KR102627655B1 - Titanium-Cobalt alloy and associated thixoforming method - Google Patents

Abstract

A titanium alloy containing from about 5 to about 27 percent by weight cobalt and titanium and a method of making the same.

Description

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, etc.

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. Moreover, it is difficult to obtain complex geometric structures when plastic forming titanium alloy. 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 high melting point of titanium alloys, as well as the excessive reactivity of the molten titanium alloys with the mold material and ambient oxygen.

Therefore, titanium alloys are some of the most difficult metals to process from a cost-effective perspective. 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 by weight cobalt, and the balance titanium.

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

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

In another embodiment, the disclosed method for making a metallic article includes the steps of (1) heating a mass of titanium alloy to a thixoforming temperature, wherein the thixoforming temperature is the solidus temperature of the titanium alloy; and (2) the mass is at the thixoforming temperature. It is comprised of a step of forming a lump with a metallic article.

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

Figure 1 is a phase diagram of a titanium-cobalt alloy;
Figures 2A and 2B are graphs of liquid fraction versus temperature for three exemplary titanium alloys generated assuming equilibrium (Figure 2A) and Scheil conditions (Figure 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). This is a picture showing the microstructure (when maintained at 1060℃) versus time;
4 is a flow diagram illustrating one embodiment of the disclosed method for manufacturing a metallic article;
5 is a flow diagram of an aircraft manufacturing and servicing method;
Figure 6 is a block diagram of the aircraft.

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

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

The disclosed titanium-cobalt alloy thixoforms 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 liquidus fraction of the titanium-cobalt alloy is too high (making the process similar to casting) or too low (making the process similar to plastic metal forming). Therefore, it is advantageous for thixoforming when the liquid phase ratio of the titanium-cobalt alloy is about 30 percent and about 50 percent.

Without being bound by any particular theory, the disclosed titanium-cobalt alloy may be metallic because the disclosed titanium-cobalt alloy achieves a liquidus content of between about 30 percent and about 50 percent at temperatures substantially below conventional titanium alloy casting temperatures. It is further considered to be best suited for the manufacture of articles. In one form, the disclosed titanium-cobalt alloy achieves a liquidus content 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 content 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 content 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 content 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 content 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 Range (wt%) Co 5 - 27 Ti remain

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

Those skilled in the art will understand that various impurities may also be present that do not substantially affect the physical properties of the disclosed titanium-cobalt alloy, and that 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 different elements, whole 0.30

Without wishing to be bound by any particular theory, it is believed that the addition of cobalt slightly increases the hardness of the cast and forged alloy and contributes to the thixoformability of the disclosed titanium-cobalt alloy.

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

Example 1

(Ti-13-27Co)

A non-limiting example of one typical disclosed titanium-cobalt alloy has the configuration 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 pattern 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 the disclosed titanium-cobalt alloy has the following nominal composition:

Ti-17.5Co

and the measured constructs shown in Table 4.

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

PANDAT software (2014 version 2.0) from CompuTherm LLC, Middleton, Wisconsin, was used to generate liquidus versus temperature data for the disclosed Ti-17.5Co alloy, assuming both equilibrium and Scheil conditions. The results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on the data from Figure 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 taken at 0 seconds, 60 seconds, 300 seconds, and Filmed at 600 seconds. The micrograph shows how the disclosed Ti-17.5Co alloy has a spherical microstructure at 1,060°C that becomes increasingly globular over 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 constructs 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 liquidus versus temperature data for the disclosed Ti-18.5Co alloy, assuming both equilibrium and Scheil conditions. The results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on the data from Figure 2A (equilibrium conditions), 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 was heated to 1,060°C—a temperature between the solidus and liquidus temperatures (i.e., thixoforming temperature)—and micrographed at 0 seconds, 60 seconds, 300 seconds, and 600 seconds. was filmed in The micrograph shows how the disclosed Ti-18.5Co alloy has a spherical microstructure at 1,060°C that becomes increasingly spherical over 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 constructs 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 liquidus versus temperature data for the disclosed Ti-19.5Co alloy, assuming both equilibrium and Scheil conditions. The results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on the data from Figure 2A (equilibrium conditions), 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 Figure 3C, the disclosed Ti-19.5Co alloy was heated to 1,060°C—a temperature between the solidus and liquidus temperatures (i.e., thixoforming temperature)—and micrographed at 0 seconds, 60 seconds, 300 seconds, and 600 seconds. was filmed in The micrograph shows how the disclosed Ti-19.5Co alloy has a spherical microstructure at 1,060°C that becomes increasingly spherical over 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 constructs 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 liquidus versus temperature data for the disclosed Ti-20.5Co alloy, assuming both equilibrium and Scheil conditions. The results are shown in Figure 2a (equilibrium conditions) and Figure 2b (Scheil conditions). Based on the data from Figure 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 Figure 3D, the disclosed Ti-20.5Co alloy was heated to 1,060°C—a temperature between the solidus and liquidus temperatures (i.e., thixoforming temperature)—and micrographed at 0 seconds, 60 seconds, 300 seconds, and 600 seconds. was filmed in The micrograph shows how the disclosed Ti-20.5Co alloy has a spherical microstructure at 1,060°C that becomes increasingly spherical over time. Therefore, the disclosed Ti-20.5Co alloy is particularly best-suited for thixoforming.

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

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

At this point, one skilled in the art will understand that the 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. For 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 a consideration during selection of titanium alloy (block 12). For example, the selection of titanium alloy (block 12) may be such that the solidification range is at least 50°C, for example at least 100°C, or at least 150°C, or at least 200°C, or at least 250°C, or at least 300°C. It may include the step of selecting a titanium-cobalt alloy having.

Also disclosed herein, the temperature achieved at a liquidus content of 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 titanium alloy (block 12) may be such that, for example, at temperatures below 1,200°C, or below 1,150°C, or below 1,100°C, or below 1,050°C, about 30 percent and selecting a titanium-cobalt alloy that achieves a liquidus content of between about 50 percent.

In block 14, a chunk of titanium alloy may be heated to the thixoforming temperature (i.e., a temperature between the solidus and liquidus temperatures of the titanium alloy). In one particular implementation, a chunk of titanium alloy can be heated to a specific thixoforming temperature, and the specific thixoforming temperature can be selected to achieve a desired liquidus rate in the chunk of titanium alloy. As an example, the desired liquid content may be from about 10 percent to about 70 percent. As another example, the desired liquid content may be from about 20 percent to about 60 percent. As another example, the desired liquid content may be about 30 percent to about 50 percent.

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

In block 18, a lump of titanium alloy can be formed into a metallic article while the lump is at the thixoforming temperature. Various forming techniques may be used, for example, without limitation, casting and molding.

Accordingly, the disclosed titanium-cobalt alloy and related thixoforming method provide a net-shape (or near-net 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. ) can enable the manufacture of titanium alloy articles. Therefore, the disclosed titanium-cobalt alloy and associated thixoforming method have the potential to substantially reduce the cost of titanium alloy articles.

Examples of the present disclosure may be described in the context of aircraft manufacturing and servicing method 100, shown in FIG. 5, and aircraft 102, shown in FIG. 6. During pre-production, aircraft manufacturing and servicing methods 100 may include specification and design of aircraft 102 and material procurement 106. During fabrication, component/subassembly manufacturing 108 and system integration of the aircraft 102 occur. Aircraft 102 may then go through certification and delivery 112 to be placed in service 114. While in service by a customer, the aircraft 102 is scheduled for routine maintenance and service (116), which may include modification, reconfiguration, refurbishment, etc. do.

Each process of method 100 may be performed or implemented by a system integrator, a third party, and/or an operator (e.g., 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 sellers, subcontractors, and suppliers; The operator may be an airline, leasing company, military contractor, service organization, etc.

As shown in FIG. 6 , aircraft 102 produced by example method 100 may include an airframe 118 having a plurality of systems 120 and interiors 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 alloy and related thixoforming method may be used during any one or more steps of the aircraft manufacturing and servicing method 100. As one example, components and subassemblies corresponding to component/subassembly manufacturing 108, system integration 110, and/or maintenance and service 116 may be performed using the disclosed titanium-cobalt alloy and associated thixoforming method. It can be manufactured and manufactured using. As another example, airframe 118 can 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, e.g., with the airframe 118 and/or interior 122. This could 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 example, without limitation, for maintenance and service (116).

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

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

Claims (15)

A method for manufacturing a metal article, comprising:
Selecting a titanium alloy to have a liquidus content of between 30 percent and 50 percent, wherein the titanium alloy: consists of 17.6 to 20.5 percent by weight cobalt, balanced titanium and impurities, wherein the impurities are up to 0.25 percent by weight. containing oxygen, up to 0.03 percent by weight nitrogen, up to 0.1 percent by weight each of the other elements, and up to 0.3 percent by weight all of the other elements;
heating the 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;
maintaining the mass at the thixoforming temperature for at least 600 seconds; and
After the holding step, forming the lump into the metal article while the lump is at the thixoforming temperature. 2. The method of claim 1, further comprising selecting the titanium alloy such that the difference between the solidus temperature and the liquidus temperature is at least 100°C. 2. The method of claim 1, further comprising selecting the titanium alloy such that the difference between the solidus temperature and the liquidus temperature is at least 200°C. 2. The method of claim 1, further comprising selecting the titanium alloy such that the difference between the solidus temperature and the liquidus temperature is at least 250°C. 2. The method of claim 1, wherein the metal article is a mesh-shaped titanium alloy article. 2. The method of claim 1, wherein the thixoforming temperature is selected such that the mass of titanium alloy achieves a desired liquid phase. 7. The method of claim 6, wherein the thixoforming temperature is selected such that the mass of titanium alloy achieves a liquidus content of between 30 percent and 50 percent. 8. The method of claim 7, wherein the thixoforming temperature is selected such that the mass of titanium alloy achieves a liquidus content of 30 percent. 2. The method of claim 1, wherein the metal article is an aircraft component. 2. The method of claim 1, wherein selecting the titanium alloy comprises selecting the titanium alloy to have a liquidus content of between 30 percent and 50 percent at a temperature of less than 1,200° C. method for. 2. The method of claim 1, wherein selecting the titanium alloy comprises selecting the titanium alloy to have a liquidus content of between 30 percent and 50 percent at a temperature of less than 1,100° C. method for. 2. The method of claim 1, wherein selecting the titanium alloy comprises selecting the titanium alloy to have a liquidus content of between 30 percent and 50 percent at a temperature of less than 1,050° C. method for. delete delete delete