Creep-resistant titanium alloy

Abstract

The present application relates to creep resistant titanium alloys. One non-limiting embodiment of a titanium alloy includes, in weight percent of total alloy weight: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; titanium; and impurities. One non-limiting embodiment of the titanium alloy includes zirconium-silicon-germanium intermetallic precipitates and exhibits a steady state creep rate of less than 8 x 10 ‑4 (24 hours) ‑1 at a temperature of at least 890 °F under a load of 52 ksi.

Description

[0001] This application is a divisional application of the invention patent application filed on June 17, 2019, with application number "201980054572.9" and title "Creep-resistant Titanium Alloy". Technical Field

[0002] This disclosure relates to creep-resistant titanium alloys. Background Technology

[0003] Titanium alloys typically exhibit a high strength-to-weight ratio, corrosion resistance, and creep resistance at moderately high temperatures. For example, the Ti-5Al-4Mo-4Cr-2Sn-2Zr alloy (also known as the "Ti-17 alloy," with its composition specified in UNS R58650) is a commercially available alloy widely used in jet engine applications requiring a combination of high strength, fatigue resistance, and toughness at operating temperatures up to 800℉. Other examples of titanium alloys for high-temperature applications include the Ti-6Al-2Sn-4Zr-2Mo alloy (with its composition specified in UNS R54620) and the Ti-3Al-8V-6Cr-4Mo-4Zr alloy (also known as "β-C," with its composition specified in UNS R58640). However, the creep resistance of these alloys at high temperatures is limited. Therefore, there is a need for titanium alloys with improved creep resistance at high temperatures. Summary of the Invention

[0004] According to a non-limiting aspect of this disclosure, a titanium alloy comprises, by weight percentage of the total alloy weight: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; titanium; and impurities.

[0005] According to another non-limiting aspect of this disclosure, a titanium alloy is substantially composed of the following by weight percentage of the total alloy weight: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; titanium; and impurities.

[0006] According to another non-limiting aspect of this disclosure, a titanium alloy comprises, by weight percentage of the total alloy weight: 2 to 7 aluminum; 0 to 5 tin; 0 to 5 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.05 to 2.0 germanium; 0 to 0.30 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0 to 0.05 carbon; 0 to 0.015 hydrogen; titanium; and impurities. Attached Figure Description

[0007] The features and advantages of the alloys, articles, and methods described herein can be better understood by referring to the accompanying drawings, in which:

[0008] Figure 1 It is a graph showing the creep strain over time of certain non-limiting embodiments of titanium alloys according to this disclosure compared to certain conventional titanium alloys.

[0009] Figure 2 The image includes a micrograph of a non-limiting embodiment of a titanium alloy according to the present disclosure, and a graph showing the results of an energy-dispersive X-ray (XRD) scan of the alloy prior to exposure to sustained load.

[0010] Figure 3 Include Figure 2 Micrographs of the titanium alloy, and graphs showing the XRD results of the alloy and the distribution of Zr / Si / Ge precipitates into the intermetallic matrix after heating the alloy at 900℉ for 125 hours under a continuous load of 52 kSi; and

[0011] Figure 4 It shows Figure 3 Elemental diagram of titanium alloys.

[0012] The foregoing details, as well as other details, will be understood when considering the following detailed description of certain non-limiting embodiments of this disclosure. Detailed Implementation

[0013] In this description of non-limiting embodiments, all figures representing quantities or characteristics should be understood in all cases to be modified by the term "about," except in operational examples or where otherwise indicated. Therefore, unless indicated to the contrary, any numerical parameter set forth in the following description is an approximation and may vary depending on the desired properties sought to be obtained from the material according to this disclosure and by the methods according to this disclosure. At least, and not at all, the application of the doctrine of equivalents is limited to the scope of the claims, each numerical parameter should be interpreted based on at least the reported number of significant figures and by the application of common rounding techniques. Unless otherwise stated, all scopes described herein include the endpoints.

[0014] Any patent, publication, or other disclosure that is allegedly incorporated herein in whole or in part by reference is incorporated herein only to the extent that the incorporated material does not conflict with the existing definitions, statements, or other disclosures set forth in this disclosure. Therefore, and as necessary, the disclosures set forth herein may supersede any conflicting material incorporated herein by reference. Any material, or part thereof, that is allegedly incorporated herein by reference but conflicts with the existing definitions, statements, or other disclosures set forth herein is incorporated only to the extent that the incorporated material does not conflict with the existing disclosures.

[0015] The references herein to titanium alloys “comprising” a particular composition are intended to cover alloys that are “substantially composed of” or “consistent with” the composition. It will be understood that the titanium alloy compositions described herein that “comprising”, “consistent with”, or “substantially composed of” a particular composition may also contain impurities.

[0016] Articles and parts exposed to high temperatures may creep. As used herein, “high temperature” refers to a temperature exceeding approximately 200℉. Creep is the time-varying strain that occurs under stress. Creep occurring at a decreasing strain rate is called primary creep; creep occurring at a minimum and nearly constant strain rate is called second-order (steady-state) creep; and creep occurring at an accelerating strain rate is called third-order creep. Creep strength is the stress that will cause a given creep strain in a creep test conducted at a given time in a specified constant environment.

[0017] The creep resistance of titanium and titanium alloys under high temperatures and sustained loads depends primarily on their microstructure characteristics. Titanium exists in two allotropic forms: the beta (“β”) phase, with a body-centered cubic (“bcc”) crystal structure; and the alpha (“α”) phase, with a hexagonal close-packed (“hcp”) crystal structure. Typically, β titanium alloys exhibit poor high-temperature creep strength. This poor high-temperature creep strength is due to the significant concentration of the β phase present in these alloys at high temperatures (e.g., 900℉). The β phase is not well resistant to creep due to its body-centered cubic structure, which provides numerous deformation mechanisms. These drawbacks have limited the use of β titanium alloys.

[0018] A group of titanium alloys widely used in various applications is α / β titanium alloy. In α / β titanium alloys, the distribution and size of primary α particles directly affect creep resistance. According to various published reports on research on silicon-containing α / β titanium alloys, the precipitation of silicides at grain boundaries can further improve creep resistance, but it will impair room temperature tensile ductility. The reduction in room temperature tensile ductility caused by the addition of silicon limits the concentration of silicon that can be added to typically 0.3% (by weight).

[0019] This disclosure relates in part to alloys that address certain limitations of conventional titanium alloys. One embodiment of a titanium alloy according to this disclosure, by weight percentage of the total alloy weight, comprises (i.e., includes): 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; titanium; and impurities. Another embodiment of a titanium alloy according to this disclosure, by weight percentage of the total alloy weight, comprises: 5.5 to 6.5 aluminum; 1.7 to 2.1 tin; 1.7 to 2.1 molybdenum; 3.4 to 4.4 zirconium; 0.03 to 0.11 silicon; 0.1 to 0.4 germanium; titanium; and impurities. In another embodiment of the titanium alloy according to this disclosure, by weight percentage of the total alloy weight, it comprises: 5.9 to 6.0 aluminum; 1.9 to 2.0 tin; 1.8 to 1.9 molybdenum; 3.7 to 4.0 zirconium; 0.06 to 0.11 silicon; 0.1 to 0.4 germanium; titanium; and impurities. In non-limiting embodiments of the alloy according to this disclosure, concomitant elements and other impurities in the alloy composition may include one or more of, or substantially consist of, the following: oxygen, iron, nitrogen, carbon, hydrogen, niobium, tungsten, vanadium, tantalum, manganese, nickel, hafnium, gallium, antimony, cobalt, and copper. Certain non-limiting embodiments of the titanium alloy according to this disclosure may include, by weight percentage of the total alloy weight: 0.01 to 0.25 oxygen; 0 to 0.30 iron; 0.001 to 0.05 nitrogen; 0.001 to 0.05 carbon; 0 to 0.015 hydrogen; and 0 to 0.1 each of niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper.

[0020] Aluminum may be included in the alloys according to this disclosure to increase the α content and provide increased strength. In some non-limiting embodiments according to this disclosure, the amount of aluminum present may be 2-7% by weight of the total alloy weight. In some non-limiting embodiments, the amount of aluminum present may be 5.5-6.5% by weight of the total alloy weight, or in some embodiments, 5.9-6.0%.

[0021] Tin may be included in the alloy according to this disclosure to increase the α content and provide increased strength. In some non-limiting embodiments according to this disclosure, the amount of tin present may be 0-4% by weight of the total alloy weight. In some non-limiting embodiments, the amount of tin present may be 1.5-2.5% by weight of the total alloy weight, or in some embodiments, 1.7-2.1%.

[0022] Molybdenum may be included in the alloys according to this disclosure to increase the β content and provide increased strength. In some non-limiting embodiments according to this disclosure, the amount of molybdenum present may be 0-5% by weight of the total alloy weight. In some non-limiting embodiments, the amount of molybdenum present may be 1.3-2.3% by weight of the total alloy weight, or in some embodiments, 1.7-2.1%.

[0023] Zirconium may be included in alloys according to this disclosure to increase the α content, providing increased strength and increased creep resistance by forming intermetallic precipitates. In some non-limiting embodiments according to this disclosure, the amount of zirconium present may be 1-10% by weight of the total alloy weight. In some non-limiting embodiments, the amount of zirconium present may be 3.4-4.4% by weight of the total alloy weight, or in some embodiments, 3.5-4.3%.

[0024] Silicon may be included in the alloys according to this disclosure to provide increased creep resistance by forming intermetallic precipitates. In some non-limiting embodiments according to this disclosure, the amount of silicon present may be 0.01-0.30% by weight of the total alloy weight. In some non-limiting embodiments, the amount of silicon present may be 0.03-0.11% by weight of the total alloy weight, or in some embodiments, 0.06-0.11%.

[0025] Germanium may be included in embodiments of the titanium alloys according to this disclosure to improve secondary creep rate performance at high temperatures. In some non-limiting embodiments according to this disclosure, the amount of germanium present may be 0.05-2.0% by weight of the total alloy weight. In some non-limiting embodiments, the amount of germanium present may be 0.1-2.0% by weight of the total alloy weight, or in some embodiments, 0.1-0.4%. Without being bound by any theory, it is believed that the germanium content of the alloy, combined with suitable heat treatment, can promote the precipitation of zirconium-silicon-germanium intermetallic precipitates. The addition of germanium may be, for example, by pure metal or by intermediate alloys of germanium and one or more other suitable metallic elements. Si-Ge and Al-Ge may be suitable examples of intermediate alloys. Some intermediate alloys may be in the form of powder, pellets, wires, chips, or flakes. The titanium alloys described herein are not limited in this respect. After final melting to obtain a substantially homogeneous mixture of titanium and alloying elements, the ingot can be thermomechanically processed through one or more of the following steps to obtain the desired microstructure: forging, rolling, extrusion, drawing, die forging, upsetting, and annealing. It should be understood that the alloys of this disclosure can be thermomechanically processed and / or treated by other suitable methods.

[0026] A non-limiting embodiment of the method for manufacturing titanium alloys according to this disclosure includes annealing heat treatment, solution treatment and annealing, solution treatment and aging (STA), direct aging, or a combination of thermal cycling to achieve a desired balance of mechanical properties. As used herein, a “solution treatment and aging (STA)” process refers to a heat treatment process applied to a titanium alloy that involves solution treatment of the titanium alloy at a solution treatment temperature below the β transformation temperature of the titanium alloy. In one non-limiting embodiment, the solution treatment temperature is in the temperature range of about 1780℉ to about 1800℉. Subsequently, the solution-treated alloy is aged by heating the alloy for a period of time to an aging temperature range below the β transformation temperature and below the solution treatment temperature of the titanium alloy. As used herein, terms such as “heated to” or “heating to” relative to a temperature, temperature range, or minimum temperature mean that the alloy is heated until the temperature of at least a desired portion of the alloy is at least equal to a reference temperature or minimum temperature over the entire range of said portion, or within a reference temperature range. In one non-limiting embodiment, the solution treatment time is in the range of about 30 minutes to about 4 hours. It is generally accepted that, in some non-limiting embodiments, the solution treatment time can be less than 30 minutes or longer than 4 hours, and typically depends on the size and cross-section of the titanium alloy. After the solution treatment is completed, the titanium alloy is cooled to ambient temperature at a rate depending on the cross-sectional thickness of the titanium alloy.

[0027] The solution-treated titanium alloy is then aged at an aging temperature (also referred to herein as the "aging hardening temperature"), i.e., in an α+β two-phase field below the β transformation temperature of the titanium alloy. In one non-limiting embodiment, the aging temperature is in the range of about 1075℉ to about 1125℉. In some non-limiting embodiments, the aging time can range from about 30 minutes to about 8 hours. It is acknowledged that in some non-limiting embodiments, the aging time can be shorter than 30 minutes or longer than 8 hours, and generally depends on the size and cross-section of the titanium alloy product. The general techniques used in the STA processing of titanium alloys are known to those skilled in the art and are therefore not discussed further herein.

[0028] Although it is recognized that the mechanical properties of titanium alloys are generally affected by the size of the tested sample, in certain non-limiting embodiments of the titanium alloys according to this disclosure, the titanium alloys exhibit less than 8 x 10⁻⁶ at a temperature of at least 890℉ and a load of 52 ksi. -4 (24 hours) -1 The steady-state (also referred to as second-order or "Phase II") creep rate. Moreover, for example, certain non-limiting embodiments of the titanium alloys according to this disclosure can exhibit a creep rate of less than 8 x 10⁻⁶ at a temperature of 900℉ and a load of 52 ksi. -4 (24 hours) -1The steady-state (second-order or "Phase II") creep rate. In some non-limiting embodiments according to this disclosure, the titanium alloy exhibits an ultimate tensile strength of at least 130 ksi at 900℉. In other non-limiting embodiments, the titanium alloy according to this disclosure reaches 0.1% creep strain in a time of not less than 20 hours under a load of 52 ksi at 900℉.

[0029] The following examples are intended to further describe non-limiting embodiments according to this disclosure, without limiting the scope of the invention. Those skilled in the art will understand that variations of the following examples may also fall within the scope of the invention, which is defined only by the claims.

[0030] Example 1

[0031] Table 1 lists the elemental compositions of certain non-limiting embodiments of titanium alloys according to this disclosure (“Experimental Titanium Alloy 1”, “Experimental Titanium Alloy 2” and “Experimental Titanium Alloy 3”) and comparative titanium alloys (“Comparative Titanium Alloys”) that do not contain intentionally added germanium.

[0032] Table 1

[0033]

[0034]

[0035] Plasma arc furnaces were used to generate plasma arc melting (PAM) heat for the comparative titanium alloys, experimental titanium alloy 1, experimental titanium alloy 2, and experimental titanium alloy 3 listed in Table 1 to produce 9-inch diameter electrodes, each weighing approximately 400–800 pounds. The electrodes were remelted in a vacuum arc remelting (VAR) furnace to produce 10-inch diameter ingots. Each ingot was transformed into a 3-inch diameter billet using a hot press. After a β-forging step to a 7-inch diameter, an α+β pre-strain forging step to a 5-inch diameter, and a β-final forging step to a 3-inch diameter, the ends of each billet were cut off to remove shrinkage and end cracks, and the billets were cut into multiple pieces. Samples were taken from the top and bottom of each billet (7 inches in diameter) for chemical analysis and β-transformation. Based on the chemical analysis results of the intermediate billets, 2-inch samples were cut from the billets and forged into a “pancake” shape on a press. The pancake-shaped samples were heat-treated to the following solution treatment and aging conditions: the titanium alloy was solution treated at 1780℉ to 1800℉ for 4 hours; the titanium alloy was cooled to ambient temperature at a rate depending on the cross-sectional thickness of the titanium alloy; the titanium alloy was aged at 1025℉ to 1125℉ for 8 hours; and the titanium alloy was air-cooled.

[0036] Test blanks for room temperature and high temperature tensile testing, creep testing, fracture toughness, and microstructure analysis were cut from the STA-processed pancake-shaped samples. Following testing, a final chemical analysis was performed on the fracture toughness specimens to ensure an accurate correlation between chemical and mechanical properties. Certain mechanical properties of the experimental titanium alloys listed in Table 1 were measured and compared with those of the comparative titanium alloys listed in Table 1. The results are presented in Table 2. Tensile testing was performed according to ASTM Standard E8 / E8M-09 (“Standard Test Methods for Tension Testing of Metallic Materials”, ASTM International, 2009). As shown in the results presented in Table 2, the experimental titanium alloy samples exhibited room temperature ultimate tensile strength and yield strength comparable to the comparative titanium alloys (which did not contain intentionally added germanium).

[0037] Table 2

[0038]

[0039] Heat treatment:

[0040] 1- Solution treatment at 17854℉ for 4 hours, water quenching, aging at 1100℉ for 8 hours, and air cooling.

[0041] 2- Solution treatment at 1800℉ for 4 hours, water quenching, aging at 1100℉ for 8 hours, and air cooling.

[0042] Creep-fracture tests were performed on the alloys listed in Table 1 according to ASTM E139. The results are presented in... Figure 1 In comparison, the experimental titanium alloys of this disclosure exhibit a highly favorable second-order creep rate. (Reference) Figure 2-4 After creep exposure to sustained loads and high temperatures exceeding the primary (or Phase I) creep time, zirconium-silicon-germanium intermetallic phase precipitation was detected in experimental titanium alloy No. 2. Figure 1 As shown, the experimental titanium alloy samples of this disclosure exhibited steady-state creep after approximately 30 hours under a load of 52 ksi at 900℉. The comparative titanium alloy reached 0.1% creep strain in 19.4 hours under a load of 52 ksi at 900℉. Experimental titanium alloys 1, 2, and 3 all reached 0.1% creep strain in significantly longer times under a load of 52 ksi at 900℉: 32.6 hours, 55.3 hours, and 93.3 hours, respectively.

[0043] No intermetallic deposits were observed in samples examined prior to creep exposure (but after heat treatment). Reference Figure 2Elemental scanning of experimental titanium alloy No. 2 prior to creep exposure using energy-dispersive X-rays (EDS) revealed that germanium was substantially uniformly distributed in the α / β microstructure without intermetallic particles. Figure 3-4 In the study, following creep exposure, the partitioning of zirconium, silicon, and germanium into intermetallic particles is visible. These intermetallic particles typically indicate aluminum depletion relative to the surrounding α-particles. The precipitation of intermetallic particles after creep exposure is particularly unexpected and surprising. Without intending to be bound by any theory, it is believed that intermetallic particles can improve the secondary creep of the alloy without significantly affecting its high-temperature yield strength.

[0044] The alloys according to this disclosure have a variety of potential applications. As described and demonstrated above, the titanium alloys described herein are advantageously suited for a wide range of applications where creep resistance at high temperatures is important. Particularly advantageous articles made from the titanium alloys according to this disclosure include certain aerospace applications, such as jet engine turbine disks and turbofan blades. Those skilled in the art will be able to manufacture the aforementioned devices, parts, and other articles from the alloys according to this disclosure without further description provided herein. The foregoing examples of possible applications of the alloys according to this disclosure are provided by way of example only and are not exhaustive of all applications in which the forms of products made from this alloy can be applied. Upon reading this disclosure, those skilled in the art can readily identify other applications of the alloys described herein.

[0045] The various non-exhaustive, non-limiting aspects of the novel alloys and methods according to this disclosure may be used alone or in combination with one or more other aspects described herein. Without limiting the foregoing description, in a first non-limiting aspect of this disclosure, a titanium alloy comprises, by weight percentage of the total alloy weight: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; titanium; and impurities.

[0046] According to a second non-limiting aspect of this disclosure that can be used in combination with the first aspect, the titanium alloy comprises, by weight percentage of the total alloy weight: 5.5 to 6.5 aluminum; 1.7 to 2.1 tin; 1.7 to 2.1 molybdenum; 3.4 to 4.4 zirconium; 0.03 to 0.11 silicon; 0.1 to 0.4 germanium; titanium; and impurities.

[0047] According to a third non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the titanium alloy comprises, by weight percentage of the total alloy weight: 5.9 to 6.0 aluminum; 1.9 to 2.0 tin; 1.8 to 1.9 molybdenum; 3.5 to 4.3 zirconium; 0.06 to 0.11 silicon; 0.1 to 0.4 germanium; titanium; and impurities.

[0048] According to a fourth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the titanium alloy further comprises, by weight percentage of the total alloy weight: 0 to 0.30 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0 to 0.05 carbon; 0 to 0.015 hydrogen; and 0 to 0.1 each of niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper.

[0049] According to the fifth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the titanium alloy comprises a zirconium-silicon-germanium intermetallic precipitate.

[0050] According to a sixth non-limiting aspect of this disclosure, which can be used in combination with each or any of the foregoing aspects, the titanium alloy exhibits a strength of less than 8 x 10⁻⁶ kJ / m² at a temperature of at least 890 °F and a load of 52 kJ / m². -4 (24 hours) -1 The steady-state creep rate.

[0051] According to the seventh non-limiting aspect of this disclosure, a method of manufacturing a titanium alloy includes: solution treating the titanium alloy at 1780℉ to 1800℉ for 4 hours; cooling the titanium alloy to ambient temperature at a rate depending on the cross-sectional thickness of the titanium alloy; aging the titanium alloy at 1025℉ to 1125℉ for 8 hours; and air-cooling the titanium alloy, wherein the titanium alloy has the composition described in each or any of the foregoing aspects.

[0052] According to the eighth non-limiting aspect of this disclosure, which can be used in combination with each or any of the foregoing aspects, the titanium alloy exhibits an ultimate tensile strength of at least 130 ksi at 900℉.

[0053] According to the ninth non-limiting aspect of this disclosure, this disclosure also provides a titanium alloy that, by weight percentage of the total alloy weight, is substantially composed of: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; titanium; and impurities.

[0054] According to the tenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the aluminum content in the alloy is 5.9 to 6.0% by weight of the total alloy weight.

[0055] According to the eleventh non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the tin content in the alloy is 1.7 to 2.1% by weight of the total alloy weight.

[0056] According to the twelfth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the tin content in the alloy is 1.9 to 2.0% by weight percentage of the total alloy weight.

[0057] According to the thirteenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the molybdenum content in the alloy is 1.7 to 2.1% by weight of the total alloy weight.

[0058] According to the fourteenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the molybdenum content in the alloy is 1.8 to 1.9% by weight of the total alloy weight.

[0059] According to the fifteenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the zirconium content in the alloy is 3.4 to 4.4% by weight of the total alloy weight.

[0060] According to the sixteenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the zirconium content in the alloy is 3.5 to 4.3% by weight of the total alloy weight.

[0061] According to the seventeenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the silicon content in the alloy is from 0.03 to 0.11% by weight of the total alloy weight.

[0062] According to the eighteenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the silicon content in the alloy is from 0.06 to 0.11% by weight of the total alloy weight.

[0063] According to the nineteenth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the germanium content in the alloy is 0.1 to 0.4% by weight of the total alloy weight.

[0064] According to the twentieth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, in the titanium alloy: the oxygen content is 0 to 0.30; the iron content is 0 to 0.30; the nitrogen content is 0 to 0.05; the carbon content is 0 to 0.05; the hydrogen content is 0 to 0.015; and the content of each of niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper is 0 to 0.1, all as a weight percentage of the total weight of the titanium alloy.

[0065] According to the twenty-first non-limiting aspect of this disclosure, which may be used in combination with any or all of the foregoing aspects, a method of manufacturing a titanium alloy comprises: solution treating the titanium alloy at 1780℉ to 1800℉ for 4 hours; cooling the titanium alloy to ambient temperature at a rate depending on the cross-sectional thickness of the titanium alloy; aging the titanium alloy at 1025℉ to 1125℉ for 8 hours; and air-cooling the titanium alloy, wherein the titanium alloy has the composition described in any or all of the foregoing aspects.

[0066] According to the twenty-second non-limiting aspect of this disclosure, which can be used in combination with each or any of the foregoing aspects, the titanium alloy exhibits a strength of less than 8 x 10⁻⁶ at a temperature of at least 890℉ and a load of 52 ksi. -4 (24 hours) -1 The steady-state creep rate.

[0067] According to the twenty-third non-limiting aspect of this disclosure, which can be used in combination with each or any of the foregoing aspects, the titanium alloy exhibits an ultimate tensile strength of at least 130 ksi at 900℉.

[0068] According to the twenty-fourth non-limiting aspect of this disclosure, this disclosure also provides a titanium alloy comprising, by weight percentage of the total alloy weight: 2 to 7 aluminum; 0 to 5 tin; 0 to 5 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.05 to 2.0 germanium; 0 to 0.30 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0 to 0.05 carbon; 0 to 0.015 hydrogen; titanium; and impurities.

[0069] According to the twenty-fifth non-limiting aspect of this disclosure, which can be used in combination with each or any of the foregoing aspects, the titanium alloy exhibits a strength of less than 8 x 10⁻⁶ at a temperature of at least 890℉ and a load of 52 ksi. -4 (24 hours) -1 The steady-state creep rate.

[0070] According to the twenty-sixth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the titanium alloy further comprises 0 to 5 chromium as a weight percentage of the total alloy weight.

[0071] According to the twenty-seventh non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the titanium alloy further comprises, by weight percentage of the total alloy weight: 0 to 6.0 each of niobium, tungsten, vanadium, tantalum, manganese, nickel, hafnium, gallium, antimony, cobalt and copper.

[0072] According to the twenty-eighth non-limiting aspect of this disclosure, which can be used in combination with each or any of the foregoing aspects, the titanium alloy exhibits a strength of less than 8 x 10⁻⁶ at a temperature of at least 890℉ and a load of 52 ksi. -4 (24 hours) -1 The steady-state creep rate.

[0073] According to the twenty-ninth non-limiting aspect of this disclosure, which may be used in combination with each or any of the foregoing aspects, the titanium alloy further comprises 0 to 5 chromium as a weight percentage of the total alloy weight.

[0074] It will be understood that this specification describes those aspects of the invention that are relevant to a clear understanding of the invention. For the sake of simplicity, certain aspects that are obvious to those skilled in the art and therefore disadvantageous to a better understanding of the invention have not been presented. Although only a limited number of embodiments of the invention have been described herein as necessary, those skilled in the art will recognize, upon considering the foregoing description, that many modifications and variations of the invention can be employed. All such variations and modifications of the invention are intended to be covered by the foregoing description and the following claims.

Claims

1. A titanium alloy, comprising, by weight percentage of the total alloy weight, the following: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30% silicon; 0.1 to 2.0 germanium; 0.01 to 0.25 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0.001 to 0.05 carbon; 0 to 0.015 hydrogen; Niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper, each 0 to 0.1; titanium; and Impurities; The titanium alloy mentioned therein includes zirconium-silicon-germanium intermetallic precipitates.

2. The titanium alloy according to claim 1, comprising, by weight percentage of the total alloy weight, the following: 5.5 to 6.5 aluminum; 1.7 to 2.1 tin; 1.7 to 2.1 molybdenum; 3.4 to 4.4 zirconium; 0.03 to 0.11 silicon; 0.1 to 0.4 germanium; 0.01 to 0.30 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0.001 to 0.05 carbon; 0 to 0.015 hydrogen; Niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper, each 0 to 0.1; Titanium; and Impurities.

3. The titanium alloy according to claim 1, comprising, by weight percentage of the total alloy weight, the following: 5.9 to 6.0 aluminum; 1.9 to 2.0 tin; 1.8 to 1.9 molybdenum; 3.5 to 4.3 zirconium; 0.06 to 0.11 silicon; 0.1 to 0.4 germanium; 0.01 to 0.30 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0.001 to 0.05 carbon; 0 to 0.015 hydrogen; Niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper, each 0 to 0.1; Titanium; and Impurities.

4. The titanium alloy of claim 1, wherein the titanium alloy exhibits a strength of less than 8 × 10⁻⁶ kJ / m² at a temperature of at least 890 °F and a load of 52 kSi. -4 (24 hours) -1 The steady-state creep rate.

5. The titanium alloy according to claim 1, wherein the titanium alloy exhibits an ultimate tensile strength of at least 130 ksi at 900℉.

6. A method for manufacturing a titanium alloy, the method comprising: The titanium alloy was solution treated at 1780℉ to 1800℉ for 4 hours; The titanium alloy is cooled to ambient temperature at a rate depending on the cross-sectional thickness of the titanium alloy. The titanium alloy was aged at 1025℉ to 1125℉ for 8 hours. and The air-cooled titanium alloy, The titanium alloy described herein has the composition as described in claim 1.

7. A titanium alloy, comprising, by weight percentage of the total alloy weight: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 3.4 to 4.4 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; titanium; and Impurities; The titanium alloy mentioned therein includes zirconium-silicon-germanium intermetallic precipitates.

8. The titanium alloy according to claim 7, wherein the aluminum content in the alloy is 5.9 to 6.0% by weight of the total alloy weight.

9. The titanium alloy according to claim 7, wherein the tin content in the alloy is 1.7 to 2.1% by weight of the total alloy weight.

10. The titanium alloy of claim 7, wherein the tin content in the alloy is 1.9 to 2.0% by weight of the total alloy weight.

11. The titanium alloy of claim 7, wherein the molybdenum content in the alloy is 1.7 to 2.1% by weight of the total alloy weight.

12. The titanium alloy of claim 7, wherein the molybdenum content in the alloy is 1.8 to 1.9% by weight of the total alloy weight.

13. The titanium alloy of claim 7, wherein the zirconium content in the alloy is 3.5 to 4.3% by weight of the total alloy weight.

14. The titanium alloy of claim 7, wherein the silicon content in the alloy is from 0.03 to 0.11% by weight of the total alloy weight.

15. The titanium alloy of claim 7, wherein the silicon content in the alloy is from 0.06 to 0.11% by weight of the total alloy weight.

16. The titanium alloy of claim 7, wherein the germanium content in the alloy is 0.1 to 0.4% by weight of the total alloy weight.

17. A titanium alloy, comprising, by weight percentage of the total alloy weight: 2 to 7 aluminum; 0 to 5 tin; 0 to 5 molybdenum; 0.1 to 10.0 zirconium; 0.01 to 0.30 silicon; 0.05 to 0.4 germanium; 0 to 0.30 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0 to 0.05 carbon; 0 to 0.015 hydrogen; titanium; and Impurities; The titanium alloy mentioned therein includes zirconium-silicon-germanium intermetallic precipitates.

18. A titanium alloy, comprising, by weight percentage of the total alloy weight: 5.5 to 6.5 aluminum; 1.5 to 2.5 tin; 1.3 to 2.3 molybdenum; 3.4 to 4.4 zirconium; 0.01 to 0.30 silicon; 0.1 to 2.0 germanium; 0 to 0.30 oxygen; 0 to 0.30 iron; 0 to 0.05 nitrogen; 0 to 0.05 carbon; 0 to 0.015 hydrogen; Niobium, tungsten, hafnium, nickel, gallium, antimony, vanadium, tantalum, manganese, cobalt and copper, each 0 to 0.1; titanium; and Impurities; The titanium alloy mentioned therein includes zirconium-silicon-germanium intermetallic precipitates.

19. The titanium alloy of claim 18, wherein the aluminum content in the alloy is 5.9 to 6.0% by weight of the total alloy weight.

20. The titanium alloy of claim 18, wherein the tin content in the alloy is 1.7 to 2.1% by weight of the total alloy weight.

21. The titanium alloy of claim 18, wherein the tin content in the alloy is 1.9 to 2.0% by weight of the total alloy weight.

22. The titanium alloy of claim 18, wherein the molybdenum content in the alloy is 1.7 to 2.1% by weight of the total alloy weight.

23. The titanium alloy of claim 18, wherein the molybdenum content in the alloy is 1.8 to 1.9% by weight of the total alloy weight.

24. The titanium alloy of claim 18, wherein the zirconium content in the alloy is 3.5 to 4.3% by weight of the total alloy weight.

25. The titanium alloy of claim 18, wherein the silicon content in the alloy is from 0.03 to 0.11% by weight of the total alloy weight.

26. The titanium alloy of claim 18, wherein the silicon content in the alloy is from 0.06 to 0.11% by weight of the total alloy weight.

27. The titanium alloy of claim 18, wherein the germanium content in the alloy is 0.1 to 0.4% by weight of the total alloy weight.

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