DE1921359A1 - Casting alloys - Google Patents

Description

The present invention "relates to cast alloys, in particular on alloys based on nickel for casting ("investment cast") »the particularly for hot-stage gas turbine metal parts ("hot-stage gas turbine hardware "), is suitable.

A number of nickel-based alloys of sufficient strength for use at temperatures in the range of 926 ^° C. to 1067 ° C. are already known. These alloys

-X *

have been proposed for hot stage gas turbines and have been adapted for this application. In the past few years, nickel-based alloys including chromium, cobalt, molybdenum, tungsten, niobium, tantalum, aluminum, titanium, carbon, zirconium and box have been at the center of alloy development in this field. In general, the morphology of such alloys comprises a matrix with certain phases dispersed in the bulk of each crystal and at the crystal boundaries. The recently developed alloys on the

* for use in 909846/07 2 A

Based on nickel for use at extremely high temperatures, the basic phase of the crystalline basic structure consists of eutectic Gamraa basic phase, which probably consists essentially of Ni. * Al, with nickel partly through cobalt, chromium, iron etc. and aluminum partly through titanium, Niobium and other elements can be replaced. Mainly among the intra-granular and grain boundary phases there are various forms of carbide phases, generally defined by the formulas MC, M ₂₅ Cg and MgC. As a general rule it can be said that the carbide phase contributes to the reinforcement of the alloy without being significantly involved in a loss of ductility "*) if the carbon phases form relatively small particles and are generally distributed throughout the basic structure of the alloy crystals It is a general rule that if the carbide phases are preferentially deposited in the areas of grain boundaries, the carbides tend to be adversely affected, such as loss of ductility, to a considerable extent. This feature is not limited to "carbide phases". In general it can be said that at high temperatures the grain boundaries are the weak parts of any given alloy and phases which are preferentially deposited in regions of the grain boundaries contribute to a loss of ductility.

In general, as the strength of the alloys increases (usually by increasing the Additional elements), the ductility decreases. The metallurgists have learned a compromise between strength and Accept ductility. The alloys specified and specifically described below are commercially available represent acceptable tradeoffs between strength and ductility. However, the alloys described here represent *; Ductility = ductility, deformability etc.

909846 / 072A

does not represent simple compromises in the sense that for indicates a given strength at a given temperature, with a relatively smooth change Ductility must be expected. It has long been known that most Mckel-based alloys Strength properties to a sufficient extent exhibit that the alloys at temperatures of about

ο but

926 C and higher can be used that they / - as it is usually expressed - a ductility trough at a slightly lower temperature, usually around 760 ⁰ C, have. When the tensile elongation is plotted against the temperature, the usual curve shows little change between room temperature and about 705 ^° C. Between 705 ^° C. and about 843 ^° C. the ductility curve shows a minimum, and this minimum usually has a fourth, the one below that measured at room temperature! percentage elongation. One of the compromises the metallurgists have been forced to make has been an alloy that will achieve commercially acceptable elongation even at the lowest point of the ductility trough.

In relatively recent times, a very surprising phenomenon has been found with a certain high-temperature alloy, in particular with regard to the ductility at 76O ⁰ C. Conventionally, this particular alloy has been selected and developed on the basis of test results obtained using normal cast-to-size tensile and creep specimens. Each of the tests with the normal, technically customary test procedures, these samples, cast to size, showed all signs of a commercially available

* η

moderately acceptable ductility in the range of etv / a 760 C. However, if turbine metal parts such as turbine blades in a conventional, commercially acceptable manner one The castings obtained show that they are subjected to molding

* i.e. technically 90 9846/0724

often a ductility, "at about 760 ^° C., which is worse than desired. This phenomenon occurs" especially "in castings which are made from re-melted batches, ie batches that are more than about 5 $ an" previously melted and cast Alloy containing, have been produced. Further investigation of the separated metal parts samples showed that a mass effect occurs that is detrimental to the ductility in the critical area at about 76o C ^0. It was found that samples which were separated from the actual part cast to size very often gave much lower values for the percentage elongation and the percentage cross-sectional reduction in the tensile and creep ^{tests at 760 °} C. than those values which were more similar in tests Size of cast strain and creep samples were obtained. From a practical point of view, it is the job of a metallurgist to make a metal part that has good technical properties. The fact that the properties measured on normal size cast samples are not representative of the properties of the actual metal parts is an unpleasant and difficult problem, to which is added the problem caused by the presence of the known ductility trough about 76O ⁰ C is caused.

It has now been found that by slightly varying the chemical compositions of alloys which have a Commercially acceptable combination of plague and Ductility properties show the manufacture of Alloys that have a different tnikrοstructural Having morphology and increased ductility enables v / ird. At the same time, the alloys keep in the essentially the same or an improved combination of strength and other technical properties that for their applicability in the field of gas turbine

909846/0724

metal parts contribute to high temperatures.

It is an object of the present invention to provide new Nozzle metal parts for high temperatures and driving to create them.

Another object of the present invention is Creation of new alloys with improved ductility properties. - "

The accompanying drawings serve to explain the Invention, namely shows:

1 shows a graph of the tensile strength, Yield strength and elongation percentage of two alloys, 'plotted against temperature are, one within the scope of the invention and the other outside;

Figure 2 is a reproduction of a photomicrograph of a Alloy outside the invention;

Pig.2A a reproduction of a photomicrograph of an alloy according to the invention (comparable to the alloy shown in Pig, 2) \

pig. 3 a reproduction of a Mirkophotographic from another alloy outside the invention; . '

Pig, 3A is a representation of a photomicrograph of a alloy according to the invention (comparable to the alloy shown in Pig. 3); and

Pig. Figure 4 is a graph * of the creep properties of metal parts, in and out of range of the invention, with both alloys studied being made from remelted batches and

9Q9846 / 0724

1921353

the test specimens from die cast. Turbine blades have been obtained,

The present invention generally includes HoQh ~ Tempe.Ea, tur; « Parts of the door, such as Turbines look fine »-wings» One-piece cast turbine wheels and nozzle guide vanes.! Made from an alloy that is in its original Form commercially acceptable strength and Has ductility properties, this alloy by adding from about 0.1% by weight to about 4% by weight Hafnium has been modified to form the composition of the alloy. According to the invention, the hafnium can be used as a Substitute for an equal amount in percent by weight of nickel, tantalum and sometimes other refractory elements can be used in the alloy. Preferably will Hafnium in amounts from about $ 0.3 to about 1.2 # for that the same amount in percent by weight of tantalum is used if tantalum is used in the base alloy, which is improved according to the invention is present. In general it can be said that it is possible that the strength properties of the Base alloy cannot be changed considerably? if Hafnium is used for elements such as ζ, Β, tantalum in an alloy, but is used at the same time The ductility of the alloy is significantly increased. If hafnium instead of alloy additives such as nickel? is used, the ductility of the alloy becomes significant improved, while at the same time it is possible "that the strength properties of the base alloy are improved will. It should be noted, however, that the addition of hafnium to a nickel-based alloy 'd ^ e' already is largely provided with hardening elements and especially for the highest strength values at the highest Temperatures is determined without paying attention to the ductility, not necessarily to an increase in the Ductility to a generally commercially acceptable one

909846/0724

Value at temperatures that "trough" leads. In other "words, the subject matter of the present invention is not a substitute for acting on reasonable metallurgical considerations" in balancing alloy compositions to obtain a commercially acceptable tradeoff between strength and ductility. In the fresh batches ("virgin heats") it is advantageous to add at least more than about 0.5 # hafnium, for example at least about 0.7 $> hafnium, in order to achieve a considerable improvement in the mechanical properties of the cast alloys.

In many alloys adapted to the treatment of the present invention in accordance with the present invention, the ductility deficiencies appear to be much more apparent in remelted batches. When test samples obtained from turbine blades made from batches containing remelted fractions are examined under creep conditions of "760 ° C, such tests may indicate that there is virtually no ductility when the alloy contains no hafnium. On the other hand, the Applicant has found that the batch containing remelted fractions ensures metal parts the quality of which is at least fully equivalent to the quality of the metal parts recovered from fresh batches when the batch is modified to be from about 0.15 to about £ 0.15 in accordance with the present invention 1 % hafnium. The decisive reasons have not yet been fully clarified which lead according to the invention to the improvement of the properties of metal parts produced from remelted batches. However, it is assumed that when using the _o remelted batches unintentionally determined te * ° types of undesirable ^ impurities get into the metal in very small, ** - analytically undetectable amounts. Hafnium obviously has the ability to work with either. To connect impurities and to remove them effectively or the metallurgical balance of the alloys

BATH ORIGINAL

modify in such a way that the alloy is less be made sensitive to the impurities. . Regardless of the mechanism by which this causes this '.' the present invention is based in part on '. that the treatment of remelted batches / feed small amounts of hafnium the properties of such batches essentially the properties of fresh batches which equates to essentially the same alloys, if not further improved.

The chemical composition in percent by weight of some ' Known nickel-based alloys which can be modified according to the invention are shown in Table I below specified.

Table I.

A. B. 10 C. D. 12th ■ 2 ■ 8th E. C. 0.15 O, 0 0.15 O, 5 1 0.18 Cr 9.0 8th, 0 9.0 12, 012 10.0 Co 10.0 10, 10.0 - 10 15.0 W. 10.0 - 0 12.5 - 0 - Ko . 2.5 6, 25th 4, • 3.0 Ta 1.5 4, 0 - - - Ti 1.5 1, 0 2.0 O, 4.7 Al 5.5 6, 015 5.0 6, 5.5 B. 0.015 O, 10 0.015 O, 0.014 Zr 0.05 O, 0.05 O, 0.06 Cb - ~ - 1.0. 2, - V - - - - 1.0 Ni *) *) *) *) compensation

909846/0724

It should be noted that the compositions given in Table I. nominal compositions are and the percentages of each of the elements present by about - $ 10 of the specified amounts · can be varied. The alloys can also contain up to a total of about 2% by weight of random elements such as manganese, silicon, iron, etc. Non-metals such as sulfur, oxygen and nitrogen and harmful metals such as lead, bismuth, arsenic etc. are kept as low as possible in accordance with technical practice. Preferably all alloys mentioned in Table I and the alloys according to the invention are made by vacuum melting and poured into the casting mold, which has a gas turbine metal mold, while still under vacuum.

One skilled in the art can see from Table I that those Alloys according to the invention can advantageously be treated with the incorporation of hafnium in order to be technically advanced Create hot stage gas turbine metal parts, which correspond to the composition range in weight $ given in Table II.

Tabel to 13 Ji II Ti O ₁ * G $ 0.02 to $ 0.20 to 35 % Al 4th Size 7 to 1 to 14 % B. O ₁ o; o2 Go until to 8 Ji Zr O ₁ 0.15 W. until $ 6 Nb Mon until V , 5 to 6 5 <4 Ta until up to _v 7 # , 002 to .01 to up to 3 up to 1.

JUIU

Ni - balance (no less than about $ 36) / essential.

The addition of hafnium or, preferably, the replacement of hafnium in amounts -from about 0.15 to about 1.5% by weight or even 4% by weight in balanced alloy compositions

909846/0724

- ίο -

within the range given in Table II increases the ductility of the alloy, particularly in the area of the "trough", at about 76O ⁰ C, without adverse effects on other, important technical properties of the alloy. The addition of hafnium to the alloy occurs without difficulty after deoxidation and the modified alloy is then treated in the same way as if no modification had taken place. Alloys within the range given in Table II can, particularly with respect to the elements tantalum and tungsten (if tungsten is present at all), by maintaining the tungsten content above about 8% by weight and the total content of tantalum plus tungsten below about 13 or even 10 wt. % to be compensated.

The present invention particularly relates to new ones Alloy compositions as given in Table III below (in percent by weight).

Table III Alloy 1 Alloy 2

C 0.10 - Oi 18 jt, 0.03 - 0.13 #

Gr 7 - 11 # 7 - 10 '? S

Oo 6 - 13 $> 6 - 13 f »

W 8 - 12 Ji up to 2 "#

Mon 2-3 # 4-8 $

Ta up to 3 # 2.5 - 4.5 #

Ti 1 - 2 Jfi 0.5 - 1, '5 fo

Al 5 - 6 ^ 5.5 - 6.5 %

B. 0.004 - 0.02 i> 0.004 - 0.02 fi

Zr 0.02 - 0.2 $> 0.02 - 0.2 ^ .-

Hf 0.15-4 % 0.15-4 1>

Ni essentially equalization

909846/0724

Alloys 1 and 2 listed in Table III were melted and cast into size under vacuum Sample bars, metal parts and random samples poured for chemical analysis. Made of alloys A and B of Table I, comparative samples were prepared which, with the exception of hafnium, essentially comprised alloys 1 and 2, respectively were similar. In the following tables, Examples 1-1, 1-2, etc. represent various samples of alloy and Examples 2-1, 2-2, etc. represent various samples of Alloy 2. (See Table X).

The data in Table IV shows the properties of Alloy 2 versus Alloy B in test specimens cast to size in standard room temperature tensile strength tests. To adapt to the technical practice, all of the experiments described in Tables IV to VIII were carried out with vakuumgeschinolzenen and -gegossenen samples which were subjected to heat treatment for 4 hours at 108O ⁰ O with the following 10 hours prolonged heating to 900 ⁰ C.

Table IV,

Example for room temperature room temperature expansion no. ( Nominal) door UTS * door YS * # (kg / mm ² ) (k ^ / mm ² )

Legie
tion 3 O 94.0 70.7 8.0 2-1 0.5 91.3 76.0 8.5 2-2 t 93.2 79.5 6.0 2-3 1.5 110.0 79.8 14.0

* - U.T.S. = ultimate tensile strength in kg / mm

* - YS = yield point (0.2 % Greilze) in kg / mm ²

Table V shows the creep properties of alloys B.

909846/0724

and 2 the "were obtained in the investigation of standard samples cast to size at 76O ⁰ C and a load of 66.1 kg / mm.,"

Table V

Example $> Hf time to 'previous creep no. (nominal) fraction (hours) (#) * ■

alloy

B O 48 ^ ", 9

2-1 0.5 58.3 2.9

2-2 1 86.0 4.27

2-3 1.5 130.6 6.39

* - The previous creep indicates this by the strain gauge within 2 hours creep measured at failure.

The data in Tables 17 and V show that the mechanical properties of alloys B and 2 are at least equal, with the exception that at 76O ⁰ C the hafnium-containing alloys show a much greater ductility under conditions which cause creep, v / whether the break time is significantly increased.

Fig. 1 is a graph showing the tensile properties of alloys B and 2 (Examples 2-6) at temperatures ranging from room temperature to about 982 ⁰ C. The curves 11, 13 and 14 show the case Äuß ^ irst tensile strength, the yield strength or the percent elongation of the alloy of Example 2-6. Curves 12 and 15 show the ultimate tensile strength and the percent elongation, respectively, of alloy B. Pig 1 shows the improvement in ductility due to the incorporation of 1.5 % hafnium into the Alloy 2-6 can be seen from the improvement

909846/0724

- the percentage elongation is evident. The additional tensile strength values "at 760 ^° C. for" both Examples 2-1 and 2-3 show 9 # elongation, which proves excellent ductility at the "trough" temperature.

Pig. 2, 2A and 3 and 3A are reproductions of photomicrographs of alloys within and outside the inventive range. * Each of these pictures shows the alloy in about 50Ofacher magnification, the liquid after the polishing with a Ä'tz that one γόη by the addition of 20 ml of hydrogen fluoride and nitric acid to make 60 ml of glycerine was etched. Figure 2 shows Alloy B and Pig. 2A shows an alloy according to the invention which essentially consisted of the composition of alloy B plus 1.5 fo hafnium instead of the same weight percentage of nickel ". It can be seen that the writing-like carbide phases, as can be seen in Pig. does not appear in Pig. 2A. Furthermore, there appears to be much more primary gamma ground phase in Pig. 2A than in Pig.2 The same situation is with respect to the primary gamma ground phase "when comparing Pig. 3 and 3A can be seen. These figures represent microstructures of alloy A and an alloy according to the invention (example 1-3), which is identical to alloy A with the exception,

Λ r \ CJ

that 3 ₅ 3 / £ hafnium instead of / all of the tantalum and part of the nickel (total 3.3 wt. $) of the alloy is present.

The ductility properties of the remelted portion-containing batches of alloy B and similar alloys of the invention containing hafnium are given in Tables 71 and VII and in the drawing Pig. 4 illustrates. The values of Tables VI and VII, düe in P.ig. 4 were obtained from test samples obtained from turbine blades. As already stated, such test examples are now used in order to determine the ductility of the manufactured

909846/0724

ORIGINAL INSPECTED

th metal parts. Table VI gives tensile strength values at room temperature. Table VII contains the creep values obtained at 76O ⁰ O and one

Load of 59.8 kg / mm were obtained, and yy. 4th shows the creep curves for Alloy B and Example 2-1.

Table VI

Example $ Hf Zimraertem- room temperature- expansion

No. (nominal) temperature ₀ temperature X. S. %

ÜTS (ks / nmr ) (kg / mm ^z ) '

Alloy B O 81.6 76.3 3.5

2-1 '0.5 83.6 75.7 6.0

2-2,186.3 76.3. 6.0

2-3 1.5 91.9 76.7 9.5

Table VI shows that the inclusion of hafnium in the composition of Alloy B significantly increased ductility improves what can be seen from the samples, that of blades made from remelted: containing fractions Batches produced were obtained.

Table VII

Example #

H (nominal)

Time until Previous Break ( hours) Crawl $> 13.4 0.42 177.2 , 3.98 131.8 2.18 136.9 2.91

Alloy B O

2-1 0.5

2-2 1

2-3 1.5

The values in Table VII, particularly alloy B.

909846/0724

Values in question show a loss in ductility when using remelted batches containing fractions and samples obtained from cast iron. The creep curve for alloy B is shown in Pig. 4 of the drawing as curve 17. The extraordinarily strong improvement, the by incorporating 0.5 # hafnium in the composition of the remelted batches of Alloy B is illustrated by curve 16 in Figure 4. Creep curve 16 is the curve of Example 2-1, in this particular Pail a greater than 100% improvement in rupture time and at least an eight-fold increase in previous percent creep was obtained by adding 0.5 wt. % hafnium to the composition of alloy B. Experience has generally shown that the remelted fractions of the present invention batches of the hafnium-containing alloys containing batches of essentially the same alloy tion, but without hafnium, is largely equivalent.

The values in Table VIII show the results when part of the tantalum was replaced by hafnium in Alloy B. The fourth was obtained with test ingots cast to size.

Table VIII

Example # Hf RTUTSS RTYS * ₂ Deh- time advance no. (nominal) (kg / mm) (kg / mm) change?

keep crawling

O 5 94.0 77.1 8.0 76p ° C - 2nd 2 - O, 93.3 76.3 8.0 (Hours) 3 , 56 Alloy B. 1 5 96.7 77.8 11.0 - 3 , 67 e-4 1, 107.8 78.5 14.5 , 65.3 , 64 2-5 90.5 2-6 101.2

* RTUTS = Ziramer temperature value of the ultimate tensile strength

• RTY3 = Ziramer temperature value of the yield point

90 9846 / Cf? 2 4

ORIGINAL INSPECTED

Similar values were obtained with * cast to size test bars, by 50stündige heat treatment at 84-3 ⁰ C, · - are shown in Table IX for alloy A and the like, fiction, * · invention alloys. In the alloys of the invention, hafnium was used instead of all of the tantalum. * J and a part of the nickel up to a total weight percentage of nickel plus tantalum which corresponds to the weight percentage of the hafnium. .. · ■ ".

Table IX

========= Zeitstandr- time status-

Example? S Hf RTUTS _o RTYS _o Elongation No. (norn.) ( ^{Kg / mm 2} ) (kg / mm ² ) *

(Stdn) ($ elongation) mm 2 (Stdn)

tion A. 0 100.8 90.1 4.3 48 3.75 35

1-1 1.5 111.0 95.9 5.0 113.9 9 25.9

1-2 2.2 124.1 x 100.5 7.0 69.9 9.5 18.4

1-3 3.3 114.5 101.8 4.0 123.1 9 11.9

Table IX shows the applicability of the present invention to alloy A and demonstrates, in particular, that the desired improvement in ductility can be achieved using less than about 2 % by weight of hafnium, although relatively large amounts of hafnium can be used.

The analyzes of some of the alloys used that are used for Determination of the test results given here are used are listed in Table X. /

909846/0724

Table X

IzI * 1-2 (Weight brittle) 2-1 2-2 ■ 2-3 0.13 2-4 2-5 2-6 5.48 5.70 1-3 5.83 6.03 6.03 1.40 6.13 6.06 6.15 Al 0.017 0.017 5.60 0.015 0.018 0.017 0.018 0.015 0.01 B. 0.12 0.14 0.017 0.09. 0.10 0.10 0.05 0.07 0.07 σ 8.78 8.60 0.14 7.78 7.82 7.73 8.05 7.95 7.98 Or 10.1 10.0 8.55 9.88 9.80 9.78 9.79 9.79 9.72 Co- 2.52 2.47 9.85 6.00 5.77 5.75 6.05 6.10 6.12 Mon A "* A. 2.43 A. A. A. A. A. A. Ni 1.50 1.54 A. 1.08 1.06 1.05 1.03 1.08 1.08 Ti 9.90 9.80 1.59 <0.1 < ; 0.1 - <0.1. - - • 0.12 0.11 9.55 · 0.09 0.07 0.13 0.15 0.16 Zr. 1.50 2, -20 0.14 0.49 1, 10 0.53 1.03 1.55 Hf 3.30

Ta - - - 4.40 4.27 4.32 3.88 3.25 2.73

In the method according to the invention for the production of alloys containing hafnium and in particular in the treatment of the batches containing the remelted portions. Hafnium is added essentially as an element or in the form of a compound which decomposes to metallic hafnium under the alloying conditions. Thus, hafnium can be added as metallic hafnium, hafnium-rich metal or possibly as intermetallic hafnium compounds. The hafnium should be added to the molten alloy after the melt has been cleaned, for example by a "carbon-boil" stage, and practically calmed, in order to avoid the formation of excessive amounts of the very stable hafnium oxide. As those skilled in the art know, it is very advantageous / to carry out the melting and casting of alloys of the type described here under high vacuum in order to incorporate harmful amounts of oxygen, nitrogen, etc. /. to avoid in the alloy. Under certain conditions, however, the alloys described herein can be melted under inert gas or some other protection and in air * A = balance 9098 4 6/0724

be poured if the necessary caution is used. . . - .... = ■ ■■ '' -

9Ό98Λ6 / 07

Claims (1)

Claims 1. Alloy that is suitable for casting in the desired shape and 1 "is essentially not eohoiedable, thus identifiable «Eiohnet that egg · fliokel, Ohroa, aluminum, titanium» up to 6 Gtw · * Tantalum and «ine Gaama basic phase, as cast was, and eusätelioh contains about 0.1 to 4 wt. * Hafnium. 2. Alloy according to claim 1, characterized in that . «Ie hafnium in an amount of about 0.15 to about 1.5 wt. * Contains. 3. Alloy according to claims 1-2, characterized in that that the alloy is a fresh charge and hafnium in an amount of at least about 0.5 wt. *, preferably at least about 0.7 wt. *, contains * 4 * Alloy according to claims 1-3, characterized in that that they also contain carbon and one or more of the element (s) from the group consisting of tungsten, molybdenum, niobium, Contains vanadium, zircon and boron. 5. Alloy according to claims 1-4, characterized in that that they are about 0.02 to about 0.2 wt. * carbon, about 7 to about 13 wt. * Chromium, up to about 35 wt. * Cobalt, up to about 14 wt. * tungsten, up to about 8 wt. * molybdenum, about 0.5 to about 6 wt. * titanium, about 4 to about 7 wt. * aluminum, about 0.002 to about 0.02 wt. * boron, about 0.01 to about 0.15 wt. * zirconium, up to about Contains 3% by weight of niobium and up to about 1.5% by weight of vanadium, with the balance consisting essentially of nickel. .Alloy according to claims 1-5, characterized in that that the total amount of tantalum and tungsten does not exceed 13%. 909846/07 24 BAD ORlGtNAt "* Τ92Τ3 7. Alloy according to claim 6, characterized in that the amount of tungsten is at least about 8%. 8. Alloy according to claims 1-7, characterized in that the amount of cobalt Ms is about 13 % . 9. Alloy according to claims 1-8, characterized in that it contains about 0.10 to 0.18 wt. $ Carbon _f about 7 to 11 wt. $ Chromium, about 6 to 13 wt. $ Cobalt, about 8 to 12 wt . $ tungsten, about 2 to 3 $ by weight tantalum. $ molybdenum, about 3 wt.!, about 1 to 2 wt. $ titanium, about 5 to 6 wt. fo aluminum, about 0.004 to 0.02 wt.% boron, contains about 0.02 to 0.2 wt. % zirconium and about 0.5 to 4 wt.% hafnium, the balance consisting essentially of nickel. 10. Alloy according to claims 1-8, characterized in that it is about 0.03 to 0.13 wt. $ Carbon, about 7 to 10 wt. $ Chromium, about 6 Ms 13 wt. ^ Cobalt, up to to about 2 wt. $ tungsten, about 4 to 8 wt. $ molybdenum, about 2.5 to 4.5 wt. # tantalum, about 0.5 to 1.5 wt. # Titanium, about 5.5 to 6.5 wt. $ Aluminum, about 0.004 to 0.02 wt. # Boron, about 0.02 to 0.20 wt. $, Zirconium and contains about 0.50 to 4 wt. $ hafnium, the balance consisting essentially of nickel. 11. An alloy according to claims 1 -. 10, characterized in that as casting alloy than about 5 wt% of one already before the molten and cast alloy more. 12. Gas turbine metal parts produced by casting, characterized in that they are made of alloys Claims 1-10 have been cast. 9 09846/07 2 k 13. A method for reducing the harmful effect of a non-malleable of remelted units containing batches, nickel, chromium, aluminum, titanium, and a gamma-base phase-containing alloy, characterized in that by incorporation of about 0.3 Ms about 4 wt. Fo Hafnium prior to casting in the alloy, the deleterious effect of the remelted fractions containing and so "treated batch," is avoided. 14. The method according to claim 13, characterized in that an alloy is used which "up to β wt. $ Contains tantalum. 15. The method according to claims 13-14 »characterized in that during the incorporation of the hafnium, the alloy is kept under high vacuum. 16. The method according to claims 13-15 »characterized in that that the Gasturbinenmet'all share through. Casting the alloy under vacuum in the molten state in investment molds, which have substantially the shape of the metal parts, are formed. 17. A method for producing gas turbine metal parts which are suitable for use under load at temperatures up to about 1038 ⁰ C and have improved ductility at temperatures of about 704 to about 871 ⁰ C, characterized in that the casting with an alloy according to claims 1-10 under vacuum in the molten state in investment casting molds, which essentially have the same shape as the metal parts. The patent attorney 909846/0724 _wcn ORIGINAL INSPECTED