alloy

Abstract

The alloy contains, in atomic percent, not more than 19.45% aluminum, not more than 16.7% zirconium, not more than 12% vanadium, not more than 35.0% tungsten, not more than 15.0% chromium, not more than 6.5% iron, not more than 15.0% nickel, not more than 40.0% titanium, not more than 35.0% tantalum, not more than 35.0% niobium, not more than 35.0% molybdenum, not more than 20.0% cobalt, not more than 35.0% manganese, not more than 15.0% copper, not more than 10.0% hafnium, not more than 35.0% rhenium, not more than 15.0% platinum, not more than 15.0% palladium, not more than 20.0% rhodium, not more than 25.0% ruthenium, not more than 20.0% iridium, and not more than 5.0% silicon, with a total of not more than 1 atomic % incidental impurities, and satisfying the following formula: i is the atomic fraction of element i in the alloy, and VEC i is the number of valence electrons associated with an atom of element i, and R is the universal gas constant.

Description

[Technical Field]

[0001] The present invention relates to composite concentrated alloys (CCAs) designed for high temperature applications. These alloys offer a unique combination of high ductility, high temperature mechanical strength, and high manufacturability. In one embodiment, this can be achieved in combination with low density and / or reasonable alloy cost. [Background technology]

[0002] Conventional alloys with high mechanical strength at high temperatures typically rely on a major base element. Alloys with very high melting points are often based on refractory elements such as molybdenum, tungsten, niobium, and tantalum. While these alloys have very high melting points and high strength, their mechanical properties tend to decrease significantly as temperatures approach the alloy's melting point.

[0003] To address this challenge, recent development activities have been conducted in the areas of composite concentrated alloys (CCA) and refractory composite concentrated alloys (RCCA). However, currently proposed alloys have not achieved the desired combination of high melting points, high-temperature strength, high ductility, ease of fabrication, low density, and reasonable cost for commercial applications in fields such as gas turbine technology, jet turbine technology, and rocket propulsion. Examples of alloys that have been investigated to date are listed in Table 1. (Miracle et al., 2011; Senkov, Woodward, and Miracle, 2014; Gorr et al., 2017; Muller et al., 2019; Ge et al., 2020; Sheikh et al., 2020)

[0004] [Table 1]

[0005] CN109252082 discloses MoNb1.5Hf0.5Zr0.5Ti1.5 as a high-temperature structural alloy. The entropy of this alloy is only 12.512, which means that the alloy is susceptible to the formation of intermetallic phases. Indeed, one embodiment discloses a refractory high-entropy alloy in the multi-component alloy system (MoNb1.5Hf0.5Zr0.5Ti1.5)-(W0.4Al0.2Cr0.2C0.2). In this alloy, refractory metal carbides form within the alloy. The amount of carbon in the alloy is 3.3 atomic %.

[0006] The alloy of the present invention contains, in atomic percent, not more than 19.45% aluminum, not more than 16.7% zirconium, not more than 12% vanadium, not more than 35.0% tungsten, not more than 15.0% chromium, not more than 6.5% iron, not more than 15.0% nickel, not more than 40.0% titanium, not more than 35.0% tantalum, not more than 35.0% niobium, not more than 35.0% molybdenum, not more than 20.0% cobalt, not more than 35.0% manganese, not more than 15.0% copper, not more than 10.0% hafnium, not more than 35.0% rhenium, not more than 15.0% platinum, not more than 15.0% palladium, not more than 20.0% rhodium, not more than 25.0% ruthenium, not more than 20.0% iridium, and not more than 5.0% silicon, with incidental impurities totaling not more than 1 atomic %;

number

[0007] In one embodiment, the following equation is satisfied:

number

[0008] In one embodiment, the following equation is satisfied:

number

[0009] In one embodiment, the following equation is satisfied:

number

[0010] In one embodiment, the alloy contains up to 35% rhenium and A Re ≦(35- A Ta )+(35-A W )+(20-A Nb ), where A Re , A Ta , A W and A Nb are the atomic percentages of rhenium, tantalum, tungsten, and niobium, respectively. Such alloys are low in cost and density.

[0011] In one embodiment, the alloy contains up to 19.0 atomic percent aluminum, preferably up to 15.0 atomic percent aluminum, more preferably up to 10.0 atomic percent aluminum, even more preferably up to 5.0 atomic percent aluminum, and most preferably up to 1.0 atomic percent aluminum, which provides improved manufacturability.

[0012] In one embodiment, the alloy comprises up to 16.0 atomic percent zirconium, preferably up to 15.0 atomic percent zirconium, most preferably up to 14.0 atomic percent zirconium, preferably up to 13.0 atomic percent zirconium, more preferably up to 12.4 atomic percent zirconium, and most preferably up to 5.0 atomic percent zirconium, which reduces the risk of intermetallic compound formation and improves ductility.

[0013] In one embodiment, the alloy contains up to 10.0 atomic percent vanadium, preferably up to 7.3 atomic percent vanadium, more preferably up to 4.3 atomic percent vanadium, and most preferably up to 1.0 atomic percent vanadium, which reduces the risk of intermetallic compound formation and improves ductility.

[0014] In one embodiment, the alloy contains up to 10.0 atomic percent palladium, preferably up to 5.0 atomic percent palladium, more preferably up to 1.5 atomic percent palladium, even more preferably up to 1.0 atomic percent palladium, and most preferably up to 0.5 atomic percent palladium, which provides a low VEC and improved ductility.

[0015] In one embodiment, the alloy comprises up to 15.0 atomic percent Iridium, preferably up to 9.0 atomic percent Iridium, preferably up to 8.0 atomic percent Iridium, more preferably up to 1.0 atomic percent Iridium, preferably up to 0.5 atomic percent Iridium, more preferably up to 0.1 atomic percent Iridium, such alloys exhibit low VEC and improved ductility.

[0016] In one embodiment, the alloy contains up to 15.0 atomic percent rhodium, preferably up to 8.0 atomic percent rhodium, more preferably up to 6.0 atomic percent rhodium, more preferably up to 1.0 atomic percent rhodium, even more preferably up to 0.5 atomic percent rhodium, and most preferably up to 0.1 atomic percent rhodium, which provides a low VEC and improved ductility.

[0017] In one embodiment, the alloy comprises at least 2.0 atomic percent iridium, preferably at least 5.0 atomic percent iridium, more preferably at least 12.0 atomic percent iridium, and even more preferably at least 17.0 atomic percent iridium, which provides a higher melting point and improved resistance to environmental attack.

[0018] In one embodiment, the alloy comprises at least 5.0 atomic percent rhodium, preferably at least 10.0 atomic percent rhodium, and more preferably at least 15.0 atomic percent rhodium, which combines a high melting point with a low density and improved corrosion resistance.

[0019] In one embodiment, the alloy comprises at least 2.0 atomic percent palladium, preferably at least 5.0 atomic percent palladium, and more preferably at least 8.0 atomic percent palladium, which increases entropy and improves high temperature strength and creep resistance.

[0020] In one embodiment, the alloy comprises at least 3.0 atomic percent platinum, preferably at least 7.0 atomic percent platinum, and more preferably at least 12.0 atomic percent platinum. Such alloys may have improved corrosion resistance and may be particularly compatible with alloys coated with protective layers comprising platinum.

[0021] In one embodiment, the alloy comprises up to 10.0 atomic percent platinum, preferably up to 5.0 atomic percent platinum, more preferably up to 1.5 atomic percent platinum, even more preferably up to 1.0 atomic percent platinum, and even more preferably up to 0.5 atomic percent platinum, such alloys exhibit low VEC and improved ductility.

[0022] In one embodiment, the alloy comprises 34.0 atomic % or less tungsten, preferably 30.0 atomic % or less tungsten, more preferably 29.0 atomic % or less tungsten, even more preferably 25.0 atomic % or less tungsten, even more preferably 20.0 atomic % or less tungsten, even more preferably 15.0 atomic % or less tungsten, and most preferably 10.0 atomic % or less tungsten. Such alloys have low density.

[0023] In one embodiment, the alloy includes at least 2.0 atomic percent vanadium, preferably at least 5.0 atomic percent vanadium, and preferably at least 8.0 atomic percent vanadium, which provides improved high temperature strength and creep resistance, and good ductility without significantly increasing density or decreasing melting point, while still being low enough to reduce the risk of intermetallic phase formation.

[0024] In one embodiment, the alloy comprises at least 2.0 atomic percent tungsten, preferably at least 5.0 atomic percent tungsten, preferably at least 8.0 atomic percent tungsten, and more preferably at least 11.0 atomic percent tungsten, which provides an increased melting point, strength, and creep resistance.

[0025] In one embodiment, the alloy contains no more than 6.5 atomic percent iron, preferably no more than 3.0 atomic percent iron, and most preferably no more than 1.0 atomic percent iron, which reduces the likelihood of intermetallic phases forming.

[0026] In one embodiment, the alloy comprises less than or equal to 3.0 atomic percent silicon, preferably less than or equal to 1.0 atomic percent silicon, and more preferably 0 atomic percent silicon. Such alloys have a reduced likelihood of silicide formation, resulting in improved toughness.

[0027] In one embodiment, the alloy comprises 1.0 atomic percent or more silicon, preferably 2.0 atomic percent or more silicon, and more preferably 3.0 atomic percent or more silicon, which provides improved strength.

[0028] In one embodiment, the alloy contains up to 8.0 atomic percent nickel, preferably up to 3.0 atomic percent nickel, and more preferably up to 1.0 atomic percent nickel, which provides a low VEC and improved ductility.

[0029] In one embodiment, the alloy comprises up to 35.0 atomic percent titanium, preferably up to 34.0 atomic percent titanium, more preferably up to 33.0 atomic percent titanium, even more preferably up to 32.0 atomic percent titanium, and even more preferably up to 25.0 atomic percent titanium, which reduces the likelihood of intermetallic phases forming.

[0030] In one embodiment, the alloy contains at least 5.0 atomic percent titanium, preferably at least 8.0 atomic percent titanium, more preferably at least 13.0 atomic percent titanium, most preferably at least 20.0 atomic percent titanium, and even more preferably at least 30.0 atomic percent titanium, resulting in a low density.

[0031] In one embodiment, the alloy comprises less than or equal to 32.8 atomic percent tantalum, preferably less than or equal to 29.0 atomic percent tantalum, more preferably less than or equal to 25.0 atomic percent tantalum, even more preferably less than or equal to 22.4 atomic percent tantalum, even more preferably less than or equal to 20.0 atomic percent tantalum, even more preferably less than or equal to 15.0 atomic percent tantalum, and preferably less than or equal to 10.0 atomic percent tantalum. Such alloys offer reduced cost and density.

[0032] In one embodiment, the alloy comprises at least 2.0 atomic percent tantalum, preferably at least 5.0 atomic percent tantalum, preferably at least 10.0 atomic percent tantalum, more preferably at least 15.0 atomic percent tantalum, and most preferably at least 20.0 atomic percent tantalum, which provides improved high temperature strength.

[0033] In one embodiment, the alloy comprises not more than 30.0 atomic percent niobium, preferably not more than 25.0 atomic percent niobium, more preferably not more than 20.0 atomic percent niobium, even more preferably not more than 18.0 atomic percent niobium, even more preferably not more than 12.0 atomic percent niobium, and even more preferably not more than 10.0 atomic percent niobium, which reduces the ability to form intermetallic compounds, especially when high levels of chromium are present.

[0034] In one embodiment, the alloy comprises at least 4.0 atomic percent ruthenium, preferably at least 11.0 atomic percent ruthenium, more preferably at least 18.0 atomic percent ruthenium, and even more preferably at least 22.0 atomic percent ruthenium. Such alloys have a high melting point, which allows for high strength, reasonable density, and cost.

[0035] In one embodiment, the alloy comprises up to 18.0 atomic percent ruthenium, preferably up to 10.0 atomic percent ruthenium, more preferably up to 8.5 atomic percent ruthenium, and even more preferably up to 1.0 atomic percent ruthenium, such alloys exhibit low VEC and improved ductility.

[0036] In one embodiment, the alloy comprises at least 5.0 atomic percent niobium, preferably at least 8.0 atomic percent niobium, more preferably at least 10.0 atomic percent niobium, preferably at least 12.0 atomic percent niobium, and most preferably at least 18.0 atomic percent niobium. Such alloys have high melting points, which provide high high temperature strength and creep resistance, as well as advantages for certain types of processing.

[0037] In one embodiment, the alloy comprises up to 20.0 atomic % molybdenum, preferably up to 16.0 atomic % molybdenum, preferably up to 15.0 atomic % molybdenum, preferably up to 14.0 atomic % molybdenum, more preferably up to 12.0 atomic % molybdenum, and even more preferably up to 7.0 atomic % molybdenum, which provides improved oxidation resistance.

[0038] In one embodiment, the alloy comprises at least 2.0 atomic percent molybdenum, preferably at least 4.0 atomic percent molybdenum, more preferably at least 6.0 atomic percent molybdenum, even more preferably at least 8.0 atomic percent molybdenum, even more preferably at least 10.0 atomic percent molybdenum, and most preferably at least 12.0 atomic percent molybdenum, which provides an elevated melting point and therefore improved high temperature strength and creep resistance.

[0039] In one embodiment, the alloy contains at least 0.5 atomic percent nickel, preferably at least 2.0 atomic percent nickel, and more preferably at least 4.0 atomic percent nickel, which increases entropy (improving manufacturability, strength, and creep resistance) without significantly decreasing melting point or density.

[0040] In one embodiment, the alloy contains at least 0.5 atomic percent iron, preferably at least 2.0 atomic percent iron, and more preferably at least 4.0 atomic percent iron. Such alloys increase entropy and decrease density. Higher chromium content alloys also improve printability.

[0041] In one embodiment, the alloy comprises at least 1.0 atomic percent hafnium, preferably at least 3.0 atomic percent hafnium, and more preferably at least 5.0 atomic percent hafnium, which is preferred due to hafnium's oxygen scavenging properties and its effect in lowering the ductile-to-brittle transition temperature.

[0042] In one embodiment, the alloy includes at least 2.0 atomic percent tungsten, preferably at least 5.0 atomic percent tungsten, more preferably at least 8.0 atomic percent tungsten, and even more preferably at least 11.0 atomic percent tungsten, which increases the melting point and therefore improves high temperature strength and creep resistance.

[0043] In one embodiment, the alloy contains at least 1.0 atomic percent aluminum, preferably at least 4.0 atomic percent aluminum, more preferably at least 7.0 atomic percent aluminum, and even more preferably at least 10.0 atomic percent aluminum, which provides reduced VEC and entropy, as well as reduced density.

[0044] In one embodiment, the alloy comprises at least 2.0 atomic percent zirconium, preferably at least 4.0 atomic percent zirconium, more preferably at least 6.0 atomic percent zirconium, even more preferably at least 8.0 atomic percent zirconium, even more preferably at least 10.0 atomic percent zirconium, and most preferably at least 12.0 atomic percent zirconium, resulting in high ductility and low density.

[0045] In one embodiment, the alloy contains up to 15.0 atomic percent cobalt, preferably up to 10.0 atomic percent cobalt, and more preferably up to 7.0 atomic percent cobalt, which provides a low VEC and improved ductility.

[0046] In one embodiment, the alloy comprises at least 0.5 atomic percent cobalt, preferably at least 1.0 atomic percent cobalt, more preferably at least 2.0 atomic percent cobalt, even more preferably at least 3.0 atomic percent cobalt, and most preferably at least 4.0 atomic percent cobalt, which reduces the likelihood of forming intermetallic phases with little adverse effect on cost, density, or melting point.

[0047] In one embodiment, the alloy contains up to 10.0 atomic percent copper, preferably up to 5.0 atomic percent copper, and more preferably up to 2.0 atomic percent copper, which provides a low VEC and improved ductility.

[0048] In one embodiment, the alloy contains at least 0.5 atomic percent copper, preferably at least 1.0 atomic percent copper, more preferably at least 2.0 atomic percent copper, and even more preferably at least 3.0 atomic percent copper, which increases entropy and improves phase stability, strength, and creep resistance.

[0049] In one embodiment, the alloy comprises at least 0.5 atomic percent chromium, preferably at least 2.0 atomic percent chromium, and more preferably at least 4.0 atomic percent chromium, which provides improved printability, especially when combined with iron.

[0050] In one embodiment, the alloy contains at least 0.5 atomic percent manganese, preferably at least 2.0 atomic percent manganese, and more preferably at least 4.0 atomic percent manganese, which provides increased entropy, improved phase stability, strength and creep resistance, and lower density.

[0051] In one embodiment, the alloy contains up to 30.0 atomic percent manganese, preferably up to 23.0 atomic percent manganese, more preferably up to 15.0 atomic percent manganese, and most preferably up to 1.0 atomic percent manganese, which provides a low VEC and improved ductility.

[0052] In one embodiment, the alloy includes at least 3.0 atomic percent rhenium, preferably at least 5.0 atomic percent rhenium, more preferably at least 8.0 atomic percent rhenium, even more preferably at least 15.0 atomic percent rhenium, even more preferably at least 20.0 atomic percent rhenium, and most preferably at least 25.0 atomic percent rhenium, which provides improved high temperature strength and creep resistance.

[0053] In one embodiment, the alloy comprises less than or equal to 28.0 atomic percent rhenium, preferably less than or equal to 22.0 atomic percent rhenium, more preferably less than or equal to 20.0 atomic percent rhenium, more preferably less than or equal to 15.0 atomic percent rhenium, more preferably less than or equal to 14.5 atomic percent rhenium, more preferably less than or equal to 10.0 atomic percent rhenium, more preferably less than or equal to 5.0 atomic percent rhenium, more preferably less than or equal to 1.0 atomic percent rhenium. Such alloys provide low cost.

[0054] In one embodiment, the alloy includes up to 5.5 atomic percent hafnium, preferably up to 1.0 atomic percent hafnium, which reduces costs.

[0055] In one embodiment, the following equation is satisfied:

number

[0056] Such alloys have improved ductility.

[0057] In one embodiment, the following equation is satisfied: A W +0.8A Ta ≦43 Preferably, A W +0.8A Ta ≦34 More preferably, A W +0.8A Ta ≦29 Most preferably, A W +0.8A Ta ≦20 where A Ta and A W are the atomic percentages of tantalum and tungsten, respectively, in the alloy. Such alloys have low density.

[0058] In one embodiment, the following equation is satisfied: A Re +0.67A Ta ≦35 Preferably, A Re +0.67A Ta ≦28 More preferably, A Re +0.67A Ta ≦22 Most preferably, A Re +0.67A Ta ≦15 where A Re and A Ta are the atomic percentages of rhenium and tantalum, respectively, in the alloy. Such alloys have low density.

[0059] In one embodiment, the following equation is satisfied: A Al +A Zr +A Ti +A Si +A Hf ≧16.5 Preferably, A Al +A Zr +A Ti +A Si +A Hf ≧31.5 where A Al , A Zr , A Si , A Hf , A Ti are the atomic percentages of aluminum, zirconium, silicon, hafnium, and titanium, respectively, in the alloy. Such alloys have improved ductility.

[0060] In one embodiment, the following equation is satisfied: A V +2A Ta ≦40 Preferably, A V +A Ta ≦20 Preferably, A V +A Ta ≦15 Preferably, A V +2A Ta ≦20 where A V and A Ta are the atomic percentages of vanadium and tantalum, respectively, in the alloy. Such alloys offer reduced costs.

[0061] In one embodiment, the alloy comprises less than or equal to 14.0 atomic percent chromium, preferably less than or equal to 13.0 atomic percent chromium, more preferably less than or equal to 7.7 atomic percent chromium, even more preferably less than or equal to 7.0 atomic percent chromium, and most preferably less than or equal to 2.0 atomic percent chromium, which reduces the likelihood of intermetallic compound formation and therefore improves ductility.

[0062] In one embodiment, the following equation is satisfied: 15≦A W +A Ta +A Mo +A Nb +A Re Preferably, 25≦A W +A Ta +A Mo +A Nb +A Re More preferably, 0.6A Al +25≦A W +A Ta +A Mo +A Nb +A Re Even more preferably, 1.2A Al +30≦A W +A Ta +A Mo +A Nb +A Re Most preferably, 0.8A Al +47≦A W +A Ta +A Mo +A Nb +A Re where A W , A Al , A Ta , A Mo , A Re , A Nb are the atomic percentages of tungsten, aluminum, tantalum, molybdenum, rhenium, and niobium, respectively, in the alloy. Such alloys have elevated melting points, which improve high-temperature strength and creep resistance.

[0063] The term "comprising" is used herein to indicate that the composition is 100% and that the percentage is made up to 100% to the exclusion of the presence of additional components. Unless otherwise specified, all amounts are expressed as atomic % (at%). i is the atomic percentage of element i in the alloy, and x i is the atomic fraction of element i in the alloy.

[0064] The present invention will now be more fully described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0065] [Figure 1a] All alloys within the region defined in Table 2 are plotted, without further restriction, with Co on the y-axis and VEC on the x-axis. [Figure 1b] All alloys within the region defined in Table 2 are plotted, without further restriction, with Cu on the y-axis and VEC on the x-axis. [Figure 1c] All alloys within the region defined in Table 2 are plotted, without further restriction, with Ni on the y-axis and VEC on the x-axis. [Figure 1d] All alloys within the region defined in Table 2 are plotted, without further restriction, with Ir on the y-axis and VEC on the x-axis. [Figure 1e] All alloys within the region defined in Table 2 are plotted, without further restriction, with Pd on the y-axis and VEC on the x-axis. [Figure 1f] All alloys within the region defined in Table 2 are plotted, without further restriction, with Pt on the y-axis and VEC on the x-axis. [Figure 1g] All alloys within the region defined in Table 2 are plotted, without further restriction, with Rh on the y-axis and VEC on the x-axis. [Figure 1h] All alloys within the region defined in Table 2 are plotted, without further restriction, with Ru on the y-axis and VEC on the x-axis. [Figure 2] The zirconium concentration and whether Al-Zr intermetallic compounds are present are indicated. [Figure 3] It indicates the iron concentration and whether Fe-Ti intermetallic compounds are present. [Figure 4a]The density of the alloy is plotted as a function of W and Ta content, with a line drawn for density ≤ 11 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 4b] The density of the alloy is plotted as a function of W and Ta content, with a line drawn for density ≤ 10 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 4c] The density of the alloy is plotted as a function of W and Ta content, with a line drawn for density ≤ 9 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 4d] The density of the alloy is plotted as a function of W and Ta content, with a line drawn for density ≤ 8 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 5a] The density of the alloys is plotted as a function of Re and Ta content, with a line drawn for density ≤ 11 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 5b] The density of the alloys is plotted as a function of Re and Ta content, with a line drawn for density ≤ 10 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 5c] The density of the alloys is plotted as a function of Re and Ta content, with a line drawn for densities ≤ 9 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 5d]The density of the alloys is plotted as a function of Re and Ta content, with a line drawn for density ≤ 8 g / cm3. The alloy region is the broadest elemental region defined in Table 10, which also includes the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 6] VEC is plotted on the y-axis against Al equivalent (the sum of Al, Zr, Ti, Hf, and Si). The alloys plotted fall within the scope of claim 1, including the constraints of VEC≦5.0 and entropy≧13.38. [Figure 7a] Figure 7a plots melting points as a function of tungsten equivalent (Weq, the sum of tungsten, tantalum, molybdenum, niobium, and rhenium) and aluminum atomic %. The alloy region is the broadest elemental region defined in Table 10, including the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. Figure 7a plots all alloys with melting points above 2200 K. [Figure 7b] Figure 7b plots melting points as a function of tungsten equivalent (Weq, the sum of tungsten, tantalum, molybdenum, niobium, and rhenium) and aluminum atomic %. The alloy region is the broadest elemental region defined in Table 10, including the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. Figure 7b plots all alloys with melting points above 2400 K. [Figure 7c] Figure 7c plots melting points as a function of tungsten equivalent (Weq, the sum of tungsten, tantalum, molybdenum, niobium, and rhenium) and aluminum atomic %. The alloy region is the broadest elemental region defined in Table 10, including the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. Figure 7c plots all alloys with melting points above 2500 K. [Figure 7d]Figure 7d plots melting points as a function of tungsten equivalent (Weq, the sum of tungsten, tantalum, molybdenum, niobium, and rhenium) and aluminum atomic %. The alloy region is the broadest elemental region defined in Table 10, including the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. Figure 7d plots all alloys with melting points above 2600 K. [Figure 7e] Figure 7e plots melting points as a function of tungsten equivalent (Weq, the sum of tungsten, tantalum, molybdenum, niobium, and rhenium) and aluminum atomic %. The alloy region is the broadest elemental region defined in Table 10, including the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. Figure 7e plots all alloys with melting points above 2800 K. [Figure 8] The density vs. melting point tradeoff is shown for all alloys within the broadest elemental region defined in Table 10 and including the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 9a] All alloys within the broadest elemental region defined in Table 10 and containing the constraints of VEC ≤ 5.0 and entropy ≥ 13.38 are plotted with Ir on the y-axis and cost on the x-axis. [Figure 9b] All alloys within the broadest elemental region defined in Table 10 and containing the constraints of VEC ≤ 5.0 and entropy ≥ 13.38 are plotted with Rh on the y-axis and cost on the x-axis. [Figure 9c] Pd is plotted on the y-axis against cost on the x-axis for all alloys that fall within the broadest elemental region defined in Table 10 and that include the constraints of VEC ≤ 5.0 and entropy ≥ 13.38. [Figure 9d] All alloys within the broadest elemental region defined in Table 10 and containing the constraints of VEC≦5.0 and entropy ≧13.38 are plotted with Pt on the y-axis and cost on the x-axis. [Figure 9e] Re is plotted on the y-axis against cost on the x-axis for all alloys that fall within the broadest elemental region defined in Table 10 and that include the constraints of VEC≦5.0 and entropy ≧13.38. [Figure 9f] All alloys within the broadest elemental region defined in Table 10 and containing the constraints of VEC≦5.0 and entropy ≧13.38 are plotted with Ru on the y-axis and cost on the x-axis. [Figure 10a] The relationship between cost and the concentrations of Ta and V is shown. This alloy is within the broadest elemental region defined in Table 10 and includes the constraints of VEC≦5.0 and entropy≧13.38. [Figure 10b] The relationship between cost and the concentrations of Ta and V is shown. This alloy is within the broadest elemental region defined in Table 10 and includes the constraints of VEC≦5.0 and entropy≧13.38. [Figure 10c] The relationship between cost and the concentrations of Ta and V is shown. This alloy is within the broadest elemental region defined in Table 10 and includes the constraints of VEC≦5.0 and entropy≧13.38. [Figure 10d] The relationship between cost and the concentrations of Ta and V is shown. This alloy is within the broadest elemental region defined in Table 10 and includes the constraints of VEC≦5.0 and entropy≧13.38. [Figure 10e] The relationship between cost and the concentrations of Ta and V is shown. This alloy is within the broadest elemental region defined in Table 10 and includes the constraints of VEC≦5.0 and entropy≧13.38. DETAILED DESCRIPTION OF THE INVENTION

[0066] ABD design steps Traditionally, high-performance alloy materials have been designed empirically, whereby their chemical compositions have been identified using time-consuming and expensive experimental development involving small-scale processing of limited amounts of material followed by operational characterization. The alloy composition adopted is the one found to exhibit the best or most desirable combination of properties.

[0067] In the field of CCA and RCCA, modeling techniques provide new insights that can be applied to identify improved alloys, as removing major elements allows for a vast number of alloy combinations.

[0068] Here, we describe a modeling-based approach used to identify optimized CCAs, referred to as the "Alloys-By-Design" (ABD) method. This approach uses a computational materials model framework to estimate design-relevant properties over a very wide compositional range. In principle, this alloy design tool can be used to solve a so-called inverse problem: identifying the optimal alloy composition that best satisfies a specified set of design constraints.

[0069] The first step in the design process is to define the list of elements and their associated upper and lower compositional limits. The compositional limits for each elemental addition (called the "alloy design space") considered in this invention are detailed in Table 2.

[0070] The starting point is that at least three different elements must be present (although at least four elements may be necessary to ensure sufficient entropy), meaning each element can be present up to 35 atomic percent. Titanium can be increased to 40 atomic percent because it is important for reducing the valence electron concentration (VEC), as described below. The only elements that reduce VEC are aluminum, zirconium, silicon, hafnium, and titanium. However, aluminum has a very low melting point compared to the refractory elements, so too much aluminum can reduce workability. Zirconium is limited to reduce the likelihood of intermetallic phase formation. Silicon and hafnium also form deleterious secondary phases. Therefore, of these elements, titanium is the only one that can be used in very large quantities to reduce VEC. If a very high-entropy alloy is required, the amount of titanium can be reduced to 35.0 atomic percent or less.

[0071] Certain elements are limited to 35.0 atomic percent or less based on an understanding of their potential practical effects, particularly the promotion of intermetallic compound formation.

[0072] In RCCA systems, high-entropy effects promote the formation of solid solutions with lower intermetallic fractions than would be expected from binary and ternary subsystems of composition. Most solidification routes for processing RCCA alloys tend to result in microsegregation. In regions where this effect is most pronounced, such as interdendritic regions, element concentrations can become extremely high and the entropy can fall below the critical value for microstructural stability. This increases the likelihood of intermetallic formation.

[0073] To ensure that the alloys encompassed by this invention remain resistant to the formation of intermetallic compounds during solidification that induce segregation, additional restrictions are placed on the elements most susceptible to secondary phase formation. These elements include chromium, hafnium, zirconium, iron, and vanadium.

[0074] Based on XRD and EBSD measurements of prior art alloys, compositions containing both chromium and niobium tend to form a C14 Laves phase based on Cr2Nb stoichiometry when the chromium content is 18 atomic percent or greater (Ma and Zhang, 2012; Senkov et al., 2013; Chen et al., 2016). Introducing this phase into an alloy at a volume fraction of 0.1 has been shown to reduce the plastic strain limit of an HEA system by 50% (Ma and Zhang, 2012). To maximize the ductility of the alloy, the formation of this phase must be minimized. According to the Cr-Nb phase diagram, the maximum solubility limit of chromium in niobium is 15 atomic percent at 1650°C, beyond which significant amounts of Cr2Nb are formed (Massalski and Okamoto, 1990). Therefore, a maximum chromium content of 15.0 atomic percent or less is permitted in the present invention. To reduce the supply of chromium atoms for intermetallic compound formation, the chromium content is preferably 14.0 atomic % or less, and even more preferably 13.0 atomic % or less. XRD and ESBD revealed that an alloy containing 7.7 atomic % chromium and 15.4 atomic % niobium does not form the CrNb phase (Sheikh et al., 2020). Therefore, in the present invention, the chromium content is even more preferably 7.7 atomic % or less. The solubility of chromium in niobium further decreases with decreasing temperature, reaching 7.0 atomic % at 1300°C and 2.0 atomic % at 1000°C. Therefore, to improve resistance to CrNb formation over a wider temperature range, the chromium content is more preferably 7.0 atomic % or less, and even more preferably 2.0 atomic % or less. In one embodiment, chromium is absent except at unavoidable impurity levels.

[0075] Hafnium is not a major element in the compositional range due to its difficulty in sourcing, but its ability to trap oxygen and lower the ductile-to-brittle transition temperature can provide useful properties for RCCA (Tsakiropoulos, 2022). Based on the Hf-Nb phase diagram, hafnium levels greater than 10.0 atomic percent promote the formation of a second hafnium-rich phase. Therefore, hafnium should be present at levels of 10.0 atomic percent or less. The high-temperature niobium alloy C103 has a composition of Nb-10Hf-1Ti (by mass), which corresponds to 5.5 atomic percent hafnium. Therefore, hafnium is preferably present at levels of 5.5 atomic percent or less. Experiments have shown that such alloys have an appropriate microstructure and low cost. Preferably, hafnium is present at levels of 1.0 atomic percent or less.

[0076] The presence of zirconium is known to lead to the formation of intermetallic compounds with aluminum (Soni et al., 2018; Tsai et al., 2019). Limiting the zirconium concentration can reduce the formation of intermetallic compounds. Tsai et al. (2019) reported that a Zr content of 16.7 atomic percent leads to the formation of Zr intermetallic compounds. Based on this, to suppress the formation of AlZr-based phases, the zirconium content is limited to 16.7 atomic percent or less. The zirconium content is preferably 16.0 atomic percent or less, more preferably 15.0 atomic percent or less, even more preferably 14.0 atomic percent or less, and even more preferably 13.0 atomic percent or less.

[0077] It is known that the presence of iron leads to the formation of the intermetallic compound Fe2Ti with titanium (Tsai et al., 2019). This phase is very brittle, and its presence in the microstructure reduces the ductility of the alloy (Wang et al., 2007; Zhou et al., 2007). Based on reported alloys, Fe2Ti can be reduced by keeping the iron content below 15.4 atoms.

[0078] Based on the vanadium-tantalum phase diagram, when the vanadium concentration exceeds 12.0 atomic percent, the formation of the C14 and C15 Laves phases becomes thermodynamically favored (Bale et al., 2016). Therefore, the vanadium concentration must be limited to 12.0 atomic percent or less. To further reduce the availability of vanadium atoms for the formation of intermetallic compounds, the vanadium content is preferably even lower, such as 6.0 atomic percent or less, or even 1.0 atomic percent or less. In one embodiment, if the alloy is to have extremely high resistance to the formation of intermetallic compounds, it is preferable that vanadium be absent except at unavoidable impurity levels.

[0079] The alloys of the present invention are desirably easily processable by melting, sintering, a combination of both, or other methods. These are approaches similar to those applied to commercially available refractories and nickel alloys (e.g., C103, FS-85, IN718, CMSX-4). Desirably, the RCCA of the present invention can be easily substituted into existing processes. Regardless of the method used to manufacture the alloy, a combination of individual elements is required. Achieving a homogeneous alloy becomes difficult when combining high concentrations of aluminum (which has the lowest melting point within the design domain) with high levels of refractory elements (e.g., W, Re, Ta, Nb, Mo) that have very high melting points. Due to the high strength of the RCCA of the present invention, machining them is time-consuming and costly. Therefore, they are ideally suited for near-net-shape processing methods, including, but not limited to, casting, additive manufacturing (AM), and hot isostatic pressing (HIP).

[0080] During arc melting and other casting processes, aluminum melts much faster than refractory elements during heating. For alloys with particularly high aluminum content, the melt temperature does not always reach a high enough temperature to completely dissolve elements such as tungsten. This results in unmelted areas of material that must be remelted or discarded. The EIGA atomization process is the preferred method for producing raw powders for additive manufacturing and HIP. Powder production tests have shown that combining high concentrations of refractory elements with high concentrations of aluminum results in insufficient sintering during EIGA electrode production. This is because the temperatures required for effective sintering of the refractory elements (>1200°C) are typically higher than the melting point of aluminum (660°C). One alloy that experiences this problem is RHG2E (22Al9Zr5W5Cr35Ti5Ta19Nb at.%). These alloys are primarily intended for use in vacuum, inert atmospheres, or with special oxidation-resistant coatings, so the formation of a continuous alumina scale is not necessary. Therefore, the aluminum content can be less than 20.0 at. To avoid melting and sintering problems, the present invention requires that the aluminum content be 19.45 atomic % or less, preferably 19.0 atomic % or less, more preferably 15.0 atomic % or less, even more preferably 10.0 atomic % or less, and even more preferably 5.0 atomic % or less.

[0081] In one embodiment, it is preferred that no aluminum be present in the alloy except at unavoidable impurity levels.

[0082] The primary refractory elements in this invention (Mo, Nb, Re, Ta, Ti, V, W, and Zr) have low solubilities in silicon (3, 5, 10, 5, 5, 7, 4, and 0 atomic %, respectively). Beyond their solubility limits, silicide phases such as M3Si can form. At low volume fractions, these silicide phases can significantly increase yield strength. However, silicides fracture brittle, so high volume fractions or a continuous network of phases throughout the microstructure can have a significant adverse effect on fracture toughness. To avoid excessive silicide formation, the Si concentration must be kept below 5.0 atomic %, which corresponds to the limits for Nb, Ta, and Ti. Preferably, silicon is below 3.0 atomic %, more preferably below 1.0 atomic %, and most preferably 0 atomic % (e.g., the level of an unavoidable impurity), thereby eliminating the possibility of forming highly brittle silicides.

[0083] Table 2 shows the alloy design space, in atomic percent, searched using the "Alloys-by-Design" method. [Table 2]

[0084] Alloy selection depends on calculating the alloy's figures of merit within the alloy composition range (as shown in Table 2). Examples of these figures of merit include entropy (related to the tendency of elements in the alloy to form solid solution structures, and therefore related to strength and creep resistance), valence electron concentration (related to resistance to intermetallic phase formation and good ductility), melting point index, density, and cost.

[0085] In the second stage, the calculated figures of merit over the entire region defined in Table 2 are compared to the desired behavioral constraints on configurational entropy and valence electron concentration, and these design constraints are considered boundary conditions for the problem. All compositions that do not satisfy the boundary conditions are eliminated. In this stage, the size of the alloy region is reduced.

[0086] In the third stage, the remaining compositional data set was analyzed to identify sample compositions with favorable figures of merit compared to conventional alloys. Further restrictions on the alloy range were imposed as a result of experimental observations.

[0087] Merit Index Explained Next, the sample merit figure will be described.

[0088] The first figure of merit is the entropy index. A sufficiently high entropy of mixing of a solid solution improves the stability of the solid solution against the formation of intermetallic phases. This stability can often be extended to high temperatures, improving ease of processing. The entropy is given by:

number

[0089] where x i is the atomic fraction of element i in the alloy and R is the universal gas constant.

[0090] The solid solution structure of RCCA is stabilized by high entropy effects, which result in a significantly simplified microstructure compared to that expected from binary and ternary systems of composition. The entropy of RCCA is dominated by configurational entropy. There are many competing definitions for the threshold of configurational entropy at which an alloy is considered a high-entropy alloy and enjoys high-entropy effects. The first definition states that the value of configurational entropy is equal to or greater than 1.5R(12.47), where R is the universal gas constant, which has a value of 8.3145 JK. -1 mol -1(Murty et al., 2019). A further definition is that, based on an alloy composed of five or more major elements in equiatomic ratios, the configurational entropy value is ln(5)R(13.38) or greater (Yeh, 2013). Some HEA compositions studied are equiatomic and pentaatomic, including, but not limited to, RHEA1 and RHEA3 in Table 1. These compositions have been reported to benefit from high-entropy effects, and their configurational entropy provides a promising starting point for improvement (Miracle et al., 2011; Gorr et al., 2017). Therefore, in the present invention, a configurational entropy of 13.38 or greater is required. More preferably, to further improve these properties, an entropy of 13.5 or greater is required. This further enhances the stability of the solid solution and increases lattice distortion and slow diffusion, thereby enhancing strength and creep resistance, respectively. As can be seen from Table 7 below, alloys with configurational entropy of 13.8 or greater have been designed and are preferred.

[0091] In one embodiment, the alloy is substantially single-phase, i.e., a single matrix in which all elements are in solid solution. That is, the alloy is substantially free of intermetallic phases (e.g., carbides, oxides, borides), and the maximum volume fraction of intermetallic phases (as measured by optical microscopy) is 5% or less (typically 2% maximum carbides, 1% maximum oxides, and 1-2% borides). CN109252082 indicates that carbide phases are detected by XRD analysis, with the carbide volume fraction exceeding 10% (10% being the typical lower limit of XRD detection).

[0092] The second figure of merit is the valence electron concentration index, which represents the number of outer electrons in an atom and is given by:

number

[0093] where x i is the atomic fraction of element i in the alloy bulk composition, VEC iis the valence electron concentration of element i (Miracle and Senkov, 2017). A low VEC indicates that the alloy is composed mainly of the BCC phase and therefore has high ductility. The number of electrons in the outer shell is shown in Table 3 below.

[0094] Valence electron concentration has been reported to be a good predictor of crystal structure in high-entropy alloys (Tsai et al., Criterion for sigma phase generation in Cr- and V-containing high-entropy alloys. Mater. Res. Lett. 2013,1, 207-212). Here, a VEC < 6.87 corresponds to a sigma-free alloy composed primarily of BCC phase. It has also been reported that further restricting the VEC can improve the intrinsic ductility of single-phase BCC high-entropy alloys (Sheikh et al., 2016). No brittle behavior was observed at VEC < 4.60. In this study, additional elemental restrictions (for Cr, Zr, and Fe) were used to restrict the formation of certain intermetallic compounds and improve the ductility of the alloy. The power of these restrictions is demonstrated in the following examples. NbMoCrTiAl has been experimentally observed to form the CrNb Laves phase with a chromium content of 20 atomic percent and a VEC of 4.8 (Muller et al., 2019). Another alloy, RHG3F, has a similar VEC of 4.9 but a significantly lower chromium content of 5 atomic percent. Experimentally, it has been observed to lack Laves phases. Therefore, by limiting the amount of intermetallic compound-forming elements such as Cr, Zr, and Fe, as in the present invention, the VEC requirement can be relaxed to VEC ≤ 5.00. A VEC of 5.00 or less is a design requirement of the present invention. A VEC of 4.90 or less is preferred, with a VEC of 4.80 or less being more preferred, and a VEC of 4.70 or less being even more preferred. In one embodiment, even lower VECs, such as 4.60, 4.40, or even 4.20, are preferred.

[0095] The third figure of merit is the melting point index. A high melting point is necessary for high-temperature applications to avoid melting the alloy. A high melting point also maximizes high-temperature strength and creep resistance. The melting point, Tm, is given by the following formula:

number

[0096] The fourth figure of merit is density. Density ρ was calculated using a simple rule of mixtures, where ρ i is the density of a given element, x i is the atomic fraction of the alloying element. Table 3 shows the densities of the relevant elements.

number

[0097] The fifth figure of merit is cost. To estimate the cost of each alloy, we multiply the atomic fraction of the alloying element by x i , the current (2021) raw material cost of alloying elements c i A simple mixing rule was applied: multiply by (USD / mol).

number

[0098] This estimate assumes that processing costs are the same for all alloys, i.e., product yields are not affected by composition. Table 3 shows the costs of all relevant elements. [Table 3]

[0099] The ABD method described above was used to identify alloy compositions that met the entropy and VEC requirements described above and also exhibited other promising properties as defined by figures of merit 3 through 5. The compositional limits defined in Table 2 apply.

[0100] Of the elements in Table 2, cobalt, copper, nickel, iridium, palladium, platinum, rhodium, and ruthenium have the highest VECs. Figure 1 is a series of plots showing alloys within the range of Table 2. The y-axis shows the amount of a particular element, and the x-axis shows the VEC. Referring to Figure 1, to achieve a VEC of 5.00 or less, the concentrations of these elements in the alloy must be kept below the following values ​​to ensure ductility: A Co ≦20.0, A Cu ≦15.0, A Ni ≦15.0, A Ir ≦20.0, A Pd ≦15.0, A Pt ≦15.0, A Rh ≦20.0, A Ru ≦25.0

[0101] where A Co , A Cu , A Ni , A Ir , A Pd , A Pt , A Rh , A Ruare the atomic percentages of cobalt, copper, nickel, iridium, palladium, platinum, rhodium, and ruthenium, respectively, in the alloy. To achieve even lower VEC levels, further reductions in the contents of these elements are preferred. Therefore, copper is preferably maintained at levels of 10.0 atomic % or less, more preferably 5.0 atomic % or less, and even more preferably 2.0 atomic % or less. Cobalt is maintained at levels of 15.0 atomic % or less in preferred embodiments, 10.0 atomic % or less in even more preferred embodiments, and most preferably 7.0 atomic % or less. For the same reasons, nickel is preferably kept low, for example, at levels of 8.0 atomic % or less, or 3.0 atomic % or less, or even 1.0 atomic % or less. Iridium and rhodium are preferably maintained at levels of 15.0 atomic % or less, more preferably 8.0 atomic % or less, and even 1.0 atomic % or less. Palladium and platinum are preferably maintained at levels of 10.0 atomic % or less, more preferably 5.0 atomic % or less or 1.0 atomic % or less to keep costs low. Ruthenium is preferably maintained at levels of 18.0 atomic % or less, more preferably 10.0 atomic % or less. In one embodiment, it is preferred to remove all of these high VEC elements (e.g., to the level of unavoidable impurities).

[0102] Modeling results indicate that a VEC ≤ 5.00 is achievable for Al, Cr, Fe, Hf, Mn, Mo, Nb, Re, Si, Ta, Ti, V, W, and Zr throughout the ranges in Table 2 and therefore these were assumed to be acceptable. Therefore, for alloy design, the limits in Table 2 apply unless amounts need to be reduced to avoid intermetallic compounds.

[0103] Because this invention does not rely on oxide growth to prevent oxidation, the Pilling-Bedworth ratio of the alloy is not used as a design criterion. Therefore, rhenium, which has a high elemental Pilling-Bedworth ratio, is permitted up to 35.0 atomic percent. Nevertheless, due to the cost and high density of rhenium, it is preferable to limit the content to 35 atomic percent and substitute other refractory elements in small amounts. The melting point of rhenium is higher than that of Ta and Nb and is comparable to that of W. Therefore, rhenium can provide similar high-temperature strength to the alloy and can therefore be used in place of Ta, W, and Nb. Therefore, the permitted rhenium content is 35 atomic percent or less, and the atomic percentages of rhenium, tantalum, tungsten, and niobium are A, B, C, and D, respectively. Re , A Ta , A W and A Nb When A Re ≦(35-A Ta )+(35-A W )+(35-A Nb ) Since rhenium is very difficult to obtain, the element cost is high and the density is also high. For this reason, the rhenium content is preferably 20.0 atomic % or less, more preferably 15.0 atomic % or less, most preferably 10.0 atomic % or less, and even more preferably 5.0 atomic % or less. In order to achieve a particularly high melting point, it is preferable to sacrifice cost and density as described above, and set the minimum rhenium content to 3.0 atomic %, or even 5.0 atomic % or more.

[0104] The alloys previously investigated in Table 1 are reproduced in Table 4 for ease of reference. Examples of alloys that meet all of the above requirements are listed in Table 5, and comparative examples are listed in Table 6. Figure of merit values ​​for all benchmark alloys, examples, and comparative examples are listed in Table 7. As can be seen, it is possible to meet the compositional requirements set forth in Table 10, but not the entropy and VEC requirements. For example, RHEA8 and RHEA9 are both within the compositional range set forth in Table 10, but are not included in the present invention because their VEC exceeds 5.0. Additionally, RHEA10, RHEA11, and RHEA12 also fall within the compositional limits, but are not included in the present invention because their entropy is below 13.38. [Table 4] [Table 5] JPEG2025536324000017.jpg90170 [Table 6] [Table 7] JPEG2025536324000020.jpg87170

[0105] The RHG3 alloy was manufactured and its properties investigated. Based on the experimental results, the following additional limitations are imposed on the alloy of the present invention:

[0106] Figure 2 maps the zirconium concentration and the formation of the AlZr intermetallic phase. The alloys plotted correspond to those in Table 8 and are a combination of alloys from the Metals 2019 article and alloys experimentally fabricated and tested by the inventors. The present invention encompasses alloys with a zirconium content of 16.7 atomic % or less to avoid regions known to form AlZr intermetallics. Although RHG3J, RHG3M, and RHG3F all contain both Al and Zr, no Al-Zr intermetallic phases were observed. Therefore, it is preferred that the alloys included in the present invention contain zirconium at 12.4 atomic % or less (i.e., lower levels than RHG3J and RHG3F, which do not contain AlZr intermetallics) or 5.0 atomic % or less. [Table 8]

[0107] Figure 3 maps the relationship between iron concentration and the formation of the Fe2Ti intermetallic phase. The alloys plotted correspond to those in Table 9, a combination of alloys from the Metals 2019 article and alloys experimentally fabricated and tested by the inventors. As discussed above, keeping the iron content below 15.4 atomic percent avoids the region known to form Fe2Ti intermetallic compounds. This requirement was further tightened based on the experimental results for RHG1K to include alloys with iron contents below 6.5 atomic percent. Both RHG1H and RHG1K contain iron and titanium, but no Fe-Ti intermetallic compounds were observed. Thus, RHG1K is the alloy containing titanium with the maximum iron content such that Fe2Ti intermetallic compounds do not form. Therefore, to further reduce the iron atom supply, alloys included in this invention should contain either 6.5 atomic percent or less of iron, or 3.0 atomic percent or less. [Table 9]

[0108] When exposed to oxygen at high temperatures, vanadium can form vanadium-based oxides such as V2O5. This oxide species can form a low-melting eutectic and accelerate corrosion (Esmaily et al., 2020). The alloys of the present invention can contain vanadium at levels up to 12.0 atomic % and operate in vacuums and inert atmospheres, such as outer space, or with coating systems designed to provide oxidation and corrosion resistance. Such coatings include, but are not limited to, platinum, iridium, rhodium, ruthenium, palladium, or their alloys, disilicides, MAX phase (Ti2Al1C1), HfC, ZrC, IrHf, R512E (Si-20Cr-20Fe), or combinations of the above. These coatings inhibit the formation of vanadium oxides by preventing the diffusion of vanadium to oxygen-exposed surfaces or into vanadium-containing materials. One example of a potential coating is pure platinum diffusion-bonded to RCCA. Diffusion bonding experiments between WTaNbVMo and pure platinum confirmed that vanadium diffused through a 100 μm-thick platinum layer after annealing at 1200 °C for 100 hours. Even with a coating, V2O5 formation can lead to corrosion problems. Experiments have shown that when the alloy substrate surface is directly exposed to oxygen at high temperatures (e.g., 1300 °C for 20 hours), the vanadium content must be kept below 7.0 atomic % to avoid V2O5 formation. Platinum coatings provide further resistance to this oxidation, and experiments have shown that the vanadium concentration decreases from 20 atomic % in the substrate to 14 atomic % at the coating-air interface. This means that the platinum coating reduces the concentration in the bulk alloy by 70%. Therefore, to avoid V2O5 formation, it is preferable to keep the vanadium concentration in the alloy below 10.0 atomic % (7.0 × 100 / 70). Preferably, the alloy contains no more than 7.3 atomic percent vanadium, more preferably no more than 4.3 atomic percent vanadium.

[0109] Through the development, fabrication, and testing, five alloys—RHG3B, RHG3D, RHG3E, RHG3F, and RHG3K—were confirmed to exhibit superior performance. All five alloys exhibited very high Vickers hardness values: 628, 570, 445, 617, and 523 HV, respectively. In compression tests, all five alloys exceeded 1500 MPa in strength. RHG3B and RHG3F exhibited compressive ductility values ​​of over 4%, good for RCCA. RHG3K and RHG3E exhibited compressive ductility values ​​of over 14%, excellent for RCCA. RHG3D exceeded 2000 MPa in compressive strength, reaching the machine's load limit before fracture, so no ductility value was recorded, but its strength was excellent. All alloys were observed by SEM to be free of intermetallic phases. RHG3K exhibited minimal solidification and solid-state cracking across a wide laser parameter window, making it particularly suitable for additive manufacturing. RHG3K exhibited such an excellent combination of strength, ductility, and printability that when tested using hot hardness up to 600°C, an equivalent strength of 1090 MPa was measured, which is comparable to CM247 (1140 MPa) and far exceeds FS-85 (500 MPa) and C103 (430 MPa) at the same temperature and using the same test method. Following the decreasing trend in hot hardness, a high-temperature strength of 700 MPa at 1300°C is predicted.

[0110] It is desirable to minimize density. This is done by controlling the addition of elements with large atomic masses, particularly tungsten, tantalum, and rhenium. The relationship between tungsten and tantalum levels and predicted alloy density is shown in Figures 4a-d. A maximum target alloy density (11 g / cm) comparable to that of the literature RCCA, MoNbTaTiVW, is achieved. 3 (below) is achieved when: A W +0.8A Ta ≦43 atomic%

[0111] where A W and A Ta are the atomic percentages of tungsten and tantalum, respectively, in the alloy. Preferably, the alloy density is 10 g / cm 3or less, i.e., FS85 or less, which is achieved when: A W +0.8A Ta ≦34 atomic%

[0112] This includes A W The alloy density should be 34.0 or less. More preferably, the alloy density should be 9 g / cm 3 or less, i.e., C103 or less, which results in a lightweight part that does not require as much creep strength when used in rotating applications. This is achieved when: A W +0.8A Ta ≦29 atomic%

[0113] This includes A W The most preferable maximum alloy density is 8 g / cm 3 Below, CMSX-4 and below correspond to the following equation: A W +0.8A Ta ≦20 atomic% This includes A Ta and A W However, they must be below 25.0 and 20.0 respectively.

[0114] The relationship between rhenium and tantalum levels and predicted alloy density is shown in Figures 5a-d. The maximum target alloy density (11 g / cm) is comparable to that of the literature RCCA, MoNbTaTiVW. 3 (below) is achieved when: A Re +0.67A Ta ≦35 atomic%

[0115] where A Re and A Ta are the atomic percentages of rhenium and tantalum, respectively, in the alloy. Preferably, the alloy density is 10 g / cm 3 or less, i.e., FS85 or less, which is achieved when: A Re +0.67A Ta ≦28 atomic%

[0116] This includes A Re The alloy density should be 28.0 or less. More preferably, the alloy density should be 9 g / cm 3 or less, i.e., C103 or less, which results in a lightweight part that does not require as much creep strength when used in rotating applications. This is achieved when: A Re +0.67A Ta ≦22 atomic%

[0117] This includes A Re and A Ta However, the densities must be less than 22.0 and 32.8, respectively. The most preferred maximum alloy density is 8 g / cm 3 Below, CMSX-4 and below correspond to the following equation: A Re +0.67A Ta ≦15 atomic%

[0118] This includes A Re and A Ta However, they must be below 15.0 and 22.4 respectively.

[0119] Of the elements within the design space of the present invention, aluminum, zirconium, silicon, hafnium, and titanium are the only components with elemental VECs below the target value (5.0) for the alloy. As shown in Figure 6, minimum amounts of these elements are required to meet the VEC target (5.0 or less) and the entropy target. With the design space restricted in this way, the requirements for these low VEC elements are as follows: A Al +A Zr +A Si +A Hf +A Ti ≧16.5 atomic%

[0120] In one embodiment, it is preferred to increase the levels of aluminum, zirconium, silicon, hafnium, and titanium to even higher levels than those listed above to further reduce the VEC and further increase ductility. For example, to achieve a VEC of 4.6 or less, the following conditions are required: A Al +A Zr +A Si +A Hf +A Ti ≧31.5 atomic%

[0121] The alloys of the present invention are designed to have good ductility as well as good mechanical strength and creep resistance at high temperatures. Since strength is a function of both entropy (as discussed above) and melting point, the melting point must be maximized. Furthermore, creep rates are most severe above a homologous temperature of 0.6. The homologous temperature is defined as follows:

number

[0122] where T is the ambient temperature, T m is the melting point. To lower the homologous temperature and reduce the creep rate, T m can be maximized. This can be achieved by maximizing the melting point index (discussed above). A preferred target minimum melting point index is 2200K, or even 2400K, or even 2500K and 2600K, with these being more preferred limits. Alloys with melting point indices of 2700K or higher, or even 2800K (or 2900K) or higher, are also possible and are preferred in one embodiment. These correspond to the minimum amount of refractory elements in the alloy, and are defined in terms of W equivalents, with reference to Figure 7. Where A W , A Ta , A Mo , A Nb and A Re are the atomic percent concentrations of tungsten, tantalum, molybdenum, niobium, and rhenium in the alloy. W eq = A W +A Ta +A Mo +A Nb +A Re

[0123] For melting point indexes above 2200K, 2400K, 2500K, 2600K, and 2800K, eqshould be greater than approximately 15, 25, 25, 35, and 50, respectively, and should comply with the following formula (derived from Figures 7a-e): More precisely, the melting point index should be greater than the following values: 2200K, W eq ≧ 15 2400K, W eq ≧ 25 2500K, W eq ≧0.6A Al +25 2600K, W eq ≧1.2A Al +30 2800K, W eq ≧0.8A Al +47

[0124] As shown in Figure 8, there is also a trade-off between melting point and density. As the lower melting point limit increases, the minimum achievable density also increases. Similarly, as the upper density limit decreases, the maximum achievable melting point also decreases. Balancing these properties is part of the invention, because higher densities cause higher stresses during rotation, while lowering density reduces the melting point, decreases strength and creep resistance, and decreases the alloy's ability to withstand loads.

[0125] The present invention does not include cost constraints (i.e., element selection is made independently of cost). Cost varies with demand and element availability. Many high-value applications benefit from the high-temperature performance of some of the high-value elements in the design space, such as platinum group metals. These applications have large budgets and low quantities, so the allowable alloy cost is unlimited. In some applications, such as glass fiber manufacturing, the alloys included in the present invention will compete with other alloys with high PGM content. For these, it is preferable to limit the cost to less than 1000 USD / mol. As shown in Figures 9a and 9b, the following requirements hold: A Ir <9.0; A Rh <6.0 where AIr and A Rh are the atomic percentages of iridium and rhodium, respectively, in the alloy.

[0126] For high-volume industrial applications such as gas turbines and aerospace, it is desirable for the alloy cost to be competitive with common refractory alloys such as C103 and FS85. The alloys encompassed by this invention have superior performance compared to conventional alloys, so the increased alloy cost is justified. In this embodiment, it is desirable to limit the cost to less than 100 USD / mol. As shown in Figures 9c-f, the following requirements hold: A Pd <1.5; A Pt <1.5; A Re <14.5; A Ru <8.5;

[0127] In this embodiment, iridium and rhodium are limited to 0.5 atomic % or less due to their very high cost.

[0128] In one embodiment, the alloys encompassed by the present invention can perform at or above the performance of typical refractory alloys, but at a lower cost. The present invention is preferably cost-competitive with existing refractory superalloys and nickel-base superalloys. The alloy cost (USD / mol) is desirably less than 14, preferably less than 12, and even more preferably less than 10. Even lower costs than typical commercial alloys are preferred. In this embodiment, the alloy cost is preferably less than 8, which corresponds to a lower cost than FS85, C103, and CMSX-4, and preferably has an element cost of less than 6.5, and even more preferably less than 5. In the compositional range where the cost is comparable to commercial high-temperature alloys, vanadium and tantalum account for the majority of the total alloy cost.

[0129] A V and A Ta are the atomic percentages of vanadium and tantalum in the alloy, respectively. As shown in Figures 10a-e, if the cost index is less than: 14. ATa <= 20 12. A V +2A Ta <= 40 In this case, A Ta must be 20 or less. 10. A V +A Ta <= 20 8. A V +A Ta <= 15 In this case, A Ta % or less, but if Ta is present at 16.0 atomic % or less, a relatively low-cost alloy can be obtained. 6.5, A V +2A Ta <= 20 In this case, A Ta must be 10 or less.

[0130] In this lowest cost embodiment, iridium and rhodium are permitted only in amounts of 0.1 atomic % or less, palladium and platinum are permitted in amounts of 0.5 atomic % or less, and rhenium and ruthenium are permitted in amounts of 1.0 atomic % or less.

[0131] Aluminum has the lowest VEC and density of any element in the design domain. Due to its large atomic radius, even small additions significantly increase the solid solution strength (Lin et al., 2015). For these reasons, lower limits of 1.0 at.%, 4.0 at.%, or even 7.0 at.% or 10.0 at.% are preferred.

[0132] While increasing the zirconium content can lead to the formation of zirconium-based intermetallic compounds, the addition of zirconium also has the advantage of lowering the valence electron concentration, increasing ductility, and lowering density. For these reasons, increasing the zirconium content to 2.0 atomic percent or more, and even 4.0 atomic percent or more, is preferred. Higher levels provide further improvements, with levels of 6 atomic percent or more, and even 8.0 or 10.0 atomic percent or more, being most preferred when high ductility and low density are desired. Higher zirconium contents, such as 12.0 atomic percent or more, or even 13.0 atomic percent or more, result in alloys with excellent ductility and low density.

[0133] The addition of vanadium, due to its moderate valence electron concentration (see above), low density, and high melting point, is beneficial in increasing configurational entropy without adversely affecting other figures of merit. Low concentrations of vanadium provide a unique combination of high melting point and low density, simultaneously improving high-temperature strength and reducing rotational load, respectively. For these reasons, increasing the vanadium content is desirable. Therefore, vanadium levels of 2.0 atomic percent or greater, preferably 5.0 atomic percent or greater, and even 8.0 atomic percent or greater, are preferred.

[0134] Because tungsten has a high density, it is reasonable to reduce its content to 30.0 atomic % or less, preferably 25.0 atomic % or less, more preferably 20.0 atomic % or less, and even more preferably 15.0 atomic % or less. In one embodiment, to maintain a low density, tungsten is present in an amount of 10.0 atomic % or less. However, because tungsten has the highest melting point of the elements of the present invention, increasing its content may improve temperature and strength capabilities. Therefore, a preferred lower limit for the tungsten content is 2.0 atomic %, further 5.0 atomic %, or even 8.0 atomic %. A tungsten content of 11.0 atomic % or more provides excellent high-temperature strength and is therefore preferred when this property is required.

[0135] Hafnium is beneficial in small amounts because it has the ability to scavenge oxygen and lower the ductile-to-brittle transition temperature, and therefore the preferred lower limit of the hafnium content is 1.0 atomic % or more, preferably 3.0 atomic % or more, and more preferably 5.0 atomic % or more.

[0136] Iron has a moderate effect on properties such as melting point, but does not significantly improve or degrade performance. Increasing iron reduces density, and gradually adding more elements can increase the entropy of the alloy and stabilize the microstructure. This also improves printability by laser powder bed fusion, especially when combined with chromium. For these reasons, increasing the iron level to above 0.5 atomic percent, or even above 2 atomic percent, or even above 4.0 atomic percent, is preferred.

[0137] Nickel has a moderate melting point and density, so small additions can help increase the entropy of the alloy without significantly adversely affecting other properties, and it is therefore preferred to increase the nickel level to 0.5 atomic percent or greater, or even 2.0 atomic percent or greater, or even 4.0 atomic percent or greater.

[0138] The addition of titanium to the alloy has a significant effect on reducing density. For this reason, increasing the titanium level to 5.0 atomic percent or greater is preferred. Higher amounts of titanium may be beneficial in certain applications. In some embodiments, the alloy includes 8.0 atomic percent or greater titanium, or even 13.0 atomic percent or greater, or even 20.0 atomic percent or greater titanium. Titanium contents of 30.0 atomic percent or greater provide alloys with superior density. Titanium can form a variety of intermetallic compounds, including Fe2Ti, as discussed above. Because titanium offers significant benefits to alloy properties due to its low VEC, low density, and moderate melting point, it is preferable to limit other elements (e.g., Fe) instead to control intermetallic compounds. However, reducing the titanium content allows for greater control of the microstructure. For this reason, in some embodiments of the present invention, it is preferred to limit titanium to 34.0 atomic percent or less, more preferably 33.0 atomic percent or less, and even more preferably 32.0 atomic percent or less. In some circumstances, when other elements that form intermetallic compounds with titanium are present in significant amounts, a limit of 25.0 atomic percent or less is preferred.

[0139] Tantalum is expensive because it is difficult to source the metal from conflict-free regions. Additionally, its high density means that a reduced level of tantalum is preferred in the present invention. Tantalum significantly improves high-temperature strength due to its melting point. Therefore, higher levels, such as 2.0 atomic % or more, preferably 5.0 atomic % or more, or even 8.0 atomic % or more or 10.0 atomic % or more, are preferred. When high strength is required, levels of 14.0 atomic % or more, 15.0 atomic % or more, or even 20.0 atomic % or more are preferred.

[0140] The addition of niobium increases the melting point and improves high-temperature strength. While this effect is not as strong as that of other elements such as tungsten, it can be beneficial for some alloy processing methods, such as arc melting, where elements with extremely high melting points are difficult to incorporate into the alloy melt. Therefore, in some embodiments, niobium is present in an amount of 5.0 atomic % or more, or 8.0 atomic % or more, and most preferably 10.0 atomic % or more. Niobium is preferably one of the required elements and therefore present in an amount of 12.0 atomic % or more, or 18.0 atomic % or more. As explained above, niobium can form intermetallic compounds with chromium. While it is preferable to limit chromium to control intermetallic compound formation, in some embodiments, it may be beneficial to reduce niobium. In these cases, the niobium content is 30.0 atomic % or less, preferably 26.0 atomic % or less, or 25.0 atomic % or less, preferably 24.0 atomic % or less, and more preferably 20.0 atomic % or less.

[0141] The addition of molybdenum has the advantage of increasing the melting point and improving the high-temperature strength of the alloy. For this reason, increasing the molybdenum level, for example, to 2.0 atomic percent or greater, can be beneficial. In some embodiments, molybdenum is present in an amount of 4.0 atomic percent or greater, or even 6.0 atomic percent or greater. Molybdenum is preferably an essential element and, therefore, is present in an amount of 8.0 atomic percent or greater, or 10.0 atomic percent or greater, and most preferably, 12.0 atomic percent or greater. At higher amounts, molybdenum forms the volatile oxide species MoO3 upon oxidation. In the case of minor defects in the coating system, volatilization of MoO3 due to scratches or chips can be catastrophic, causing coating spalling and significantly reducing the effective strength of the composition. For this reason, the molybdenum content is preferably 20.0 atomic percent or less, or even 16.0 atomic percent or less, or even 15.0 atomic percent or less. Even more preferably, molybdenum is present in an amount less than or equal to 14.0 atomic percent, or even less than or equal to 12.0 atomic percent, or even less than or equal to 7.0 atomic percent.

[0142] Cobalt has a moderate effect on density, cost, and melting point. Small additions increase entropy and stabilize the microstructure. For these reasons, it can be beneficial to increase the cobalt content, for example, to 0.5 atomic percent or more. In some embodiments, to take advantage of these effects, cobalt is present in an amount of 1.0 atomic percent or more. More preferably, cobalt is present in an amount of 2.0 atomic percent or more, or even 3.0 atomic percent or more. Most preferably, cobalt is present in an amount of 4.0 atomic percent or more.

[0143] Chromium also improves printability during laser powder bed fusion additive manufacturing due to its relatively low density, especially when added in combination with iron. For these reasons, it is preferred to increase the chromium level to 0.5 atomic percent or higher, or even 2.0 atomic percent or higher, or even 4.0 atomic percent or higher.

[0144] Small amounts of copper can increase entropy and stabilize the microstructure. For these reasons, increasing the copper content, for example to 0.5 atomic percent or more, can be beneficial. In some embodiments, to take advantage of these effects, copper is present in an amount of 1.0 atomic percent or more. Even more preferably, copper is present in an amount of 2.0 atomic percent or more, or even 3.0 atomic percent or more.

[0145] Because manganese has a relatively low density, its addition increases entropy and stabilizes the microstructure. For these reasons, it is preferable to increase the manganese content to 0.5 atomic % or more, or 2.0 atomic % or more, or even 4.0 atomic % or more. Furthermore, because manganese has a moderately high VEC, the amount of manganese must be limited in other embodiments of the invention where very low VEC values ​​are required or where large amounts of low-VEC elements cannot be tolerated. Therefore, manganese is preferably present in an amount of 30.0 atomic % or less, more preferably 23.0 atomic % or less, and even more preferably 15.0 atomic % or less. Preferably, to maintain a low VEC, manganese is present in an amount of 1.0 atomic % or less.

[0146] Small additions of silicon can significantly improve strength, provided high silicide fractions are avoided. In this embodiment, silicon levels of 1.0 atomic % or greater are preferred, more preferably 2.0 atomic % or greater, and even more preferably 3.0 atomic % or greater.

[0147] Iridium, like niobium, has the highest melting point of any PGM, but its strong non-reactivity reduces the likelihood of attacking the alloy if the coating is damaged. Therefore, the iridium content is preferably 2.0 atomic % or more, and more preferably 5.0 atomic % or more. In cost-free embodiments, the iridium content is preferably 12.0 atomic % or more, or even 17.0 atomic % or more.

[0148] Ruthenium has a very high melting point, almost the same as iridium, but a significantly lower density and lower cost, and therefore the ruthenium content is 4.0 atomic % or more, preferably 11.0 atomic % or more, more preferably 18.0 atomic % or more, and even more preferably 22.0 atomic % or more.

[0149] Rhodium has a unique combination of high melting point, excellent corrosion resistance, and reasonably low density, making it a suitable addition to alloys, preferably at 5.0 atomic % or more, more preferably at 10.0 atomic % or more, and even more preferably at 15.0 atomic % or more.

[0150] Palladium is an element that can increase entropy by adding small amounts without significantly impairing other properties. This is due to its moderate melting point and relatively low density. Therefore, the palladium content is 2.0 atomic % or more, preferably 5.0 atomic % or more, and more preferably 8.0 atomic % or more.

[0151] Platinum is effective in small amounts due to its corrosion resistance and good compatibility with PGM diffusion barriers (e.g., pure platinum). For these reasons, a content of 3.0 atomic % or more is preferred, with 7.0 atomic % or more being more preferred, and 12.0 atomic % or more being even more preferred.

[0152] Rhenium has the second highest melting point in this region, and small additions can improve high-temperature strength and creep resistance. It thus performs a similar function to tungsten, but replaces the existing tungsten content in the alloy, achieving higher entropy. Therefore, rhenium is preferably present in an amount of 3.0 atomic percent or more, more preferably 8.0 atomic percent or more, and even more preferably 15.0 atomic percent or more. In embodiments where cost is not an issue, rhenium content of 20.0 or 25.0 atomic percent or more may be preferred.

[0153] The alloy may contain unavoidable impurities, but their amount should be limited to a total of 1.0 atomic % to reduce the likelihood of excessive intermetallic compound formation. In particular, in one embodiment, the amount of carbon should be 1.0 atomic % or less, which should be readily achievable using conventional manufacturing techniques. In this manner, the alloy is substantially free of refractory metal carbides. In one embodiment, the alloy is substantially free of carbon.

[0154] Overview of ingredient restrictions [Table 10]

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Claims

1. In atomic percent, Aluminum: 19.45% or less, Zirconium: 16.7% or less, Vanadium: 12.0% or less, Tungsten: 35.0% or less, Chromium: 15.0% or less, Iron: 6.5% or less, Nickel: 15.0% or less, Titanium: 40.0% or less, Tantalum: 35.0% or less, Niobium: 35.0% or less, Molybdenum: 35.0% or less, Cobalt: 20.0% or less, Manganese: 35.0% or less, Copper: 15.0% or less, Hafnium: 10.0% or less, Rhenium: 35.0% or less, Platinum: 15.0% or less, Palladium: 15.0% or less, Rhodium: 20.0% or less, Ruthenium: 25.0% or less, Iridium: 20.0% or less, Silicon: 5.0% or less Including, The total amount of unavoidable impurities is 1 atomic % or less, [Equation 1] where x i is the atomic fraction of element i in the alloy, and VEC i is the number of valence electrons associated with an atom of element i, and R is the universal gas constant.

2. Satisfy the following formula: [Equation 2] where x i is the atomic fraction of element i in the alloy, and ρ i 10. The alloy of claim 1, wherein i is the density of pure element i.

3. Satisfy the following formula: [Equation 3] where x i is the atomic fraction of element i in the alloy bulk composition, and T mi 3. The alloy of claim 1 or 2, wherein i is the melting point of pure element i.

4. Satisfy the following formula: [Equation 4] where x i 4. The alloy of claim 1, wherein i is the atomic fraction of element i in the alloy bulk composition.

5. The alloy contains less than 35% rhenium, Re ≦(35- A Ta )+(35-A W )+(20-A Nb ), where A Re , A Ta , A W and A Nb 5. The alloy of claim 1, wherein rhenium, tantalum, tungsten, and niobium are present in atomic percent amounts, respectively.

6. 6. An alloy according to any one of claims 1 to 5 containing up to 19.0 atomic % aluminum, preferably up to 15.0 atomic % aluminum, more preferably up to 10.0 atomic % aluminum, even more preferably up to 5.0 atomic % aluminum, and most preferably up to 1.0 atomic % aluminum.

7. 7. An alloy according to any one of claims 1 to 6 containing up to 16.0 at.% zirconium, preferably up to 15.0 at.% zirconium, most preferably up to 14.0 at.% zirconium, preferably up to 13.0 at.% zirconium, more preferably up to 12.4 at.% zirconium, and most preferably up to 5.0 at.% zirconium.

8. Satisfy the following formula: 15≦A W +A Ta +A Mo +A Nb +A Re Preferably, 25≦A W +A Ta +A Mo +A Nb +A Re More preferably, 0.6A Al +25≦A W +A Ta +A Mo +A Nb +A Re Even more preferably, 1.2A Al +30≦A W +A Ta +A Mo +A Nb +A Re Most preferably, 0.8A Al +47≦A W +A Ta +A Mo +A Nb +A Re where A W , A Al , A Ta , A Mo , A Re , A Nb 8. The alloy of claim 1, wherein tungsten, aluminum, tantalum, molybdenum, rhenium, and niobium are the atomic percentages of tungsten, aluminum, tantalum, molybdenum, rhenium, and niobium, respectively, in the alloy.

9. 9. An alloy according to any one of claims 1 to 8 containing up to 10.0 atomic % vanadium, preferably up to 7.3 atomic % vanadium, more preferably up to 4.3 atomic % vanadium, and most preferably up to 1.0 atomic % vanadium.

10. 10. An alloy according to any one of claims 1 to 9 containing up to 10.0 atomic % palladium, preferably up to 5.0 atomic % palladium, more preferably up to 1.5 atomic % palladium, even more preferably up to 1.0 atomic % palladium, and most preferably up to 0.5 atomic % palladium.

11. 11. An alloy according to any one of claims 1 to 10 comprising up to 15.0 atomic % Iridium, preferably up to 9.0 atomic % Iridium, preferably up to 8.0 atomic % Iridium, more preferably up to 1.0 atomic % Iridium, preferably up to 0.5 atomic % Iridium, more preferably up to 0.1 atomic % Iridium.

12. 12. An alloy according to any one of claims 1 to 11 containing up to 15.0 atomic % rhodium, preferably up to 8.0 atomic % rhodium, more preferably up to 6.0 atomic % rhodium, more preferably up to 1.0 atomic % rhodium, even more preferably up to 0.5 atomic % rhodium, and most preferably up to 0.1 atomic % rhodium.

13. 13. An alloy according to any one of claims 1 to 12 comprising at least 2.0 atomic % iridium, preferably at least 5.0 atomic % iridium, more preferably at least 12.0 atomic % iridium, and even more preferably at least 17.0 atomic % iridium.

14. 14. An alloy according to any one of claims 1 to 13 comprising at least 5.0 atomic % rhodium, preferably at least 10.0 atomic % rhodium, and more preferably at least 15.0 atomic % rhodium.

15. 15. An alloy according to any one of claims 1 to 14 comprising at least 2.0 atomic % palladium, preferably at least 5.0 atomic % palladium, more preferably at least 8.0 atomic % palladium.

16. 16. An alloy according to any one of claims 1 to 15, comprising at least 3.0 atomic % platinum, preferably at least 7.0 atomic % platinum, and more preferably at least 12.0 atomic % platinum.

17. 17. An alloy according to any one of claims 1 to 16 comprising up to 10.0 atomic % platinum, preferably up to 5.0 atomic % platinum, more preferably up to 1.5 atomic % platinum, even more preferably up to 1.0 atomic % platinum, and even more preferably up to 0.5 atomic % platinum.

18. 18. An alloy according to any one of claims 1 to 17 comprising up to 34.0 atomic % tungsten, preferably up to 30.0 atomic % tungsten, more preferably up to 29.0 atomic % tungsten, even more preferably up to 25.0 atomic % tungsten, even more preferably up to 20.0 atomic % tungsten, even more preferably up to 15.0 atomic % tungsten, and most preferably up to 10.0 atomic % tungsten.

19. 19. An alloy according to any one of the preceding claims containing at least 2.0 atomic % vanadium, preferably at least 5.0 atomic % vanadium, preferably at least 8.0 atomic % vanadium.

20. 20. An alloy according to any one of the preceding claims comprising at least 2.0 atomic % tungsten, preferably at least 5.0 atomic % tungsten, preferably at least 8.0 atomic % tungsten, more preferably at least 11.0 atomic % tungsten.

21. 21. An alloy according to any one of claims 1 to 20 containing up to 6.5 atomic % iron, preferably up to 3.0 atomic % iron, most preferably up to 1.0 atomic % iron.

22. 22. An alloy according to any one of the preceding claims containing up to 3.0 atomic % silicon, preferably up to 1.0 atomic % silicon, more preferably 0 atomic % silicon.

23. 23. An alloy according to any one of claims 1 to 22 comprising at least 1.0 atomic % silicon, preferably at least 2.0 atomic % silicon, more preferably at least 3.0 atomic % silicon.

24. 24. An alloy according to any one of claims 1 to 23 containing up to 8.0 atomic % nickel, preferably up to 3.0 atomic % nickel, more preferably up to 1.0 atomic % nickel.

25. 25. An alloy according to any one of claims 1 to 24 containing up to 14.0 atomic % chromium, preferably up to 13.0 atomic % chromium, more preferably up to 7.7 atomic % chromium, even more preferably up to 7.0 atomic % chromium, and most preferably up to 2.0 atomic % chromium. or 26. An alloy according to any one of claims 1 to 25 containing up to 15.0 atomic % rhodium, preferably up to 8.0 atomic % rhodium, more preferably up to 1.0 atomic % rhodium.

26. 26. An alloy according to any one of claims 1 to 25 containing up to 35.0 atomic % titanium, preferably up to 34.0 atomic % titanium, more preferably up to 33.0 atomic % titanium, even more preferably up to 32.0 atomic % titanium, and even more preferably up to 25.0 atomic % titanium.

27. 27. An alloy according to any one of claims 1 to 26 containing at least 5.0 at.% titanium, preferably at least 8.0 at.% titanium, more preferably at least 13.0 at.% titanium, most preferably at least 20.0 at.% titanium, and even more preferably at least 30.0 at.% titanium.

28. 28. An alloy according to any one of claims 1 to 27 comprising up to 32.8 at.% tantalum, preferably up to 29.0 at.% tantalum, more preferably up to 25.0 at.% tantalum, even more preferably up to 22.4 at.% tantalum, even more preferably up to 20.0 at.% tantalum, even more preferably up to 15.0 at.% tantalum, preferably up to 10.0 at.% tantalum.

29. 29. An alloy according to any one of claims 1 to 28 comprising at least 2.0 at.% tantalum, preferably at least 5.0 at.% tantalum, preferably at least 10.0 at.% tantalum, more preferably at least 15.0 at.% tantalum, and most preferably at least 20.0 at.% tantalum.

30. 30. An alloy according to any one of claims 1 to 29 comprising up to 30.0 at.% niobium, preferably up to 25.0 at.% niobium, more preferably up to 20.0 at.% niobium, even more preferably up to 18.0 at.% niobium, even more preferably up to 12.0 at.% niobium, and even more preferably up to 10.0 at.% niobium.

31. 31. An alloy according to any one of claims 1 to 30 comprising at least 4.0 atomic % ruthenium, preferably at least 11.0 atomic % ruthenium, more preferably at least 18.0 atomic % ruthenium, and even more preferably at least 22.0 atomic % ruthenium.

32. 32. An alloy according to any one of claims 1 to 31 comprising up to 18.0 atomic % ruthenium, preferably up to 10.0 atomic % ruthenium, more preferably up to 8.5 atomic % ruthenium, and even more preferably up to 1.0 atomic % ruthenium.

33. 33. An alloy according to any one of the preceding claims containing at least 5.0 at.% niobium, preferably at least 8.0 at.% niobium, more preferably at least 10.0 at.% niobium, preferably at least 12.0 at.% niobium, and most preferably at least 18.0 at.% niobium.

34. 34. An alloy according to any one of claims 1 to 33 comprising up to 20.0 at.% molybdenum, preferably up to 16.0 at.% molybdenum, preferably up to 15.0 at.% molybdenum, preferably up to 14.0 at.% molybdenum, more preferably up to 12.0 at.% molybdenum, and even more preferably up to 7.0 at.% molybdenum.

35. 35. An alloy according to any one of claims 1 to 34 comprising at least 2.0 atomic % molybdenum, preferably at least 4.0 atomic % molybdenum, more preferably at least 6.0 atomic % molybdenum, even more preferably at least 8.0 atomic % molybdenum, even more preferably at least 10.0 atomic % molybdenum, and most preferably at least 12.0 atomic % molybdenum.

36. 36. An alloy according to any one of the preceding claims containing at least 0.5 atomic % nickel, preferably at least 2.0 atomic % nickel, more preferably at least 4.0 atomic % nickel.

37. 37. An alloy according to any one of the preceding claims containing at least 0.5 atomic % iron, preferably at least 2.0 atomic % iron, more preferably at least 4.0 atomic % iron.

38. 38. An alloy according to any one of the preceding claims containing at least 1.0 atomic % hafnium, preferably at least 3.0 atomic % hafnium, more preferably at least 5.0 atomic % hafnium.

39. 39. An alloy according to any one of the preceding claims comprising at least 2.0 atomic % tungsten, preferably at least 5.0 atomic % tungsten, more preferably at least 8.0 atomic % tungsten, and even more preferably at least 11.0 atomic % tungsten.

40. 40. An alloy according to any one of the preceding claims containing at least 1.0 at.% Aluminium, preferably at least 4.0 at.% Aluminium, more preferably at least 7.0 at.% Aluminium, and even more preferably at least 10.0 at.% Aluminium.

41. 41. An alloy according to any one of claims 1 to 40 comprising at least 2.0 atomic % zirconium, preferably at least 4.0 atomic % zirconium, more preferably at least 6.0 atomic % zirconium, even more preferably at least 8.0 atomic % zirconium, even more preferably at least 10.0 atomic % zirconium, and most preferably at least 12.0 atomic % zirconium.

42. 42. An alloy according to any one of claims 1 to 41 comprising up to 15.0 atomic % cobalt, preferably up to 10.0 atomic % cobalt, more preferably up to 7.0 atomic % cobalt.

43. 43. An alloy according to any one of claims 1 to 42 comprising at least 0.5 atomic % cobalt, preferably at least 1.0 atomic % cobalt, more preferably at least 2.0 atomic % cobalt, even more preferably at least 3.0 atomic % cobalt, and most preferably at least 4.0 atomic % cobalt.

44. 44. An alloy according to any one of the preceding claims containing up to 10.0 atomic % copper, preferably up to 5.0 atomic % copper, more preferably up to 2.0 atomic % copper.

45. 45. An alloy according to any one of the preceding claims containing at least 0.5 at.% copper, preferably at least 1.0 at.% copper, more preferably at least 2.0 at.% copper, and even more preferably at least 3.0 at.% copper.

46. 46. ​​An alloy according to any one of the preceding claims containing at least 0.5 atomic % chromium, preferably at least 2.0 atomic % chromium, and more preferably at least 4.0 atomic % chromium.

47. 47. An alloy according to any one of the preceding claims containing at least 0.5 atomic % manganese, preferably at least 2.0 atomic % manganese, and more preferably at least 4.0 atomic % manganese.

48. 48. An alloy according to any one of claims 1 to 47 containing up to 30.0 at.% manganese, preferably up to 23.0 at.% manganese, more preferably up to 15.0 at.% manganese, and most preferably up to 1.0 at.% manganese.

49. 49. An alloy according to any one of claims 1 to 48 comprising at least 3.0 atomic % rhenium, preferably at least 5.0 atomic % rhenium, more preferably at least 8.0 atomic % rhenium, even more preferably at least 15.0 atomic % rhenium, even more preferably at least 20.0 atomic % rhenium, and most preferably at least 25.0 atomic % rhenium.

50. 50. An alloy according to any one of claims 1 to 49 containing up to 28.0 atomic % rhenium, preferably up to 22.0 atomic % rhenium, more preferably up to 20.0 atomic % rhenium, more preferably up to 15.0 atomic % rhenium, more preferably up to 14.5 atomic % rhenium, more preferably up to 10.0 atomic % rhenium, more preferably up to 5.0 atomic % rhenium, more preferably up to 1.0 atomic % rhenium.

51. 51. An alloy according to any one of the preceding claims containing up to 5.5 atomic % hafnium, preferably up to 1.0 atomic % hafnium.

52. 52. The alloy of any one of claims 1 to 51, satisfying the following formula: [Equation 5]

53. Satisfy the following formula: A W +0.8A Ta ≦43 Preferably, A W +0.8A Ta ≦34 More preferably, A W +0.8A Ta ≦29 Most preferably, A W +0.8A Ta ≦20 where A Ta and A W 53. The alloy of any one of claims 1 to 52, wherein Λ and Λ are the atomic percentages of tantalum and tungsten, respectively, in the alloy.

54. Satisfy the following formula: A Re +0.67A Ta ≦35 Preferably, A Re +0.67A Ta ≦28 More preferably, A Re +0.67A Ta ≦22 Most preferably, A Re +0.67A Ta ≦15 where A Re and A Ta 54. The alloy of any one of claims 1 to 53, wherein rhenium and tantalum are the atomic percentage amounts, respectively, of rhenium and tantalum in the alloy.

55. Satisfy the following formula: A Al +A Zr +A Ti +A Si +A Hf ≧16.5 Preferably, A Al +A Zr +A Ti +A Si +A Hf ≧31.5 where A Al , A Zr , A Si , A Hf , A Ti 55. The alloy of any one of claims 1 to 54, wherein x, y, zirconium, silicon, hafnium, and titanium are the atomic percent amounts, respectively, of aluminum, zirconium, silicon, hafnium, and titanium in the alloy.

56. Satisfy the following formula: A V +2A Ta ≦40 Preferably, A V +A Ta ≦20 Preferably, A V +A Ta ≦15 Preferably, A V +2A Ta ≦20 where A V and A Ta 56. The alloy of any one of claims 1 to 55, wherein x, y, and z are the atomic percentage amounts of vanadium and tantalum, respectively, in the alloy.

57. 57. The alloy of any one of claims 1 to 56, wherein the alloy is a single phase alloy.

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