U.S. patent application number 11/162221 was filed with the patent office on 2007-03-01 for nickel-base superalloy.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Ramgopal NMN Darolia, Kevin Swayne O'Hara, William Scott Walston.
Application Number | 20070044869 11/162221 |
Document ID | / |
Family ID | 37441123 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070044869 |
Kind Code |
A1 |
Darolia; Ramgopal NMN ; et
al. |
March 1, 2007 |
NICKEL-BASE SUPERALLOY
Abstract
A nickel-base alloy that exhibits a desirable balance of
mechanical properties, environmental properties, and
microstructural stability suitable for gas turbine engine
applications. The nickel-base alloy is in the form of a
single-crystal casting consisting of, by weight, 5.75% to 6.5%
aluminum, 4% to 5% tantalum, 2% to 6% chromium, 5.5% to 7%
tungsten, 1.5% to 3% molybdenum, 4% to 5% rhenium, up to 1.0%
niobium, 10% to 16% cobalt, up to 1% titanium, 0.01% to 0.05%
carbon, up to 0.005% boron, up to 0.01% yttrium, 0.5% to 1.0%
hafnium, the balance nickel and incidental impurities. The alloy
has a density of not more than 0.320 lbs/in.sup.3 (about 8.87
g/cm.sup.3), and contains a combined amount of aluminum, tungsten,
molybdenum, niobium, titanium, and hafnium specified relative to
the combined amount of tantalum and rhenium.
Inventors: |
Darolia; Ramgopal NMN; (West
Chester, OH) ; Walston; William Scott; (Cincinnati,
OH) ; O'Hara; Kevin Swayne; (Boxford, MA) |
Correspondence
Address: |
HARTMAN AND HARTMAN, P.C.
552 EAST 700 NORTH
VAIPARAISO
IN
46383
US
|
Assignee: |
GENERAL ELECTRIC COMPANY
1 River Road
Schenectady
NY
|
Family ID: |
37441123 |
Appl. No.: |
11/162221 |
Filed: |
September 1, 2005 |
Current U.S.
Class: |
148/410 ;
148/428; 420/444; 420/448 |
Current CPC
Class: |
C30B 29/52 20130101;
C22F 1/10 20130101; C22C 19/057 20130101 |
Class at
Publication: |
148/410 ;
148/428; 420/444; 420/448 |
International
Class: |
C22C 19/05 20060101
C22C019/05 |
Claims
1. A single-crystal casting formed of a nickel-base alloy
consisting of, by weight: 5.75% to 6.5% aluminum; about 4.0% up to
5.0% tantalum; 2.0% to 6.0% chromium; 5.5% to 7.0% tungsten; 1.5%
to 3.0% molybdenum; 4.0% to about 5.0% rhenium; up to 1.0% niobium;
10.0% to 16.0% cobalt; up to 1.0% titanium; 0.01% to 0.05% carbon;
up to 0.005% boron; up to 0.01% yttrium; 0.5% to 1.0% hafnium; the
balance nickel and incidental impurities; where in the density of
the alloy is not greater than 3.20 lb/in.sup.3 and the alloy has a
delta ratio of less than one calculated with the formula
(Al+W+Mo+Nb+Ti+Hf-13.15)/(12.6-Ta--Re) wherein Al, W, Mo, Nb, Ti,
Hf, Ta, and Re are the levels of aluminum, tungsten, molybdenum,
niobium, titanium, hafnium, tantalum, and rhenium, respectively, in
weight percent.
2. The single-crystal casting according to claim 1, wherein the
alloy consists of, by weight, 6.0 to 6.25% aluminum, 4.0 to 5.0%
tantalum, 2.0 to 6.0% chromium, 5.5 to 7.0% tungsten, 1.5 to 3.0%
molybdenum, 4.0 to 5.0% rhenium, 0.5 to 1.0% niobium, 10.0 to 12.0%
cobalt, 0.25 to 1.0% titanium, 0.01 to 0.05% carbon, 0.001 to
0.005% boron, 0 to 0.01% yttrium, 0.5 to 1.0% hafnium, the balance
nickel and incidental impurities.
3. The single-crystal casting according to claim 1, wherein the
alloy consists of, by weight, 6.0 to 6.25% aluminum, 4.0 to 5.0%
tantalum, about 4.2% chromium, 6.0 to 7.0% tungsten, about 1.5%
molybdenum, 4.0 to 5.0% rhenium, about 0.75% niobium, about 10.0%
cobalt, about 0.3% titanium, about 0.03% carbon, about 0.004%
boron, about 0.004% yttrium, about 0.6% hafnium, the balance nickel
and incidental impurities.
4. The single-crystal casting according to claim 1, wherein the
alloy contains of, by weight, about 4.0% tantalum, about 6.0%
tungsten, and about 5.0% rhenium.
5. The single-crystal casting according to claim 1, wherein the
alloy has a density of 0.315 to 0.319 lb/in.sup.3.
6. The single-crystal casting according to claim 1, wherein the
alloy has a delta ratio of less than 0.9.
7. The single-crystal casting according to claim 1, wherein the
casting is a gas turbine engine component.
8. A single-crystal casting formed of a nickel-base alloy
consisting of, by weight: 6.00% to 6.25% aluminum; about 4.0% up to
5.0% tantalum; 2.0% to 6.0% chromium; about 6.0% up to 7.0%
tungsten; 1.5% to 3.0% molybdenum; 4.0% to about 5.0% rhenium; 0.5%
to 1.0% niobium; 10.0% to 12.0% cobalt; 0.25% to 1.0% titanium;
0.01% to 0.05% carbon; 0.001% to 0.005% boron; up to 0.01% yttrium;
0.5% to 1.0% hafnium; the balance nickel and incidental impurities;
where in the density of the alloy is less than 3.20 lb/in.sup.3 and
the alloy has a delta ratio of less than one calculated with the
formula (Al+W+Mo+Nb+Ti+Hf-13.15)/(12.6-Ta--Re) wherein Al, W, Mo,
Nb, Ti, Hf, Ta, and Re are the levels of aluminum, tungsten,
molybdenum, niobium, titanium, hafnium, tantalum, and rhenium,
respectively, in weight percent.
9. The single-crystal casting according to claim 8, wherein the
molybdenum content in the alloy is greater than 2.0 weight
percent.
10. The single-crystal casting according to claim 8, wherein the
molybdenum content in the alloy is greater than 2.25 weight
percent.
11. The single-crystal casting according to claim 8, wherein the
alloy has a density of 0.315 to 0.318 lbs/in.sup.3.
12. The single-crystal casting according to claim 8, wherein the
alloy has a delta ratio of less than 0.9.
13. The single-crystal casting according to claim 8, wherein the
alloy contains of, by weight, about 4.0% tantalum, about 6.0%
tungsten, and about 5.0% rhenium.
14. The single-crystal casting according to claim 8, wherein the
casting is a gas turbine engine component.
15. The single-crystal casting according to claim 8, wherein the
alloy consists of, by weight, about 6.1% aluminum, about 4.0%
tantalum, 4.0 to 4.2% chromium, 5.5 to 6.5% tungsten, 1.50 to 3.0%
molybdenum, 4.5 to 5.0% rhenium, about 0.75% niobium, about 10.0%
cobalt, 0.3 to 0.5% titanium, about 0.03% carbon, about 0.004%
boron, about 0.004% yttrium, about 0.6% hafnium, the balance nickel
and incidental impurities.
16. The single-crystal casting according to claim 15, wherein the
molybdenum content in the alloy is greater than 2.0 weight
percent.
17. The single-crystal casting according to claim 15, wherein the
molybdenum content in the alloy is greater than 2.25 weight
percent.
18. The single-crystal casting according to claim 15, wherein the
alloy has a density of 0.315 to 0.318 lbs/in.sup.3.
19. The single-crystal casting according to claim 15, wherein the
alloy has a delta ratio of less than 0.9.
20. The single-crystal casting according to claim 15, wherein the
casting is a gas turbine engine component.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to nickel-base
alloys. More particularly, this invention relates to a nickel-base
superalloy capable of being cast as a single-crystal article and
exhibiting desirable properties for use in gas turbine engine
applications.
[0002] The superalloy commercially known as Rene N6, disclosed in
commonly-assigned U.S. Pat. No. 5,455,120, has a nominal
composition of, by weight, about 12.5% Co, 4.2% Cr, 7.2% Ta, 5.75%
Al, 5.8% W, 5.4% Re, 1.4% Mo, 0.2% Hf, 0.05% C, 0.004% B, 0.01% Y,
the balance nickel and incidental impurities. N6 is well known to
have a number of very desirable properties for gas turbine engine
applications, such as the high pressure turbine blades and vanes of
aircraft gas turbine engines.
[0003] As with the formulation of other superalloys, the
composition of N6 is characterized by controlled concentrations of
certain critical alloying elements to achieve a desired mix of
properties. For use in gas turbine engine applications, such
properties include high temperature creep strength, oxidation and
corrosion resistance, resistance to low and high cycle fatigue (LCF
and HCF), and single-crystal castability. While N6 performs well in
applications within gas turbine engines, improvements would be
desirable. Often of interest is the desire to reduce weight and
cost, the latter of which is due in part to alloying constituents
such as tantalum and rhenium. However, obtaining such reductions is
difficult in view of the desire to maintain or often improve other
properties of the alloy, including oxidation resistance and
microstructural stability. With regard to the latter issue,
microstructural instability is known to occur in various high
strength superalloys when protected with coatings containing
relatively high levels of aluminum, such as a diffusion aluminide
environmental coating or bond coat. In particular, aluminum
migration out of such coatings and into the underlying superalloy
substrate can result in the formation of topologically close-packed
(TCP) phases that, if present at sufficiently high levels, reduce
the load-carrying capability of the alloy. The incidence of TCP
phases has been associated with superalloys that contain
significant amounts of refractory elements such as rhenium,
tungsten, tantalum, hafnium, molybdenum, niobium, and
zirconium.
BRIEF SUMMARY OF THE INVENTION
[0004] The present invention provides a nickel-base alloy that
exhibits a desirable balance of high-temperature strength
(including creep resistance), oxidation and corrosion resistance,
resistance to low and high cycle fatigue, castability, and
microstructural stability so as to be suitable for components of
gas turbine engines, such as the high pressure turbine blades and
vanes of gas turbine engines. These properties are achieved with an
alloy that is lower in density than the superalloy known as Rene
N6, and in which relatively higher levels of aluminum, tungsten,
molybdenum, niobium (columbium), titanium, and hafnium are present
and relatively lower levels of tantalum and rhenium are present as
compared to N6.
[0005] According to the invention, the nickel-base alloy is in the
form of a single-crystal casting consisting of, by weight, 5.75% to
6.5% aluminum, 4% to 5% tantalum, 2% to 6% chromium, 5.5% to 7%
tungsten, 1.5% to 3% molybdenum, 4% to 5% rhenium, up to 1.0%
niobium, 10% to 16% cobalt, up to 1% titanium, 0.01% to 0.05%
carbon, up to 0.005% boron, up to 0.01% yttrium, 0.5% to 1.0%
hafnium, the balance nickel and incidental impurities. Importantly,
the density of the alloy is not more than and preferably less than
0.320 lbs/in.sup.3 (about 8.87 g/cm.sup.3). In preferred
embodiments, molybdenum is present in an amount greater than 1.5
weight percent, molybdenum is present in an amount greater than 1.5
weight percent, rhenium and tantalum are each present in an amount
less than 5 weight percent, and hafnium is present in an amount
greater than 0.5 weight percent.
[0006] As noted above, the nickel-base alloy of the present
invention nominally contains more aluminum, tungsten, molybdenum,
niobium, titanium, and hafnium and less tantalum and rhenium than
N6. For the purpose of characterizing the alloy, these groups of
alloys are designated as "delta addition" and "delta reduction"
elements, respectively. According to the present invention, the
ratio of delta addition to delta reduction elements (hereinafter,
delta ratio) is less than 1.0. The limitation that the value of the
delta ratio is less than unity reflects the determination of this
invention that, contrary to conventional wisdom, the combination of
(Al+Mo+W+Ti+Hf+Nb) is, by weight, a more potent strengthener than
(Re+Ta).
[0007] The alloy of this invention is believed to have properties
comparable to, and in some instances better than, those of the N6
alloy, particularly with the above-noted restriction on the delta
ratio, which allows for lower tantalum and rhenium contents.
Consequently, the alloy of this invention provides an excellent
lower density (weight) and potentially lower-cost alternative to
N6.
[0008] Other objects and advantages of this invention will be
better appreciated from the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 depicts a high pressure turbine blade that can be
formed from the nickel-base superalloy of the present
invention.
[0010] FIGS. 2 through 7 are graphs plotting yield strength,
tensile strength, 1800.degree. F. rupture, 2000.degree. F. rupture,
2100F rupture, and 1600.degree. F. high cycle fatigue life of
alloys prepared during investigations leading to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0011] The present invention was the result of an effort to develop
a nickel-base alloy having properties comparable to the nickel-base
alloy commercially known as Rene N6, but with a chemistry that
reduces the density and cost of the alloy while maintaining or
improving high temperature strength (including creep resistance),
oxidation resistance, fatigue resistance, castability, and
microstructural stability (resistance to TCP formation) for use in
such applications as the hot gas flow path of gas turbine engines.
As an example, FIG. 1 depicts a high pressure turbine (HPT) blade
10 having an airfoil 12, a dovetail 14 by which the blade 10 is
anchored to a turbine disk (not shown), and a platform 16
therebetween. While the advantages of this invention will be
described with reference to components of a gas turbine, such as
the high pressure turbine blade 10 shown in FIG. 1, the teachings
of this invention are generally applicable to other components that
require high temperature capabilities.
[0012] In a first round of investigations, alloys having the
approximate chemistries set forth in Table I below were formulated.
Specimens of various sizes were machined from single crystal slab
castings that had been solution heat treated at about 2370.degree.
F. (about 1300.degree. C.) for about six hours and then aged at
about 1975.degree. F. (about 1080.degree. C.) for about four hours.
The densities of the alloys were in the range of about 0.315 to
0.319 lbs/in.sup.3 (about 8.73 to about 8.84 g/cm.sup.3), which is
significantly less than the density of N6 (0.323 lbs/in.sup.3;
about 8.95 g/cm.sup.3). For reference, Table I also includes the
nominal composition for N6. TABLE-US-00001 TABLE I Al Ta Cr W Mo Re
Nb Co Ti C B Y Hf Ni N6 5.75 7.2 4.2 5.8 1.4 5.4 -- 12.5 -- 0.05
0.004 0.01 0.2 bal. 1 6.25 4.0 4.2 6.0 1.5 4.0 1.50 10.0 0.3 0.03
0.004 0.004 0.6 61.6 2 6.25 5.0 4.2 7.0 1.5 4.0 0.75 10.0 0.3 0.03
0.004 0.004 0.6 60.4 3 6.00 5.0 4.2 6.0 1.5 5.0 1.50 10.0 0.3 0.03
0.004 0.004 0.6 59.9 4 6.25 4.0 4.2 7.0 1.5 4.0 1.50 10.0 0.3 0.03
0.004 0.004 0.6 60.6 5 6.25 5.0 4.2 7.0 1.5 5.0 0.75 10.0 0.3 0.03
0.004 0.004 0.6 59.4 6 6.25 5.0 4.2 6.0 1.5 5.0 1.50 10.0 0.3 0.03
0.004 0.004 0.6 59.6 7 6.00 5.0 4.2 7.0 1.5 4.0 1.50 10.0 0.3 0.03
0.004 0.004 0.6 59.9 8 6.00 4.0 4.2 7.0 1.5 5.0 1.50 10.0 0.3 0.03
0.004 0.004 0.6 59.9 9 6.00 4.0 4.2 7.0 1.5 5.0 0.75 10.0 0.3 0.03
0.004 0.004 0.6 60.6 10 6.25 4.0 4.2 6.0 1.5 5.0 0.75 10.0 0.3 0.03
0.004 0.004 0.6 61.4 11 6.00 5.0 4.2 6.0 1.5 4.0 0.75 10.0 0.3 0.03
0.004 0.004 0.6 61.6 12 6.00 4.0 4.2 6.0 1.5 4.0 0.75 10.0 0.3 0.03
0.004 0.004 0.6 62.6 13 6.125 4.5 4.2 6.5 1.5 4.5 1.13 10.0 0.3
0.03 0.004 0.004 0.6 60.6 14 6.125 5.5 4.2 6.5 1.5 4.5 1.13 10.0
0.3 0.03 0.004 0.004 0.6 59.6
[0013] The above alloying levels were selected to evaluate the
affects of adding the relatively lighter elements titanium and
niobium, increasing the levels of tungsten, hafnium, and relatively
lighter elements such as aluminum and molybdenum, and reducing the
levels of heavier elements such as tantalum and rhenium in alloys
based on N6. The approach of the investigation was also to maintain
the total gamma-prime precipitation hardening phase while
evaluating the affects of altering the amounts of rhenium,
molybdenum, and tungsten that go into the gamma phase. As known in
the art, the high-temperature strength of a nickel-base superalloy
is directly related to the volume fraction of the gamma-prime
phase, which in turn is directly related to the total amount of the
gamma prime-forming elements (aluminum, titanium, tantalum,
niobium, and hafnium) present. Based on these relationships, the
composition and volume fraction of the gamma-prime phase and the
amounts of the gamma prime-forming elements required to maintain a
given strength level can be approximately estimated based on the
starting chemistry of the alloy and some basic assumptions about
the phases that form. It was initially viewed that an alloy having
the desired level of creep strength for a HPT blade should contain
at least as much gamma prime-forming elements (about 15.8 atomic
percent of aluminum, tantalum, niobium, titanium, and hafnium
combined) and as much gamma-forming elements (about 4.7 atomic
percent of rhenium, molybdenum, and tungsten combined) as nominally
contained in N6. However, other properties important to HPT blades
and other hot gas flow path components, such as fatigue life,
castability, metallurgical stability, and oxidation resistance,
cannot be predicted from amounts of these and other elements.
[0014] Tensile and yield strengths of the alloys are summarized in
FIGS. 2 and 3, in which "N6 avg" identifies historical averages for
N6. The data indicate that yield and tensile strengths of the
specimens were similar to and generally higher than, respectively,
N6.
[0015] FIGS. 4-6 are graphs plotting time to stress rupture for
Alloys 1-14 in comparison to historical averages for N6 ("N6 avg").
Samples from each alloy were machined to form conventional creep
test specimens and stress rupture tested in accordance with ASTM
E139 at stress and temperature combinations of about 40 ksi (about
276 MPa) and about 1800.degree. F. (about 980.degree. C.), about 20
ksi (about 138 MPa) and about 2000.degree. F. (about 1090.degree.
C.), and about 13 ksi (about 90 MPa) and about 2100.degree. F.
(about 1150.degree. C.). Specimens from all but one alloy exhibited
stress rupture strength approaching N6 at 1800.degree. F., and
Alloys 9, 10, and 11 exhibited the best overall stress rupture
performance at the three test temperatures.
[0016] FIG. 7 is a graph plotting axial-axial high cycle fatigue
(HCF) life at about 1600.degree. F. (about 870.degree. C.) for
Alloys 9, 10, and 11 in comparison to N6 baseline data. The HCF
tests were conducted under the stress-controlled condition and
about 60 Hz cyclic loading. The data indicate that the HCF lives of
Alloys 9, 10, and 11 were equal or better than the N6 baseline at
the temperature tested.
[0017] On the basis of Alloys 9, 10, 11, an alloy having the
approximate broad and nominal compositions (by weight) summarized
in Table II is believed to have properties similar to N6 and
therefore suitable for use as an alloy for hot gas path components
of gas turbine engines, as well as other applications in which
similar properties are required. The densities of Alloys 9, 10, and
11 were about 0.319 lbs/in.sup.3 (about 8.82 g/cm.sup.3), about
0.316 lbs/in.sup.3 (about 8.74 g/cm.sup.3), and about 0.317
lbs/in.sup.3 (about 8.77 g/cm.sup.3), respectively. It is believed
that an alloy within the ranges set forth in Table II can be
satisfactorily heat treated using the treatment described above.
TABLE-US-00002 TABLE II BROAD PREFERRED NOMINAL Al 5.75 to 6.5 6.00
to 6.5 6.125 Ta 4.0 to 5.0 4.0 to 5.0 4.5 Cr 2.0 to 6.0 2.0 to 6.0
4.2 W 5.5 to 7.0 5.5 to 7.0 6.5 Mo 1.5 to 3.0 1.5 to 3.0 1.5 Re 4.0
to 5.0 4.0 to 5.0 4.5 Nb 0 to 1.0 0.5 to 1.0 0.75 Co 10.0 to 16.0
10.0 to 12.0 10.0 Ti 0 to 1.0 0.25 to 1.0 0.3 C 0.01 to 0.05 0.01
to 0.05 0.03 B 0 to 0.005 0.001 to 0.005 0.004 Y 0 to 0.01 0 to
0.01 0.004 Hf 0.5 to 1.0 0.5 to 1.0 0.60 Ni balance balance
balance
[0018] It should be noted that the relative amounts of niobium,
tantalum, tungsten, and rhenium appeared to be particularly
important for both strength and microstructural stability
(resistance to TCP formation). Specifically, data obtained with the
alloys of Table I coated with diffusion aluminide coatings showed
that certain alloys of Table I appeared to exhibit lower incidence
of TCP phases if they contained, by weight, 0.75% (e.g., less than
1%) niobium, 6% (e.g., less than 7%) tungsten, and 4% (e.g., less
than 5%) tantalum. On this basis, it was theorized that strength
and microstructural stability could be further promoted by
adjusting the compositions set forth in Table 11 to contain, by
weight, about 4.0% tantalum, about 6.0% tungsten, and about 5.0%
rhenium.
[0019] Because of their excellent mechanical properties and low
densities, Alloys 9, 10, and 11 were further characterized on the
basis of, in comparison to the nominal composition of N6 (Table 1),
their nominal decreases in the levels of the relatively heavy
elements tantalum and rhenium and their nominal increases in the
levels of aluminum, tungsten, molybdenum, niobium, titanium, and
hafnium levels (of which all but tungsten and hafnium are
significantly less dense than tantalum and rhenium). The sums of
these increased and decreased levels, designated herein as delta
additions and delta reductions, respectively, are summarized for
Alloys 9, 10, and 11 in Table III, as is the ratio of delta
additions to delta reductions for each alloy (delta ratio).
TABLE-US-00003 TABLE III ALLOY 9 ALLOY 10 ALLOY 11 ALLOY 14
.DELTA.Al 0.25 0.50 0.25 0.375 .DELTA.W 1.2 0.2 0.2 0.7 .DELTA.Mo
0.1 0.1 0.1 0.1 .DELTA.Nb 0.75 0.75 0.75 1.13 .DELTA.Ti 0.3 0.3 0.3
0.3 .DELTA.Hf 0.4 0.4 0.4 0.4 Delta Addition 3.0 2.25 2.0 3.005
.DELTA.Ta 3.2 3.2 2.2 1.7 .DELTA.Re 0.4 0.4 1.4 0.9 Delta Reduction
3.6 3.6 3.6 2.6 Delta Ratio 0.83 0.62 0.55 1.15
[0020] From the above, it can be seen that the delta ratios of
Alloys 9, 10, and 11 were less than one. For comparison, the delta
ratio of Alloy 14 is also calculated in Table Ill. In view of these
results, it was concluded that the delta ratios of the alloys could
be used as indicators of their abilities to exhibit desirable
mechanical properties relative to their densities, with lower delta
ratios evidencing lower densities as compared to N6. Based on the
nominal composition of N6 as set forth in Table I, the calculation
of the delta ratio for alloys within the scope of this invention
can be made using the following formulas: Delta
Ratio=(Al-5.75+W-5.8+Mo-1.4+Nb+Ti+Hf-0.2)/(7.2-Ta+5.4-Re) or
(Al+W+Mo+Nb+Ti+Hf-13.15)/(12.6-Ta--Re)
[0021] A second round of alloys was then identified for further
testing based on the knowledge gained from the first round. The
alloying levels for the second round of alloys identified as Alloys
15-25 in Table IV below were selected to evaluate the affects of
limiting tantalum and niobium levels to the minimum present in
Alloys 9, 10, and 11, reducing the tungsten content, and increasing
the molybdenum content. In part, the approach taken with Alloys
15-25 is to approximately maintain levels of gamma prime-forming
elements similar to that nominally contained in N6 (about 15.8
atomic percent of aluminum, tantalum, niobium, titanium, and
hafnium combined) without increasing density. Alloys 15-25 also
reflect the intent to maintain a delta ratio of less than one.
TABLE-US-00004 TABLE IV Al Ta Cr W Mo Re Nb Co Ti Ru C B Y Hf N6
5.7 7.2 4.2 5.5 1.4 5.4 -- 12.5 -- -- 0.0 0.004 0.01 0.2 15 6.1 4.0
4.2 5.5 2.25 4.5 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 16 6.1 4.0
4.2 6.0 3.00 4.5 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 17 6.1 4.0
4.2 6.0 2.25 4.5 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 18 6.1 4.0
4.2 5.5 3.00 5.0 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 19 6.1 4.0
4.2 5.5 2.25 5.0 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 20 6.1 4.0
4.2 6.0 3.00 5.0 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 21 6.1 4.0
4.2 6.0 2.25 5.0 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 22 6.1 4.0
4.2 6.0 3.00 5.0 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6 23 6.1 4.0
4.2 6.0 1.50 5.0 0.4 10.0 0.5 0.0 0.0 0.004 0.004 0.6 24 6.1 4.0
4.2 6.0 1.50 5.0 0.7 10.0 0.5 0.0 0.0 0.004 0.004 0.6 25 6.1 4.0
4.0 6.5 2.25 5.0 0.7 10.0 0.3 0.0 0.0 0.004 0.004 0.6
[0022] Alloys 15-25 can generally be summarized as covering the
ranges and nominal compositions (by weight) summarized in Table V
below. TABLE-US-00005 TABLE V RANGE NOMINAL Al 6.00 to 6.25 6.1 Ta
4.0 to 5.0 4.0 Cr 2.0 to 6.0 4.2 W 6.0 to 7.0 6.0 Mo 1.5 to 3.0
2.25 Re 4.0 to 5.0 4.75 Nb 0.5 to 1.0 0.75 Co 10.0 to 12.0 10.0 Ti
0.25 to 1.0 0.3 C 0.01 to 0.05 0.03 B 0.001 to 0.005 0.004 Y 0 to
0.01 0.004 Hf 0.5 to 1.0 0.60 Ni balance balance
[0023] Preparation of Alloys 15-25 for testing is currently
underway.
[0024] While the invention has been described in terms of a
preferred embodiment, it is apparent that other forms could be
adopted by one skilled in the art. Therefore, the scope of the
invention is to be limited only by the following claims.
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