KR20230093185A - Titanium-Cobalt alloy and associated thixoforming method - Google Patents

Abstract

Disclosed in the present invention are a titanium alloy comprising about 5 to about 27 wt% of cobalt and titanium and a methods for preparing the same. The titanium-cobalt alloy and a thixoforming method related thereto according to the present invention enable a titanium alloy product in a net shape (or net-like shape) at temperatures substantially lower than conventional titanium casting temperatures, without the need for complex and expensive tooling typically associated with plastic forming of titanium alloys.

Description

Titanium-Cobalt alloy and associated thixoforming method {Titanium-Cobalt alloy and associated thixoforming method}

This application relates to titanium alloys, and in particular to thixoforming titanium alloys.

Titanium alloys offer high tensile strength over a wide temperature range, but are relatively light. Additionally, titanium alloys are resistant to corrosion. Therefore, titanium alloys are used in a variety of demanding applications, such as aircraft components, medical equipment, and the like.

Plastic forming of titanium alloys is an expensive process. The tooling required for plastic forming of titanium alloys must be able to withstand heavy loads during deformation. Therefore, tooling for plastic forming of titanium alloys is expensive to manufacture and difficult to maintain due to high wear rates. In addition, it is difficult to obtain complex geometries when plastic forming titanium alloys. Therefore, substantially additional processing is often required to achieve the desired shape of the final product, thereby further increasing the cost.

Casting is a common alternative for obtaining titanium alloy products with more complex shapes. However, casting of titanium alloys is complicated by the excessive reactivity of the molten titanium alloy with the mold material and ambient oxygen, as well as the high melting point of the titanium alloy.

Thus, titanium alloys are some of the most difficult metals to process cost-effectively. Therefore, those skilled in the art are continuing research and development efforts in the field of titanium alloys.

In one embodiment, the disclosed titanium alloy includes from about 5 to about 27 percent cobalt by weight.

In another embodiment, the disclosed titanium alloy consists essentially of about 5 to about 27 percent cobalt by weight, and the balance titanium.

In another embodiment, the disclosed titanium alloy consists essentially of about 13 to about 27 percent cobalt and balance titanium by weight.

In one embodiment, the disclosed method for fabricating a metallic article includes (1) heating a mass of a titanium alloy to a thixoforming temperature, wherein the thixoforming temperature is a solidus temperature of the titanium alloy and between the liquidus temperature of the titanium alloy, the titanium alloy comprising cobalt and titanium; and (2) forming the agglomerate into a metallic article while the agglomerate is at the thixoforming temperature. equipped with

In another embodiment, the disclosed method for fabricating a metallic article includes (1) heating a mass of a titanium alloy to a thixoforming temperature, wherein the thixoforming temperature is equal to or greater than the solidus temperature of the titanium alloy. and (2) the mass is at the thixoforming temperature. While forming a lump with a metallic article; is made equipped with.

Other embodiments of the disclosed titanium-cobalt alloys and related thixoforming methods will become apparent from the following detailed description, accompanying drawings and appended claims.

1 is a phase diagram of a titanium-cobalt alloy;
2A and 2B are graphs of liquid fraction versus temperature for three exemplary titanium alloys generated assuming equilibrium conditions (FIG. 2A) and Scheil conditions (FIG. 2B);
3A-3D show four exemplary titanium alloys, specifically Ti-17.5Co (FIG. 3A), Ti-18.5Co (FIG. 3B), Ti-19.5Co (FIG. 3C) and Ti-20.5Co (FIG. 3D). It is a photograph showing the microstructure (when maintained at 1060 ° C) versus time for
4 is a flow diagram illustrating one embodiment of a disclosed method for manufacturing a metallic article;
5 is a flow diagram of an aircraft manufacturing and servicing method;
6 is a block diagram of an aircraft.

A titanium-cobalt alloy is disclosed. When the compositional limits of copper addition and iron addition in the disclosed titanium-cobalt alloys are controlled as disclosed herein, the resulting titanium-cobalt alloy will be particularly best-suited for the manufacture of metallic articles by thixoforming processes. can

Without wishing to be bound by any particular theory, it is believed that the disclosed titanium-cobalt alloys are best-suited for the manufacture of metallic articles by thixoforming processes because they have a relatively wide solidification range. As used herein, “solidification range” refers to the difference between the solidus temperature and the liquidus temperature (ΔT) of a titanium-cobalt alloy and is highly dependent on the alloy composition. As an example, the solidification range of the disclosed titanium-cobalt alloy can be at least about 50°C. As another example, the solidification range of the disclosed titanium-cobalt alloys can be at least about 100°C. As another example, the solidification range of the disclosed titanium-cobalt alloys can be at least about 150°C. As another example, the solidification range of the disclosed titanium-cobalt alloys can be at least about 200°C. As another example, the solidification range of the disclosed titanium-cobalt alloys can be at least about 250°C. As another example, the solidification range of the disclosed titanium-cobalt alloys can be at least about 300°C.

The disclosed titanium-cobalt alloys thixoform when heated to a temperature between the solidus temperature and the liquidus temperature of the titanium-cobalt alloy. However, the benefits of thixoforming are limited when the liquid phase of the titanium-cobalt alloy is too high (the process becomes casting-like) or too low (the process becomes plastic-metal forming). Therefore, it is advantageous for thixoforming when the liquid phase of the titanium-cobalt alloy is about 30% and about 50%.

Without wishing to be bound by any particular theory, the disclosed titanium-cobalt alloys have metallic properties because the disclosed titanium-cobalt alloys achieve a liquid phase between about 30 percent and about 50 percent at temperatures substantially below conventional titanium alloy casting temperatures. It is further considered best-suited for use in the manufacture of articles. In one form, the disclosed titanium-cobalt alloy achieves a liquidus rate of between about 30 percent and about 50 percent at temperatures below 1,200°C. In another form, the disclosed titanium-cobalt alloy achieves a liquidus rate of between about 30 percent and about 50 percent at temperatures below 1,150°C. In another form, the disclosed titanium-cobalt alloy achieves a liquidus rate of between about 30 percent and about 50 percent at temperatures below 1,100°C. In another form, the disclosed titanium-cobalt alloy achieves a liquidus ratio of between about 30 percent and about 50 percent at temperatures below 1,050°C. In another form, the disclosed titanium-cobalt alloy achieves a liquidus rate of between about 30 percent and about 50 percent at temperatures below 1,025°C.

In one embodiment, a titanium-cobalt alloy having the composition shown in Table 1 is disclosed.

Element Coverage (wt%) Co 5 - 27 Ti remain

Accordingly, the disclosed titanium-cobalt alloy may consist (consist essentially of) of titanium (Ti) and cobalt (Co).

It will be appreciated by those skilled in the art that various impurities may also be present that do not materially affect the physical properties of the disclosed titanium-cobalt alloys, and the presence of such impurities will not depart from the scope of the present disclosure. For example, the impurity content of the disclosed titanium-cobalt alloy can be controlled as shown in Table 2.

impurities maximum (wt%) O 0.25 N 0.03 different elements, respectively 0.10 other elements, whole 0.30

Without being limited to any particular theory, it is believed that the addition of cobalt slightly increases the hardness of cast and forged alloys and contributes to the thixoformability of the disclosed titanium-cobalt alloys.

As shown in Table 1, the composition limit for cobalt additions for the disclosed titanium-cobalt alloys is between about 5 percent and 27 percent by weight. In one variation, the composition limit for cobalt addition is between about 10 percent and about 27 percent by weight. In another variation, the composition limit for cobalt addition is between about 13 percent and 27 percent by weight. In another variation, the compositional limit of the cobalt addition is between about 15 percent and 25 percent by weight. In another variation, the compositional limit of the cobalt addition is between about 17 percent and 23 percent by weight. In another variation, the composition limit for cobalt addition is between about 17 percent and about 21 percent by weight.

Example 1

(Ti-13-27Co)

One general, non-limiting example of the disclosed titanium-cobalt alloy has the composition shown in Table 3.

element Concentration (wt%) Co 13 - 27 Ti remain

Referring to the phase diagram of FIG. 1 and, in particular, the lattice region of FIG. 1, the disclosed Ti-13-27Co alloy has a relatively low solidus temperature (about 1,015° C.) and a relatively wide solidification range. Therefore, the disclosed Ti-13-27Co alloy is best-suited for thixoforming.

example 2

(Ti-17.5Co)

One particular, non-limiting example of a disclosed titanium-cobalt alloy has the following nominal composition:

Ti-17.5Co

and the measured composition shown in Table 4.

element Concentration (wt%) Ti remain Co 17.6 ± 0.2 O 0.157 ± 0.010 N 0.007 ± 0.001

CompuTherm LLC's PANDAT software (2014 version 2.0) of Middleton, Wisconsin was used to generate liquid phase versus temperature data for the disclosed Ti-17.5Co alloy, assuming both equilibrium and Scheil conditions. Results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on data from FIG. 2A (equilibrium conditions), the disclosed Ti-17.5Co alloy has a solidification range of about 335°C, a solidus temperature of about 1,015°C and a liquidus temperature of about 1,350°C.

Referring to FIG. 3A, the disclosed Ti-17.5Co alloy is heated to 1,060° C.—a temperature between the solidus and liquidus temperatures (i.e., thixoforming temperature)—and micrographs are obtained at 0 seconds, 60 seconds, 300 seconds and Taken at 600 seconds. The micrograph shows how the disclosed Ti-17.5Co alloy has a globular microstructure at 1,060 °C that becomes more and more globular with time. Therefore, the disclosed Ti-17.5Co alloy is particularly best-suited for thixoforming.

example 3

(Ti-18.5Co)

Another specific, non-limiting example of the disclosed titanium-cobalt alloy has the following formal configuration:

Ti-18.5Co

and the measured composition shown in Table 5.

element Concentration (wt%) Ti remain Co 18.9 ± 0.2 O 0.154 ± 0.012 N 0.010 ± 0.007

PANDAT software (2014 version 2.0) was used to generate liquid phase versus temperature data for the disclosed Ti-18.5Co alloy, assuming both equilibrium and Scheil conditions. Results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on the data from FIG. 2A (equilibrium condition), the disclosed Ti-18.5Co alloy has a solidification range of about 306°C, a solidus temperature of about 1,015°C and a liquidus temperature of about 1,321°C.

Referring to FIG. 3B, the disclosed Ti-18.5Co alloy is heated to 1,060° C.—a temperature between the solidus and liquidus temperatures (i.e., thixoforming temperature)—and micrographs are taken at 0 sec, 60 sec, 300 sec, and 600 sec. was filmed on The micrograph shows how the disclosed Ti-18.5Co alloy has a spherical microstructure at 1,060°C that becomes more and more spherical with time. Therefore, the disclosed Ti-18.5Co alloy is particularly best-suited for thixoforming.

example 4

(Ti-19.5Co)

Another specific, non-limiting example of the disclosed titanium-cobalt alloy has the following formal configuration:

Ti-19.5Co

and the measured composition shown in Table 6.

element Concentration (wt%) Ti remain Co 19.6 ± 0.2 O 0.147 ± 0.003 N 0.007 ± 0.002

PANDAT software (2014 version 2.0) was used to generate liquid phase versus temperature data for the disclosed Ti-19.5Co alloy, assuming both equilibrium and Scheil conditions. Results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on the data from FIG. 2A (equilibrium condition), the disclosed Ti-19.5Co alloy has a solidification range of about 276°C, a solidus temperature of about 1,015°C and a liquidus temperature of about 1,291°C.

Referring to FIG. 3C, the disclosed Ti-19.5Co alloy is heated to 1,060° C.—a temperature between the solidus and liquidus temperatures (i.e., thixoforming temperature)—and the micrographs are plotted at 0 seconds, 60 seconds, 300 seconds, and 600 seconds. was filmed on The micrograph shows how the disclosed Ti-19.5Co alloy has a spherical microstructure at 1,060°C that becomes more and more spherical with time. Therefore, the disclosed Ti-19.5Co alloy is particularly best-suited for thixoforming.

example 5

(Ti-20.5Co)

Another specific, non-limiting example of the disclosed titanium-cobalt alloy has the following formal configuration:

Ti-20.5Co

and the measured composition shown in Table 7.

element Concentration (wt%) Ti remain Co 20.5 ± 0.3 O 0.143 ± 0.004 N 0.006 ± 0.001

PANDAT software (2014 version 2.0) was used to generate liquid phase versus temperature data for the disclosed Ti-20.5Co alloy, assuming both equilibrium and Scheil conditions. Results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on data from FIG. 2A (equilibrium conditions), the disclosed Ti-20.5Co alloy has a solidification range of about 244°C, a solidus temperature of about 1,015°C and a liquidus temperature of about 1,259°C.

Referring to FIG. 3D, the disclosed Ti-20.5Co alloy is heated to 1,060° C.—a temperature between the solidus and liquidus temperatures (i.e., thixoforming temperature)—and the micrographs are plotted at 0 sec, 60 sec, 300 sec, and 600 sec. was filmed on The micrograph shows how the disclosed Ti-20.5Co alloy has a spherical microstructure at 1,060°C that becomes more and more spherical with time. Therefore, the disclosed Ti-20.5Co alloy is particularly best-suited for thixoforming.

Accordingly, the best-suited titanium-cobalt alloys for thixoforming are disclosed. Also disclosed is a method for producing metal articles, particularly titanium alloy articles, by way of thixoforming.

Referring to FIG. 4 , one embodiment of a disclosed method for fabricating a metal article, generally designated 10 , begins at block 12 with the selection of a titanium alloy for use as a starting material. can start Selection of a titanium alloy (block 12) may include selecting a titanium-cobalt alloy having the composition shown in Table 1 above.

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 otherwise selecting a non-commercially available titanium alloy. will be. In the case of non-commercially available titanium alloys, the titanium alloy may be custom made for the disclosed method 10.

As disclosed herein, the extent of solidification may be one consideration during selection of a titanium alloy (Block 12). For example, a selection of titanium alloys (block 12) may have 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, for example. It may include selecting a titanium-cobalt alloy having.

As also disclosed herein, the temperature achieved at a liquidus rate between about 30 percent and about 50 percent may be another consideration during selection of the titanium alloy (Block 12). For example, the selection of a titanium alloy (block 12) is about 30 percent at a temperature less than 1,200°C, or less than 1,150°C, or less than 1,100°C, or less than 1,050°C, for example. and selecting a titanium-cobalt alloy that achieves a liquidus ratio between about 50 percent.

At block 14, the mass of titanium alloy may be heated to a thixoforming temperature (ie, a temperature between the solidus and liquidus temperatures of the titanium alloy). In one particular implementation, the mass of titanium alloy may be heated to a particular thixoforming temperature, and the particular thixoforming temperature may be selected to achieve a desired liquidus ratio in the mass of titanium alloy. As an example, the desired liquidity ratio may be from about 10 percent to about 70 percent. As another example, the desired liquidity ratio may be from about 20 percent to about 60 percent. As another example, the desired liquidity ratio may be from about 30 percent to about 50 percent.

At block 16, the mass of titanium alloy may optionally be held at the thixoforming temperature for a predetermined minimum time before proceeding to the next step (block 18). As an example, the predetermined minimum time may be about 10 seconds. As another example, the predetermined minimum time may be about 30 seconds. As another example, the predetermined minimum time may be about 60 seconds. As another example, the predetermined minimum time may be about 300 seconds. As another example, the predetermined minimum time may be about 600 seconds.

At block 18, a chunk of titanium alloy may be formed into a metallic article while the chunk is at the thixoforming temperature. A variety of shaping techniques may be used, such as, without limitation, casting and molding.

Thus, the disclosed titanium-cobalt alloys and related thixoforming methods can form reticulated (or close to reticulated) materials at temperatures substantially lower than conventional titanium casting temperatures, without the need for the complex and expensive tooling normally associated with plastic forming of titanium alloys. ) can enable the manufacture of titanium alloy articles. Therefore, the disclosed titanium-cobalt alloys and related thixoforming methods have the potential to substantially reduce the cost of titanium alloy articles.

An example of this disclosure may be described in the context of aircraft manufacturing and service method 100, shown in FIG. 5, and aircraft 102, shown in FIG. During pre-production, aircraft manufacturing and service method 100 may include specification and design of aircraft 102 and material procurement 106 . During manufacturing, component/subassembly manufacturing (108) and system integration (110) of aircraft 102 takes place. The aircraft 102 may then go through certification and delivery 112 to be placed in service 114 . While in service by a customer, aircraft 102 is scheduled for routine maintenance and service (116), which may include modification, reconfiguration, refurbishment, and the like. do.

Each process of method 100 may be performed or implemented by a system integrator, a third party, and/or an operator (eg, a customer). For purposes of this description, system integrators may include, without limitation, any number of aircraft manufacturers and major-system subcontractors; Third parties may include, without limitation, any number of vendors, subcontractors, and suppliers; Operators can be airlines, rental companies, military contractors, service organizations, and the like.

As shown in FIG. 6 , an aircraft 102 produced by the exemplary method 100 may include an airframe 118 having a plurality of systems 120 and an interior 122 . Examples of the plurality of systems 120 include one or more of a propulsion system 124, an electrical system 126, a hydraulic system 128, and an environmental system 130. can do.

The disclosed titanium-cobalt alloys and related thixoforming methods may be used during any one or more steps of aircraft manufacturing and service method 100 . As an example, components and subassemblies corresponding to component/subassembly manufacturing (108), system integration (110), and/or maintenance and service (116) may be made using the disclosed titanium-cobalt alloys and related thixoforming methods. It can be manufactured and manufactured using As another example, base 118 may be constructed using the disclosed titanium-cobalt alloy and related thixoforming methods. Additionally, one or more device examples, method examples, or combinations thereof may be used during component/subassembly fabrication (108) and/or system integration (110), for example, with the airframe (118) and/or interior (122). It can be utilized by reducing the cost of the same aircraft 102 or by substantially speeding up assembly of the aircraft. Similarly, one or more of the system examples, method examples, or combinations thereof may be utilized while in service 102 for maintenance and service 116, for example and without limitation.

The disclosed titanium-cobalt alloys and related thixoforming methods are described in the context of aircraft; One or more skilled in the art will readily appreciate that the disclosed titanium-cobalt alloys and related thixoforming methods can be utilized for a variety of applications. For example, the disclosed titanium-cobalt alloys and related thixoforming methods can be implemented in various types of vehicles, including, for example, helicopters, passenger carriers, automobiles, maritime related products (boats, motors, etc.), and the like. there is. A variety of non-vehicle applications are also contemplated, such as medical applications.

Although various embodiments of the disclosed titanium-cobalt alloys and related thixoforming methods have been shown and described, modifications may occur to those skilled in the art upon reading this application. This application contains such amendments and is limited only by the scope of the claims.

Claims (15)

about 5 to about 27 percent cobalt by weight; and
A titanium alloy comprising titanium. According to claim 1,
the cobalt is present from about 10 to about 27 percent by weight; or
the cobalt is present from about 13 to about 27 percent by weight; or
the cobalt is present from about 15 to about 25 percent by weight; or
the cobalt is present from about 17 to about 23 percent by weight; or
wherein the cobalt is present from about 17 to about 21 percent by weight; 3. Titanium alloy according to claim 1 or claim 2, characterized in that oxygen is present as an impurity in a concentration of at most about 0.25 percent by weight. 4. Titanium alloy according to any one of claims 1 to 3, characterized in that nitrogen is present as an impurity in a concentration of at most about 0.03 percent by weight. The titanium alloy according to any one of claims 1 to 4, characterized in that it consists of the cobalt and the titanium. Heating a mass of titanium alloy to a thixoforming temperature, wherein the thixoforming temperature is between the solidus temperature of the titanium alloy and the liquidus temperature of the titanium alloy, the titanium alloy comprising: cobalt and titanium; heating step of doing; and
shaping the mass into the metallic article while the mass is at the thixoforming temperature. 7. The method of claim 6, further comprising the step of holding the mass at the temperature for at least about 60 seconds prior to said forming of the mass into the metallic article. 8. The method of claim 6 or claim 7 further comprising the step of holding the mass at the temperature for at least about 600 seconds prior to said forming of the mass into the metallic article. way for. 9. A metallic article according to any one of claims 6 to 8, further comprising the step of selecting the titanium alloy such that the difference between the solidus temperature and the liquidus temperature is at least 200°C. way to do it. 10. A metallic article according to any one of claims 6 to 9, further comprising the step of selecting the titanium alloy such that the difference between the solidus temperature and the liquidus temperature is at least 250°C. way to do it. 11. The method of any one of claims 6-10, further comprising selecting the titanium alloy to have a liquidus ratio between about 30 percent and about 50 percent at a temperature less than 1,200°C; or
and selecting the titanium alloy to have a liquidus ratio between about 30 percent and about 50 percent at a temperature below 1,100°C. 12. The method of any one of claims 6-11, wherein the cobalt is present in the titanium alloy from about 5 to about 27 percent by weight. According to any one of claims 6 to 11,
The method of claim 1 , wherein the cobalt is present from about 13 to about 27 percent by weight in the titanium alloy. 12. The method of any one of claims 6-11, wherein the cobalt is present from about 17 to about 23 percent by weight in the titanium alloy. 15. A method according to any one of claims 6 to 14, wherein the titanium alloy consists of the cobalt and the titanium.

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