be produced, likewise a MoSiBTiY alloy which does not comprise iron, although an alloy containing iron is preferred in principle.

[0076] The alloy composition can in particular also be selected in such a manner that the true density, that is to say the density without any pores or cavities, is adjusted to be less than or equal to 9 g/cm.sup.3, e.g., less than or equal to 8.5 g/cm.sup.3, or less than or equal to 8 g/cm.sup.3.

[0077] The corresponding structure of the alloy can be adjusted in such a manner that the structure has a matrix of molybdenum mixed crystal (e.g., molybdenum-titanium mixed crystal), into which the silicide phases are incorporated, wherein the silicide phases can be formed by Mo(Ti).sub.5Si.sub.3 and/or Mo(Ti).sub.5SiB.sub.2. In the respective silicides, therefore, molybdenum can be replaced by titanium and vice versa.

[0078] The molybdenum alloy made by the method of the present invention may comprise from 15 to 35 vol. %, e.g., from 25 to 35 vol. % Mo(Ti).sub.5Si.sub.3 and from 15 to 35 vol. %, e.g., from 15 to 25 vol. % Mo(Ti).sub.5SiB.sub.2 and from 1 to 20 vol. %, e.g., from 1 to 5 vol. %, minor phases. Minor phases can comprise various phases, in particular various mixed phases or mixed crystals of the alloying elements present in the alloy.

[0079] The molybdenum alloy may additionally comprise from about 45 to about 55 vol. %, e.g., from about 48 to about 55 vol. %, molybdenum mixed crystal or a fraction of molybdenum mixed crystal such that the alloy together with the remaining phase constituents comprises 100 vol. %.

[0080] With a corresponding molybdenum alloy, in particular components of turbomachines, preferably of gas turbines or aero engines can be manufactured, wherein the components can be, in particular, rotor blades or guide vanes of the turbomachine, and in particular guide vanes or rotor vanes of rapidly running uncooled low-pressure turbines.

[0081] Advantageous properties having a balanced property profile with respect to creep resistance, static strength, fracture toughness, ductility, oxidation resistance and low specific gravity have been achieved with the following exemplary alloy compositions (figures in each case in at. %), which can also comprise small amounts of further elements as unavoidable impurities:

TABLE-US-00001 Mo Si B Ti Fe Y Zr Nb W Hf 49.5 12.5 8.5 27.5 2.0 0 0 0 0 0 48.5 13.5 8.5 26.5 2.0 0 1.0 0 0 0 51.0 10.0 8.5 27.5 2.0 0 1.0 0 0 0 46.5 12.5 8.5 27.5 2.0 2.0 1.0 0 0 0 46.5 12.5 8.5 27.5 2.0 2.0 0 1.0 0 0 46.5 12.5 8.5 27.5 2.0 2.0 0 0 1.0 0 49.3 13.5 5.5 27.5 1.2 0 0 0 1.0 0 50.5 13.5 5.5 27.5 2.0 0 0 0 0 1.0 53.0 13.5 5.5 27.0 1.0 0 0 0 0 0 51.0 13.5 5.5 27.0 1.0 0 0 0 0 2.0 46.0 13.5 5.5 27.0 1.0 0 0 5.0 0 2.0

[0082] Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.