A method for rapidly manufacturing a gamma-TiAl alloy target

Abstract

The application discloses a kind of γ-TiAl alloy target material fast manufacturing method, comprising: by additive system preparation interlayer thickness is 0.1~0.8mm Ti and Al pre-alloying deposition layer;Ti and Al pre-alloying deposition layer is placed in vacuum or atmosphere sintering furnace;In vacuum or atmosphere sintering furnace, sintering temperature 1200 ℃~1400 ℃ keeps warm for 4-8 hours, realizes mutual diffusion sintering between Ti and Al, complete alloying, obtains γ-TiAl alloy.The application can make full use of raw material, be suitable for various specifications and sizes target material product preparation, and equipment and manufacturing cost is low.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology and relates to a rapid manufacturing method for γ-TiAl alloy targets. Background Technology

[0002] With the gradual development and maturation of physical vapor deposition (PVD) technology, thin films and coatings are increasingly widely used in industrial fields. γ-TiAl alloy sputtering targets are a type of sputtering source used in physical vapor deposition (magnetron sputtering) to prepare Ti-Al-N hard coatings on workpiece surfaces. The deposited coatings possess advantages such as high hardness and chemical stability, and are mainly used in molds, cutting tools, and decorative applications. γ-TiAl alloys contain multiple deposition states, including 50 at.% Ti + 50% at.% Al, 40 at.% Ti + 60 at.% Al, etc., with TiAl (γ phase) as the dominant phase, or a small amount of Ti3Al (α phase).

[0003] Currently, γ-TiAl alloys are mainly produced using powder metallurgy and vacuum melting methods. Both processes have their drawbacks. Powder metallurgy includes hot pressing sintering and hot isostatic pressing (HIP). This involves sintering γ-TiAl alloy powder or a mixture of Ti and Al powders in a mold using bidirectional or multidirectional HIP for densification. The former, using γ-TiAl alloy powder, faces preparation difficulties due to its inherent brittleness and susceptibility to reactions with other alloys at 300-600℃, making powder preparation techniques (centrifugal atomization and gas atomization) unsuitable. The latter, sintering two pure metal powders, suffers from uneven mixing or, at sintering temperatures of 600-1400℃, multiple chemical reactions occur between the two phases, resulting in exothermic processes that threaten the reliability of the mold during densification. Furthermore, the degree of chemical reaction is difficult to control, leading to multiphase γ-TiAl alloy targets with significant differences in melting points between the different phases, negatively impacting the physical vapor deposition process of the target.

[0004] Hot pressing sintering involves uniformly mixing Al powder and Ti, followed by hot pressing and sintering. This method has a relatively low cost, but the product density is insufficient and the particle uniformity is inadequate due to the fact that only one phase is subjected to force during the forming process. Hot isostatic pressing can achieve a target density of >99%, but hot isostatic pressing equipment is expensive and the cladding material cannot be recycled, resulting in high target preparation costs.

[0005] In summary, the powder metallurgy method for preparing titanium-aluminum alloy targets involves mixing titanium powder and aluminum powder, then pressing and sintering the mixture in a mold. However, it suffers from the following problems: 1. High powder production costs and a long production process, especially since titanium powder preparation requires first forming rods or wires before centrifugal atomization or gas atomization; 2. High manufacturing costs due to the need for a one-time sintering mold, and the micron- or submicron-scale reaction of the powder may lead to segregation or uneven reaction; 3. Powder metallurgy is not suitable for forming complex structural components.

[0006] Although vacuum melting technology has a shorter process flow, the poor liquid fluidity and rapid solidification rate of γ-TiAl alloys easily lead to defects such as porosity and looseness, resulting in target material density that does not meet deposition requirements. Some technologies employ vacuum melting followed by hot isostatic pressing (HIP) for secondary sintering to close pores or looseness; however, as mentioned earlier, γ-TiAl alloys are inherently brittle, and microcracks can form internally during the pressing and sintering process, still preventing the target material from being used in engineering applications.

[0007] Due to the aforementioned process limitations, the industrially used γ-TiAl alloy sputtering targets suffer from poor quality stability, low yield, and high price. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a rapid manufacturing method for γ-TiAl alloy targets, which can utilize 100% of raw materials, is suitable for preparing target products of various specifications and sizes, and has low equipment and manufacturing costs, thus solving the problems existing in the prior art.

[0009] The technical solution adopted in this invention is a rapid manufacturing method for γ-TiAl alloy targets, comprising the following steps:

[0010] S1. Pre-alloyed deposited layers of Ti and Al with an interlayer thickness of 0.1–0.8 mm were prepared using an additive manufacturing system;

[0011] S2. Place the pre-alloyed Ti and Al deposited layers in a vacuum or atmosphere sintering furnace;

[0012] S3. In a vacuum or atmosphere sintering furnace, the sintering temperature is 1200℃~1400℃ and held for 4-8 hours to achieve interdiffusion sintering between Ti and Al, resulting in complete alloying and obtaining γ-TiAl alloy.

[0013] Furthermore, S1 includes the following steps:

[0014] S11. Based on the required γ-TiAl alloy target material composition, target material size and shape, establish a three-dimensional model, and import the metal droplet motion planning path corresponding to the three-dimensional model into the control system;

[0015] S12. Based on the composition, size, and shape of the γ-TiAl alloy target, set the heat source parameters and the wire feed speed in the wire feeding module in the control system.

[0016] S13. Place the elemental Ti metal wire and Al metal wire in the processing chamber and adjust the orientation relationship between the Ti metal wire and Al metal wire and the heat source;

[0017] S14. Control the planar motion trajectory and speed of the heat source module and the wire feeding module according to the planned path;

[0018] S15. Based on the heat source parameters and wire feed speed set in S12, intermittently and alternately feed Ti metal wire and Al metal wire;

[0019] S16. The heat source module melts the Ti or Al metal wire below to form droplets, which are then dropped into the alumina boat and solidified into dot-shaped pre-alloyed γ-TiAl target material to form the designed deposition layer and thickness.

[0020] S17. Move the heat source module and wire feeding module according to the set speed and planned path to gradually form a planar pre-alloyed γ-TiAl target material;

[0021] S18. Return to step S14 to form the second planar layer until the forming process of the three-dimensional target material is completed.

[0022] Furthermore, S12 includes the following steps:

[0023] S12-1. Convert the atomic ratio of Ti and Al in γ-TiAl into a mass ratio;

[0024] S12-2. Calculate the feed rate of Ti metal wire and Al metal wire per unit time based on the wire diameter and mass ratio.

[0025] Furthermore, in S15, the feeding speed of the titanium wire is 1.8-10 mm / s, and the feeding speed of the aluminum wire is 1-6 mm / s.

[0026] Furthermore, in S13, the elemental Ti metal wire is a solid Ti metal wire with a purity greater than 4N and a diameter less than 1.2mm; the elemental Al metal wire is a solid Al metal wire with a purity greater than 4N and a diameter less than 1.2mm.

[0027] Furthermore, in step S3, the vacuum degree of the vacuum furnace is not less than 10. -3 Pa.

[0028] Furthermore, in S3, the oxygen content in the atmosphere sintering furnace is not higher than 2000 ppm.

[0029] Furthermore, the additive manufacturing system includes a wire feeding module and a heat source module located in the processing chamber, as well as a vacuum component for providing a vacuum environment for the processing chamber; characterized in that titanium-aluminum target material is prepared by a combination of additive manufacturing fitting alloying and sintering alloying; the wire feeding module includes at least two wire feeders, which feed Ti metal wire and Al metal wire respectively;

[0030] The heat source module is located above the wire feeding module and provides an energy source for melting the metal wire;

[0031] An alumina boat is positioned directly below the molten droplet of the Ti or Al metal wire to hold the target material for droplet formation.

[0032] It also includes a control module, which is connected to the wire feeding module and the heat source module respectively. The control module is used to determine the heat source parameters, the wire feeding speed in the wire feeding module, the motion trajectory and motion speed of the heat source module and the wire feeding module according to the composition, size and shape of the target material, and send them to the wire feeding module and the heat source module.

[0033] Furthermore, the heat source module is an electron beam or a plasma arc.

[0034] The beneficial effects of this invention are:

[0035] 1. This invention does not have the problems of uneven composition or uneven chemical reaction in powder metallurgy preparation technology, and eliminates the serious problem of γ-TiAl casting defects in vacuum melting technology.

[0036] 2. This invention has a short processing cycle, high yield, and can be applied to near-net-shape forming of γ-TiAl targets of any specification. After forming, only fine machining is required to meet industrial use requirements.

[0037] 3. The γ-TiAl alloy target prepared by this invention is suitable for any Ti and Al element ratio, and the phase composition is controllable. It has low equipment investment costs and low product manufacturing costs, eliminating the costs of powder preparation and mold making. It overturns traditional preparation methods, achieving integrated preparation and phase formation.

[0038] 4. This invention is carried out in a high vacuum environment, and the γ-TiAl alloy target material prepared has a low oxygen content.

[0039] 5. According to the present invention, traditional welding machines and wire feeders can be modified to realize the rapid additive manufacturing system for γ-TiAl alloy targets of the present invention. At the same time, the method and steps of the present invention can realize the forming of γ-TiAl targets, which has strong technical operability. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart illustrating the implementation steps of an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the structure of an embodiment of the present invention. Detailed Implementation

[0043] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1,

[0045] An additive manufacturing system includes: a processing chamber, a wire feeding module, a heat source module, a control module, and a vacuum assembly;

[0046] The wire feeding module and heat source module are located inside the processing chamber, and the vacuum assembly is mechanically connected to the processing chamber.

[0047] The heat source module provides the energy source for the processing;

[0048] The wire feeding module is located below the heat source module. The wire feeding module includes a wire feeder and metal wire, which feeds or provides raw materials for the processing. The wire feeder in the wire feeding module is connected to Ti metal wire and Al metal wire respectively.

[0049] An alumina boat is placed inside the processing chamber, directly below the heat source module and the wire feeding module, to load the γ-TiAl target material that is about to be formed;

[0050] The wire feeding module and the heat source module are respectively connected to the control module. The control module is used to transmit the wire feeding speed and current value (i.e. power) to the wire feeding module and the heat source module based on the analysis of the target material composition characteristics, and to receive path planning data from the three-dimensional model data.

[0051] The vacuum level inside the processing chamber shall not be less than 10. -3 Pa, titanium alloys, aluminum alloys and the resulting titanium-aluminum alloys are all active metals that readily react in the atmosphere at temperatures above 400°C; the heat source module is an electron beam or a plasma arc.

[0052] The rapid additive manufacturing system for γ-TiAl alloy targets requires three-dimensional modeling of the composition and structural characteristics of the γ-TiAl target, and design of the additive manufacturing process based on the composition and three-dimensional model, namely, adjusting the wire feeding speed of the wire feeding module and the power of the heat source module.

[0053] Example 2,

[0054] A rapid manufacturing method for γ-TiAl alloy sputtering targets, such as Figure 1-2 As shown, it includes the following steps:

[0055] S1. Using the additive manufacturing system described in Example 1, a pre-alloyed deposition layer of Ti and Al with an interlayer thickness of 0.1 to 0.8 mm is prepared; if the interlayer thickness is too thick, the amount of metal in each layer is too large, and the degree of alloying of the two metals deteriorates.

[0056] S11. Based on the composition and structural characteristics (size and shape of the target material) of the γ-TiAl alloy target, a three-dimensional model is established, and the three-dimensional model data is used to generate a planning path for controlling the movement of the heat source module and imported into the control system.

[0057] S12. Based on the composition and structural characteristics of the γ-TiAl alloy target, set the heat source parameters and wire feeding parameters (feeding speed) in the wire feeding module in the control system;

[0058] S12-1. Convert the atomic ratio of Ti and Al in γ-TiAl into a mass ratio;

[0059] S12-2. Calculate the feed rate of the two types of wire per unit time based on the wire diameter and mass ratio;

[0060] Calculate the feed length h of Ti wire and Al wire per unit time, i.e., the feed speed, according to formula (1):

[0061]

[0062] Where: m is the mass of Ti or Al wire fed per second (both are high-purity wires with a purity greater than 99.9%), ρ is the wire density, and R is the wire diameter.

[0063] The atomic ratio of Ti to Al in γ-TiAl is 1:1. Therefore, Timass% = 47.8 ÷ (26.2 + 47.8) * 100% (2)

[0064]

[0065] Where Timass% represents the mass fraction of Ti, and Tiat.% represents the percentage of Ti atomic mass.

[0066] S13. Place high-purity elemental Ti wire and Al wire in the processing chamber and adjust the orientation relationship between the Ti wire and Al wire and the heat source; the high-purity Ti wire is a solid Ti metal wire with a purity greater than 4N and a diameter less than 1.2mm; the high-purity Al wire is a solid Al metal wire with a purity greater than 4N and a diameter less than 1.2mm; in this embodiment, the minimum wire diameter is 0.1mm.

[0067] S14. Control the movement trajectory and speed of the heat source module and wire feeding module according to the planned path;

[0068] S15. Based on the heat source parameters and wire feeding parameters set in S12, the molten wire is fed to Ti and Al wires. The wire feeder is a servo motor. In the wire feeding system, the wire feeder feeds the metal wires according to the wire feeding speed. The Ti wire feeding speed is 3.6 mm / s, with a 1-second pause. During the pause, the Al wire feeder feeds the wire at 2 mm / s, with a 1-second pause. This process is repeated, with the wires fed in a cross-feeding manner. The wire feeding ratio of the two materials is always 1.8:1.

[0069] S16. The heat source uses thermal energy to melt the Ti or Al metal wire located below it, forming droplets, which are then dropped into the alumina boat and solidified into "dot"-shaped pre-alloyed γ-TiAl target material (incompletely alloyed unstable phase), forming the designed deposition layer and thickness.

[0070] S17. Move the heat source module and wire feeding module according to the set speed and planned path to gradually form a "surface"-shaped pre-alloyed γ-TiAl target material;

[0071] S18. Return to step S14 until the pre-alloyed γ-TiAl alloy target forming process is completed, realizing the integrated rapid forming of "point"-"line"-"surface"-"body".

[0072] S2. Place the pre-alloyed Ti and Al deposited layers in a vacuum or atmosphere sintering furnace;

[0073] S3. Sintering at 1300℃ for 6 hours in a vacuum or atmosphere sintering furnace to achieve interdiffusion sintering between Ti and Al, thus achieving complete alloying and obtaining a titanium-aluminum intermetallic compound, namely γ-TiAl alloy.

[0074] Vacuum furnaces or atmosphere sintering furnaces use graphite heating belts, while high-temperature heating belts contain molybdenum and graphite, but molybdenum reacts with titanium and aluminum; the vacuum level of the vacuum furnace is not lower than 10. -3 The oxygen content in the Pa and argon furnace is no higher than 2000 ppm. Titanium alloys, aluminum alloys, and the titanium-aluminum alloys produced by the reaction are all active metals that are prone to reaction in the atmosphere at temperatures above 400℃.

[0075] The experimental data for the γ-TiAl alloy prepared in Example 2 are shown in Table 1.

[0076] Table 1 Comparison of Embodiment 2 of the present invention with the prior art

[0077] Powder metallurgy technology ＞1000 98 γ, α, β-Ti, Al, etc. long Vacuum melting technology ＞500 90 γ, α Moderate Example 2 ＞50 100 γ, α short

[0078] The higher the oxygen content as an impurity element, the more yellow and discolored the alloy will appear, which will seriously affect its performance. The γ-TiAl alloy target material prepared in Example 2 of this invention has a low oxygen content, which can overcome the above problems.

[0079] Example 3,

[0080] A rapid manufacturing method for γ-TiAl alloy sputtering targets.

[0081] Except for S15, the feeding speed of titanium wire with a diameter of 1.2 mm is 1.8 mm / s, and the feeding speed of aluminum wire with a diameter of 1.2 mm is 1 mm / s; the sintering temperature in S3 is 1200℃, and the holding time is 4 hours; the remaining steps are the same as in Example 2.

[0082] Example 4,

[0083] A rapid manufacturing method for γ-TiAl alloy sputtering targets.

[0084] Except for S15, the feeding speed of titanium wire with a diameter of 0.8 mm is 10 mm / s, and the feeding speed of aluminum wire with a diameter of 0.8 mm is 6 mm / s; the sintering temperature in S3 is 1400℃, and the holding time is 8 hours; the remaining steps are the same as in Example 2.

[0085] The experimental data for the TiAl alloys prepared in Examples 3-4 are shown in Table 2.

[0086] Table 2 Experimental data for Examples 3 and 4

[0087] Example 3 0.3 γ-TiAl Example 4 0.8 γ-TiAl

[0088] Example 5,

[0089] A rapid manufacturing method for TiAl alloy sputtering targets.

[0090] In S15, the feeding speed of the titanium wire was 3.6 mm / s, and the feeding speed of the aluminum wire was 2 mm / s; the remaining steps were the same as in Example 2. The sintered phase composition was γ-TiAl.

[0091] Comparative Example 1,

[0092] A rapid manufacturing method for TiAl alloy sputtering targets.

[0093] The sintering temperature in S3 is 1000℃, and the holding time is 6 hours; the remaining steps are the same as in Example 2.

[0094] Comparative Example 2,

[0095] A rapid manufacturing method for TiAl alloy sputtering targets.

[0096] The sintering temperature in S3 is 1500℃, and the holding time is 6 hours; the remaining steps are the same as in Example 2.

[0097] The experimental data of the TiAl alloys prepared in Comparative Examples 1-2 are shown in Table 3.

[0098] Table 3 Comparison of sintering parameters

[0099] 1000℃ α-Ti, Al / 1500℃ γ-TiAl Uncontrollable, deformable

[0100] Comparative Example 3,

[0101] A rapid manufacturing method for TiAl alloy sputtering targets.

[0102] In S15, the feeding speed of the titanium wire is 1.2 mm / s, and the feeding speed of the aluminum wire is 1 mm / s; the remaining steps are the same as in Example 2. The phase composition after sintering is α-Ti+Ti3Al.

[0103] This invention breaks through the constraints of traditional processes. Based on the principle of in-situ reaction, it combines additive manufacturing technology with reaction sintering technology, eliminating the need for molds and achieving one-time integral molding of titanium-aluminum alloy blades. Cross-feeding of the filaments ensures thorough mixing of the two molten droplets. This cross-feeding relies on a precise CNC module, which inputs the calculated filament feed speed into the control module. Common filament feeding methods involve continuous single-filament feeding, while this invention uses intermittent alternating feeding of two filaments. In this embodiment, the interval between the intermittent cross-feeding of the two filaments is 1 second; exceeding this time results in poor uniformity.

[0104] In S3, the reaction between Ti and Al involves two processes: Ti + Al → Al + Ti + γ-TiAl → γ-TiAl + α-TiAl. The outcome of these two processes is determined not only by the mass ratio but also by the reaction sintering temperature and time. The reaction process must be controlled; incomplete or over-sintering will prevent the formation of the γ phase.

[0105] The γ-TiAl alloy obtained in this invention is an intermetallic compound, inherently brittle, with difficult-to-control phase transformation and extremely challenging processing. It cannot be directly additively prepared using γ-TiAl alloy wires, making its preparation far more difficult than that of ordinary titanium alloy Ti6Al4V three-dimensional parts. This invention utilizes an electron beam melting device, where both melting and reaction occur in a high-vacuum environment. Titanium-aluminum alloys are extremely reactive metals and are highly susceptible to oxidation without a high-vacuum environment.

[0106] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A rapid manufacturing method for γ-TiAl alloy sputtering targets, characterized in that, Includes the following steps: S1. Pre-alloyed deposited layers of Ti and Al with an interlayer thickness of 0.1~0.8 mm were prepared using an additive manufacturing system; S2. Place the pre-alloyed Ti and Al deposited layers in a vacuum or atmosphere sintering furnace; S3. In a vacuum or atmosphere sintering furnace, the sintering temperature is 1200℃~1400℃ and held for 4-8 hours to achieve interdiffusion sintering between Ti and Al, and complete alloying to obtain γ-TiAl alloy. S1 includes the following steps: S11. Based on the required γ-TiAl alloy target material composition, target material size and shape, establish a three-dimensional model, and import the metal droplet motion planning path corresponding to the three-dimensional model into the control system; S12. Based on the composition, size, and shape of the γ-TiAl alloy target, set the heat source parameters and the wire feed speed in the wire feeding module in the control system. S13. Place the elemental Ti metal wire and Al metal wire in the processing chamber and adjust the orientation relationship between the Ti metal wire and Al metal wire and the heat source; S14. Control the planar motion trajectory and speed of the heat source module and the wire feeding module according to the planned path; S15. Based on the heat source parameters and wire feeding speed set in S12, Ti metal wire and Al metal wire are intermittently fed alternately; the Ti wire feeding speed is 3.6 mm / s, pauses for 1 second, and during the pause, the Al wire feeder feeds wire at 2 mm / s, pauses for 1 second; this process is repeated, with alternating feeding; the feeding ratio of the two materials is always 1.8:

1. S16. The heat source module melts the Ti or Al metal wire below to form droplets, which are then dropped into the alumina boat and solidified into dot-shaped pre-alloyed γ-TiAl target material to form the designed deposition layer and thickness. S17. Move the heat source module and wire feeding module according to the set speed and planned path to gradually form a planar pre-alloyed γ-TiAl target material; S18. Return to step S14 to form the second planar layer until the forming process of the three-dimensional target material is completed.

2. The rapid manufacturing method for γ-TiAl alloy sputtering targets according to claim 1, characterized in that, S12 includes the following steps: S12-1. Convert the atomic ratio of Ti and Al in γ-TiAl into the mass ratio; S12-2. Calculate the feed rate of Ti metal wire and Al metal wire per unit time based on the wire diameter and mass ratio.

3. The rapid manufacturing method for γ-TiAl alloy sputtering targets according to claim 1, characterized in that, In S13, the elemental Ti metal wire is a solid Ti metal wire with a purity greater than 4N and a diameter less than 1.2mm; the elemental Al metal wire is a solid Al metal wire with a purity greater than 4N and a diameter less than 1.2mm.

4. The rapid manufacturing method for γ-TiAl alloy sputtering targets according to claim 1, characterized in that, In step S3, the vacuum degree of the vacuum furnace is not less than 10. -3 Pa.

5. The rapid manufacturing method for γ-TiAl alloy sputtering targets according to claim 1, characterized in that, In S3, the oxygen content in the atmosphere sintering furnace is not higher than 2000 ppm.

6. The rapid manufacturing method for γ-TiAl alloy sputtering targets according to claim 1, characterized in that, The additive manufacturing system includes a wire feeding module and a heat source module located in the processing chamber, as well as a vacuum component for providing a vacuum environment for the processing chamber; characterized in that titanium-aluminum target material is prepared by a combination of additive manufacturing fitting alloying and sintering alloying; the wire feeding module includes at least two wire feeders, which feed Ti metal wire and Al metal wire respectively; The heat source module is located above the wire feeding module and provides an energy source for melting the metal wire; An alumina boat is positioned directly below the molten droplet of the Ti or Al metal wire to hold the target material for droplet formation. It also includes a control module, which is connected to the wire feeding module and the heat source module respectively. The control module is used to determine the heat source parameters, the wire feeding speed in the wire feeding module, the motion trajectory and motion speed of the heat source module and the wire feeding module according to the composition, size and shape of the target material, and send them to the wire feeding module and the heat source module.

7. The rapid manufacturing method for γ-TiAl alloy sputtering targets according to claim 1, characterized in that, The heat source module is an electron beam or a plasma arc.

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