This application relates to titanium alloys and, more particularly, to thixoforming of titanium alloys.
Titanium alloys offer high tensile strength over a broad temperature range, yet are relatively light weight. Furthermore, titanium alloys are resistant to corrosion. Therefore, titanium alloys are used in various demanding applications, such as aircraft components, medical devices and the like.
Plastic forming of titanium alloys is a costly process. The tooling required for plastic forming of titanium alloys must be capable of withstanding heavy loads during deformation. Therefore, the tooling for plastic forming of titanium alloys is expensive to manufacture and difficult to maintain due to high wear rates. Furthermore, it can be difficult to obtain complex geometries when plastic forming titanium alloys. Therefore, substantial additional machining is often required to achieve the desired shape of the final product, thereby further increasing costs.
Casting is a common alternative for obtaining titanium alloy products having more complex shapes. However, casting of titanium alloys is complicated by the high melting temperatures of titanium alloys, as well as the excessive reactivity of molten titanium alloys with mold materials and ambient oxygen.
Accordingly, titanium alloys are some of the most difficult metals to be processed in a cost-effective manner. Therefore, those skilled in the art continue with research and development efforts in the field of titanium alloys.
In one embodiment, the disclosed titanium alloy includes about 5 to about 33 percent by weight copper, about 1 to about 8 percent by weight iron, and titanium.
In another embodiment, the disclosed titanium alloy consists essentially of about 5 to about 33 percent by weight copper, about 1 to about 8 percent by weight iron, and balance titanium.
In yet another embodiment, the disclosed titanium alloy consists essentially of about 13 to about 33 percent by weight copper, about 3 to about 5 percent by weight iron, and balance titanium.
In one embodiment, the disclosed method for manufacturing a metallic article includes the steps of (1) heating a mass of titanium alloy to a thixoforming temperature, the thixoforming temperature being between a solidus temperature of the titanium alloy and a liquidus temperature of the titanium alloy, the titanium alloy including copper, iron and titanium; and (2) forming the mass into the metallic article while the mass is at the thixoforming temperature.
In another embodiment, the disclosed method for manufacturing a metallic article includes the steps of (1) heating a mass of titanium alloy to a thixoforming temperature, the thixoforming temperature being between a solidus temperature of the titanium alloy and a liquidus temperature of the titanium alloy, the titanium alloy including about 5 to about 33 percent by weight copper, about 1 to about 8 percent by weight iron, and titanium; and (2) forming the mass into the metallic article while the mass is at the thixoforming temperature.
Other embodiments of the disclosed titanium-copper-iron alloy and associated thixoforming method will become apparent from the following detailed description, the accompanying drawings and the appended claims.
Disclosed is a titanium-copper-iron alloy. When the compositional limits of the copper addition and the iron addition in the disclosed titanium-copper-iron alloy are controlled as disclosed herein, the resulting titanium-copper-iron alloy may be particularly well-suited for use in the manufacture of metallic articles by way of thixoforming.
Without being limited to any particular theory, it is believed that the disclosed titanium-copper-iron alloys are well-suited for use in the manufacture of metallic articles by way of thixoforming because the disclosed titanium-copper-iron alloys have a relatively broad solidification range. As used herein, “solidification range” refers to the difference (ΔT) between the solidus temperature and the liquidus temperature of the titanium-copper-iron alloy, and is highly dependent upon alloy composition. As one example, the solidification range of the disclosed titanium-copper-iron alloys may be at least about 50° C. As another example, the solidification range of the disclosed titanium-copper-iron alloys may be at least about 100° C. As another example, the solidification range of the disclosed titanium-copper-iron alloys may be at least about 150° C. As another example, the solidification range of the disclosed titanium-copper-iron alloys may be at least about 200° C. As another example, the solidification range of the disclosed titanium-copper-iron alloys may be at least about 250° C. As another example, the solidification range of the disclosed titanium-copper-iron alloys may be at least about 300° C.
The disclosed titanium-copper-iron alloys become thixoformable when heated to a temperature between the solidus temperature and the liquidus temperature of the titanium-copper-iron alloy. However, the advantages of thixoforming are limited when the liquid fraction of the titanium-copper-iron alloy is too high (processing becomes similar to casting) or too low (processing becomes similar to plastic metal forming). Therefore, it may be advantageous to thixoform when the liquid fraction of the titanium-copper-iron alloy is between about 30 percent and about 50 percent.
Without being limited to any particular theory, it is further believed that the disclosed titanium-copper-iron alloys are well-suited for use in the manufacture of metallic articles by way of thixoforming because the disclosed titanium-copper-iron alloys achieve a liquid fraction between about 30 percent and about 50 percent at temperatures significantly below traditional titanium alloy casting temperatures. In one expression, the disclosed titanium-copper-iron alloys achieve a liquid fraction between about 30 percent and about 50 percent at a temperature less than 1,200° C. In another expression, the disclosed titanium-copper-iron alloys achieve a liquid fraction between about 30 percent and about 50 percent at a temperature less than 1,150° C. In another expression, the disclosed titanium-copper-iron alloys achieve a liquid fraction between about 30 percent and about 50 percent at a temperature less than 1,100° C. In another expression, the disclosed titanium-copper-iron alloys achieve a liquid fraction between about 30 percent and about 50 percent at a temperature less than 1,050° C. In yet another expression, the disclosed titanium-copper-iron alloys achieve a liquid fraction between about 30 percent and about 50 percent at a temperature of about 1,010° C.
In one embodiment, disclosed is a titanium-copper-iron alloy having the composition shown in Table 1.
Thus, the disclosed titanium-copper-iron alloy may consist of (or consist essentially of) titanium (Ti), copper (Cu) and iron (Fe).
Those skilled in the art will appreciate that various impurities, which do not substantially affect the physical properties of the disclosed titanium-copper-iron alloy, may also be present, and the presence of such impurities will not result in a departure from the scope of the present disclosure. For example, the impurities content of the disclosed titanium-copper-iron alloy may be controlled as shown in Table 2.
The copper addition to the disclosed titanium-copper-iron alloy increases the liquid fraction at a given temperature. Therefore, without being limited to any particular theory, it is believed that the copper addition contributes to the thixoformability of the disclosed titanium-copper-iron alloy.
As shown in Table 1, the compositional limits of the copper addition to the disclosed titanium-copper-iron alloy range from about 5 percent by weight to about 33 percent by weight. In one variation, the compositional limits of the copper addition range from about 13 percent by weight to about 33 percent by weight. In another variation, the compositional limits of the copper addition range from about 15 percent by weight to about 30 percent by weight. In another variation, the compositional limits of the copper addition range from about 17 percent by weight to about 25 percent by weight. In yet another variation, the compositional limits of the copper addition range from about 18 percent by weight to about 22 percent by weight.
Iron is a strong β-stabilizer, but can increase density and cause embrittlement. Therefore, without being limited to any particular theory, it is believed that the iron addition retains the Ti-β phase during cooling, but without an excessive density increase and without causing significant embrittlement.
As shown in Table 1, the compositional limits of the iron addition to the disclosed titanium-copper-iron alloy range from about 1 percent by weight to about 8 percent by weight. In one variation, the compositional limits of the iron addition range from about 2 percent by weight to about 7 percent by weight. In another variation, the compositional limits of the iron addition range from about 3 percent by weight to about 6 percent by weight. In another variation, the compositional limits of the iron addition range from about 3 percent by weight to about 5 percent by weight. In yet another variation, iron is present at a concentration of about 4 percent by weight.
One general, non-limiting example of the disclosed titanium-copper-iron alloy has the composition shown in Table 3.
Referring to the phase diagram of
One specific, non-limiting example of the disclosed titanium-copper-iron alloy has the following nominal composition:
Ti-18Cu-4Fe
and the measured composition shown in Table 4.
PANDAT™ software (version 2014 2.0) from CompuTherm LLC of Middleton, Wis., was used to generate liquid fraction versus temperature data for the disclosed Ti-18Cu-4Fe alloy, assuming both equilibrium conditions and Scheil conditions. The results are shown in
Referring to
Another specific, non-limiting example of the disclosed titanium-copper-iron alloy has the following nominal composition:
Ti-20Cu-4Fe
and the measured composition shown in Table 5.
PANDAT™ software (version 2014 2.0) was used to generate liquid fraction versus temperature data for the disclosed Ti-20Cu-4Fe alloy, assuming both equilibrium conditions and Scheil conditions. The results are shown in
Referring to
Yet another specific, non-limiting example of the disclosed titanium-copper-iron alloy has the following nominal composition:
Ti-22Cu-4Fe
and the measured composition shown in Table 6.
PANDAT™ software (version 2014 2.0) was used to generate liquid fraction versus temperature data for the disclosed Ti-22Cu-4Fe alloy, assuming both equilibrium conditions and Scheil conditions. The results are shown in
Referring to
Accordingly, discloses are titanium-copper-iron alloys that are well-suited for thixoforming. Also, disclosed are methods for manufacturing a metallic article, particularly a titanium alloy article, by way of thixoforming.
Referring now to
At this point, those skilled in the art will appreciate that selection of a titanium alloy (Block 12) may include selecting a commercially available titanium alloy or, alternatively, selecting a non-commercially available titanium alloy. In the case of a non-commercially available titanium alloy, the titanium alloys may be custom made for use in the disclosed method 10.
As is disclosed herein, the solidification range may be one consideration during selection (Block 12) of a titanium alloy. For example, selection of a titanium alloy (Block 12) may include selecting a titanium-copper-iron alloy having a solidification range of at least 50° C., such as at least 100° C., or at least 150° C., or at least 200° C. or at least 250° C., or at least 300° C.
As is also disclosed herein, the temperature at which a liquid fraction between about 30 percent and about 50 percent is achieved may be another consideration during selection (Block 12) of a titanium alloy. For example, selection of a titanium alloy (Block 12) may include selecting a titanium-copper-iron alloy that achieves a liquid fraction between about 30 percent and about 50 percent at a temperature less than 1,200° C., such as a temperature less than 1,150° C., or a temperature less than 1,100° C., or a temperature less than 1,050° C.
At Block 14, a mass of the titanium alloy may be heated to a thixoforming temperature (i.e., a temperature between the solidus and liquidus temperatures of the titanium alloy). In one particular implementation, the mass of the titanium alloy may be heated to a particular thixoforming temperature, and the particular thixoforming temperature may be selected to achieve a desired liquid fraction in the mass of the titanium alloy. As one example, the desired liquid fraction may be about 10 percent to about 70 percent. As another example, the desired liquid fraction may be about 20 percent to about 60 percent. As yet example, the desired liquid fraction may be about 30 percent to about 50 percent.
At Block 16, the mass of the titanium alloy may optionally be maintained at the thixoforming temperature for a predetermined minimum amount of time prior to proceeding to the next step (Block 18). As one example, the predetermined minimum amount of time may be about 10 seconds. As another example, the predetermined minimum amount of time may be about 30 seconds. As another example, the predetermined minimum amount of time may be about 60 seconds. As another example, the predetermined minimum amount of time may be about 300 seconds. As yet another example, the predetermined minimum amount of time may be about 600 seconds.
At Block 18, the mass of the titanium alloy may be formed into a metallic article while the mass is at the thixoforming temperature. Various forming techniques may be used, such as, without limitation, casting and molding.
Accordingly, the disclosed titanium-copper-iron alloy and associated thixoforming method may facilitate the manufacture of net shape (or near net shape) titanium alloy articles at temperatures that are significantly lower than traditional titanium casting temperatures, and without the need for the complex/expensive tooling typically associated with plastic forming of titanium alloys. Therefore, the disclosed titanium-copper-iron alloy and associated thixoforming method have the potential to significantly reduce the cost of manufacturing titanium alloy articles.
Examples of the disclosure may be described in the context of an aircraft manufacturing and service method 100, as shown in
Each of the processes of method 100 may be performed or carried out by a system integrator, a third party, and/or an operator (e.g., a customer). For the purposes of this description, a system integrator may include without limitation any number of aircraft manufacturers and major-system subcontractors; a third party may include without limitation any number of venders, subcontractors, and suppliers; and an operator may be an airline, leasing company, military entity, service organization, and so on.
As shown in
The disclosed titanium-copper-iron alloy and associated thixoforming method may be employed during any one or more of the stages of the aircraft manufacturing and service method 100. As one example, components or subassemblies corresponding to component/subassembly manufacturing 108, system integration 110, and or maintenance and service 116 may be fabricated or manufactured using the disclosed titanium-copper-iron alloy and associated thixoforming method. As another example, the airframe 118 may be constructed using the disclosed titanium-copper-iron alloy and associated thixoforming method. Also, one or more apparatus examples, method examples, or a combination thereof may be utilized during component/subassembly manufacturing 108 and/or system integration 110, for example, by substantially expediting assembly of or reducing the cost of an aircraft 102, such as the airframe 118 and/or the interior 122. Similarly, one or more of system examples, method examples, or a combination thereof may be utilized while the aircraft 102 is in service, for example and without limitation, to maintenance and service 116.
The disclosed titanium-copper-iron alloy and associated thixoforming method is described in the context of an aircraft; however, one of ordinary skill in the art will readily recognize that the disclosed titanium-copper-iron alloy and associated thixoforming method may be utilized for a variety of applications. For example, the disclosed titanium-copper-iron alloy and associated thixoforming method may be implemented in various types of vehicle including, for example, helicopters, passenger ships, automobiles, marine products (boat, motors, etc.) and the like. Various non-vehicle applications, such as medical applications, are also contemplated.
Although various embodiments of the disclosed titanium-copper-iron alloy and associated thixoforming method have been shown and described, modifications may occur to those skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.
Number | Name | Date | Kind |
---|---|---|---|
4568398 | Wood et al. | Feb 1986 | A |
5865238 | Carden | Feb 1999 | A |
6666258 | Kono | Dec 2003 | B1 |
20020007883 | Doutre | Jan 2002 | A1 |
20100192727 | Withers | Aug 2010 | A1 |
Number | Date | Country |
---|---|---|
2156 850 | Oct 1985 | GB |
WO 9803686 | Jan 1998 | WO |
Entry |
---|
Lu et al., “Phase constitution and microstructure evolution of rapidly solidified Ti—Cu—Fe alloy,” Acta Physica Sinica, vol. 61, No. 21, 216102 (Year: 2012). |
He et al., “Effect of composition of microstructure and compressive mechanical properties in Ti—Cu—Fe—Sn—Nb alloys,” Materials Transactions, vol. 45, No. 5, pp. 1555-1560 (Year: 2004). |
Chen et al., Effect of Cu concentration on the semi-solid deformation behavior and microstructure of Ti—Cu alloy, Advances in Mechanical Engineering, v. 7, p. 1-10, (2015). |
Flemings, Semi-solid forming: the process and the path forward, Metallurgical Science and Technology, v. 18, p. 3-4, (2000). |
European Patent Office, “Extended European Search Report,” App. No. 18164884.1 (dated Jun. 15, 2018). |
Cardoso F.F et al: “Hexagonal martensite decomposition and phase precipitation in TiCu alloys”, Materials and Design, London GB. vol. 32, No. 8, (Mar. 16, 2011). |
Yongnan Chen et al: “Effect of Cu Content on thee Semi-Solid Formability and Mechanical Properties of Ti—Cu Alloys”, Rare Metal Materials and Engineering, vol. 45, No. 6 (Jun. 1, 2016). |
Zhang Erlin et al: “Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti—Cu sintered alloys”, Materials Science and Engineering C, Elsevier Science S.A. CH, vol. 69, (Jul. 20, 2016). |
Number | Date | Country | |
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20180281054 A1 | Oct 2018 | US |