Single tungsten-phase-rich tungsten-titanium alloy and preparation method thereof

Abstract

The invention discloses a single tungsten-rich phase tungsten-titanium alloy and a preparation method thereof. According to the method, W powder and Ti powder serve as raw materials and are sequentially subjected to the steps of mixing, cold isostatic pressing, vacuum hot degassing, hot isostatic pressing and high-temperature treatment, and finally the single tungsten-phase-rich tungsten-titanium alloy is obtained. According to the method, the tungsten-titanium mixed powder is subjected to cold isostatic pressing, vacuum hot degassing and hot isostatic pressing treatment, and the fully-compact tungsten-titanium alloy with the evenly-distributed structure is obtained; then through high-temperature treatment, the diffusion degree of tungsten and titanium is improved, and the microscopic structure is regulated and controlled; and finally, the tungsten-titanium alloy with a single tungsten-rich phase microscopic structure, full compactness, equiaxial crystal grains and uniform size distribution is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of refractory alloy target material preparation, and particularly relates to a single tungsten-rich phase tungsten-titanium alloy and a preparation method thereof. BACKGROUND

[0002] In the wafer manufacturing and chip packaging steps in the chip manufacturing process, metal target materials are needed, wherein the W-10wt% Ti alloy target material is a commonly used refractory alloy target material. The WTi alloy thin film prepared by using the W-10wt% Ti alloy target material as a diffusion barrier layer can prevent Al and Cu from diffusing with the substrate Si and SiO2 on a large scale and causing circuit failure. When the W-10wt% Ti alloy target material is subjected to sputtering film coating, the thin film usually contains particle defects. Research shows that the particle defects are mainly caused by the titanium-rich phase. The microstructure of the W-10wt% Ti alloy usually contains a tungsten-rich phase and a titanium-rich phase. Therefore, in order to reduce the particle defects of the thin film, the content of the titanium-rich phase in the target material must be reduced and the content of the tungsten-rich phase must be increased.

[0003] As can be seen from the W-Ti binary phase diagram, the WTi alloy with a Ti mass ratio of 10% is a single solid solution under ideal thermodynamic conditions, and the microstructure thereof should be a single tungsten-rich phase. However, the W-10wt% Ti alloy is generally prepared by a powder metallurgy method. Influenced by the powder parameters of the W powder and the Ti powder and the sintering process, W and Ti are difficult to fully diffuse, and the sintering structure is extremely difficult to achieve a single phase structure and uniform organization. The alloy usually contains a large amount of titanium-rich phase.

[0004] Patent application CN201510727120.6 discloses a preparation method of a low titanium-rich phase tungsten-titanium alloy. The method mainly adopts high-temperature sintering and rapid cooling technology, and can maintain the tungsten-rich phase structure. However, the rapid cooling is easy to produce a large internal stress, resulting in cracking of the alloy.

[0005] Patent application CN200810239844.6 discloses a tungsten-titanium target material with high purity and high tungsten-rich phase content and a preparation method thereof. The method adds a third powder such as Nb, Mo, Cr, Ta or the like to stabilize the tungsten-rich phase. However, the third element in the tungsten-titanium target material may reduce the final use performance of the thin film. SUMMARY

[0006] In view of the problem that the tungsten-titanium target material contains a titanium-rich phase, the application aims to provide a single tungsten-rich phase tungsten-titanium alloy and a preparation method thereof. The composition of the tungsten-titanium alloy is 90wt% tungsten and 10wt% titanium, the microstructure thereof is a single tungsten-rich phase, the density thereof is greater than 99%, and the grains thereof are equiaxed and uniformly distributed.

[0007] The single tungsten-rich phase tungsten-titanium alloy provided by the application has the following element composition: 90wt% tungsten and 10wt% titanium.

[0008] The microstructure of the tungsten-titanium alloy is a single tungsten-rich phase; the grains are equiaxed and have uniform size distribution.

[0009] The application provides a method for preparing the single tungsten-rich phase tungsten-titanium alloy, which comprises the following steps:

[0010] 1) weighing tungsten powder and titanium powder according to a weight ratio, and uniformly mixing to obtain tungsten-titanium mixed powder;

[0011] 2) cold isostatic pressing the tungsten-titanium mixed powder to obtain a tungsten-titanium blank;

[0012] 3) placing the tungsten-titanium blank into a package, sealing and welding, connecting the package to a vacuum pump, and placing into a high-temperature furnace to perform vacuum heat degassing, thereby obtaining a high-vacuum package;

[0013] 4) hot isostatic pressing the high-vacuum package to obtain a fully dense sintered blank with uniform microstructure distribution;

[0014] 5) high-temperature treatment of the sintered blank to obtain the single tungsten-rich phase tungsten-titanium alloy.

[0015] In step 1) of the above method, the average particle size of the tungsten powder is 1-10 μm, and specifically 5 μm; the average particle size of the titanium powder is 20-40 μm, and specifically 30 μm.

[0016] The purity of the tungsten powder and the titanium powder is ≥99.9%. The mixing time is indefinite, as long as the mixing is uniform.

[0017] In step 2), the pressure in the cold isostatic pressing step is 50-200 MPa, and specifically 130-150 MPa; the time is 3-20 min, and specifically 5 min. Cold isostatic pressing can improve the loading density, make the shape more regular, reduce the subsequent processing amount, and at the same time, can improve the contact area of the W powder and the Ti powder, which is beneficial to subsequent densification and element diffusion.

[0018] In step 3), the material constituting the package is stainless steel or carbon steel.

[0019] In the vacuum heat degassing step in step 3), the temperature for vacuum heat degassing is 500-900 ℃; the vacuum degree is at least 2E-3 Pa; and the holding time is 5-10 h.

[0020] In the step 4) hot isostatic pressing step, the temperature is 1000-1300 DEG C; specifically, 1200 DEG C; the pressure is 100-150 MPa; specifically, 130 MPa; the holding time is 60-240 min; specifically, 180 min. If the process parameters of the hot isostatic pressing are below the range, the density may not be qualified; if the process parameters of the hot isostatic pressing are beyond the range, the cost of the product is increased, and energy is wasted. The hot isostatic pressing temperature of 1300 DEG C is much lower than the temperature of the tungsten-titanium alloy prepared by other sintering processes (such as vacuum hot pressing, vacuum sintering, etc.), and the material has uniform distribution of microstructure, and the grain is equiaxed and has uniform size distribution.

[0021] The method further comprises, after the step (4) of hot isostatic pressing, a step of turning and machining to remove the canning.

[0022] In the step 5) high-temperature treatment step, the high-temperature treatment temperature is 1400 DEG C-1800 DEG C; specifically, 1500 DEG C; and the holding time is 60-180 min; specifically, 120 min.

[0023] The step 5) high-temperature treatment is performed in a high-temperature furnace; the atmosphere in the furnace is vacuum, argon or flowing hydrogen. The purpose of controlling the atmosphere in the high-temperature furnace is to prevent oxidation of the alloy.

[0024] In addition, the application of the single tungsten-rich phase tungsten-titanium alloy as a target material also belongs to the protection scope of the present application.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] 1. The present application adopts the pressing and sintering process of cold isostatic pressing and hot isostatic pressing, so that the alloy is fully dense (>99%), the microstructure is uniform, the grain is equiaxed and has uniform size distribution. Meanwhile, the highest temperature of the hot isostatic pressing in the present experiment is 1300 DEG C, the requirement for the equipment is lower, and the use cost is lower.

[0027] 2. In order to control the microstructure, the fully dense tungsten-titanium alloy after the hot isostatic pressing is subjected to high-temperature treatment, W and Ti are fully diffused at high temperature, and a single tungsten-rich phase tungsten-titanium alloy is formed; the atmosphere in the furnace is vacuum, argon or flowing hydrogen, so as to prevent oxidation of the alloy.

[0028] 3. The tungsten-titanium alloy provided by the present application has a single tungsten-rich phase microstructure, the density can reach more than 99%, the grain is equiaxed and has uniform size distribution, the cost is low, the process is simple, and the present application is suitable for mass industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1(a) is a microstructure morphology diagram of a tungsten-titanium alloy prepared by a traditional preparation method;

[0030] Figure 1(b) is a microstructure morphology diagram of the tungsten-titanium alloy prepared by the method of the present application. In the figure, a. traditional preparation method; b. the method of the present application. DETAILED DESCRIPTION

[0031] The present application will be further described in conjunction with specific examples, but the present application is not limited to the following examples. The methods are all conventional methods unless otherwise specified. The raw materials are all commercially available unless otherwise specified.

[0032] Example 1, preparation of single tungsten-rich phase tungsten-titanium alloy

[0033] (1) Powder mixing step: W powder (99.9%) with an average particle size of 5 μm and Ti powder (99.9%) with an average particle size of 30 μm were weighed according to a weight ratio of 90:10 and mixed for 6 h.

[0034] (2) Cold isostatic pressing step: the tungsten-titanium mixed powder was placed in a mold for cold isostatic pressing at a pressure of 150 MPa for 3 min to obtain a tungsten-titanium blank;

[0035] (3) Vacuum thermal degassing step: the tungsten-titanium blank was placed in a package, sealed and welded, the package was connected to a vacuum pump and placed in a high-temperature furnace, the maximum temperature was 900℃, the vacuum degree was at least 2E -3 Pa, and maintained for 5 h to obtain a high-vacuum package;

[0036] (4) Hot isostatic pressing step: the high-vacuum package was subjected to hot isostatic pressing and sintering at a temperature of 1000℃ and a pressure of 150 MPa for 180 min to obtain a sintered blank, and the density of the sintered blank was 99.2%;

[0037] (5) High-temperature treatment step: the sintered blank was subjected to high-temperature treatment at a temperature of 1800℃ for 120 min to obtain the single tungsten-rich phase tungsten-titanium alloy provided by the present application.

[0038] The tungsten-titanium alloy obtained in this example was subjected to wire cutting, and then sample preparation was performed, and its microstructure was observed by scanning electron microscopy, and it was found that almost all of them were tungsten-rich phases and did not contain titanium-rich phases, as shown in Figure 1(b). Through density testing and metallographic analysis, the density was 99.5%, and the grains were equiaxed and the grain size distribution was uniform.

[0039] Example 2

[0040] (1) Powder mixing step: W powder (99.9%) with an average particle size of 5 μm and Ti powder (99.9%) with an average particle size of 30 μm were weighed according to a weight ratio of 90:10 and mixed for 6 h.

[0041] (2) Cold isostatic pressing step: the tungsten-titanium mixed powder is put into a mold for cold isostatic pressing, the pressure is 130 MPa, and the pressure maintaining time is 5 min, to obtain a tungsten-titanium blank;

[0042] (3) Vacuum hot degassing step: the tungsten-titanium blank is put into a package, sealed, connected to a vacuum pump, and put into a high-temperature furnace, the maximum temperature is 900℃, the vacuum degree is at least 2E -3 Pa, and maintained for 5 h to obtain a high-vacuum package;

[0043] (4) Hot isostatic pressing step: the high-vacuum package is subjected to hot isostatic pressing and sintering, the hot isostatic pressing temperature is 1300℃, the pressure is 130 MPa, and the pressure maintaining and heat preserving time is 180 min, to obtain a sintered blank, and the density of the sintered blank is 99.7%;

[0044] (5) High-temperature treatment step: the sintered blank is subjected to high-temperature treatment, the high-temperature treatment temperature is 1400℃, and the heat preserving time is 120 min, to obtain the single tungsten-rich phase tungsten-titanium alloy provided by the application.

[0045] The tungsten-titanium alloy obtained in this embodiment is subjected to wire cutting, and then sample preparation, and the microstructure is observed by a scanning electron microscope, and it is found that the content of the tungsten-rich phase is about 95%, and the content of the titanium-rich phase is about 5%. Through density testing and metallographic analysis, the density is 99.8%, and the grains are equiaxed and uniformly distributed in size.

[0046] Example 3

[0047] (1) Powder mixing step: W powder (99.9%) with an average particle size of 10 μm and Ti powder (99.9%) with an average particle size of 40 μm are weighed according to the weight ratio of 90:10, and mixed for 6 h.

[0048] (2) Cold isostatic pressing step: the tungsten-titanium mixed powder is put into a mold for cold isostatic pressing, the pressure is 150 MPa, and the pressure maintaining time is 3 min, to obtain a tungsten-titanium blank;

[0049] (3) Vacuum hot degassing step: the tungsten-titanium blank is put into a package, sealed, connected to a vacuum pump, and put into a high-temperature furnace, the maximum temperature is 900℃, the vacuum degree is at least 2E -3 Pa, and maintained for 5 h to obtain a high-vacuum package;

[0050] (4) Hot isostatic pressing step: the high-vacuum package is subjected to hot isostatic pressing and sintering, the hot isostatic pressing temperature is 1200℃, the pressure is 150 MPa, and the pressure maintaining and heat preserving time is 180 min, to obtain a sintered blank, and the density of the sintered blank is 99.5%;

[0051] (5) high-temperature treatment step, the sintered blank is subjected to high-temperature treatment, the high-temperature treatment temperature is 1500 DEG C, the holding time is 120 min, and a single tungsten-rich phase tungsten-titanium alloy is obtained.

[0052] The tungsten-titanium alloy obtained in the example is subjected to wire cutting, and then sample preparation, microstructure observation by a scanning electron microscope shows that the content of the tungsten-rich phase is about 93%, and the content of the titanium-rich phase is about 7%. Through density testing and metallographic analysis, the density is 99.6%, and the grain is equiaxed and the grain size distribution is uniform.

Claims

1. A single tungsten-rich phase tungsten-titanium alloy, having an elemental composition of 90wt% tungsten and 10wt% titanium. The tungsten-titanium alloy has a single tungsten-rich phase microstructure, and the grains are equiaxed and have a uniform size distribution. 2.A method for preparing the single tungsten-rich phase tungsten-titanium alloy of claim 1, comprising: 1) weighing tungsten powder and titanium powder according to a weight ratio, mixing them to obtain a tungsten-titanium mixed powder; 2) cold isostatic pressing the tungsten-titanium mixed powder to obtain a tungsten-titanium blank; 3) placing the tungsten-titanium blank into a can, sealing the can, connecting the can to a vacuum pump, and placing the can into a high-temperature furnace to perform vacuum thermal degassing, thereby obtaining a high-vacuum can; 4) hot isostatic pressing the high-vacuum can to obtain a sintered blank; 5) high-temperature treating the sintered blank to obtain the single tungsten-rich phase tungsten-titanium alloy.

3. The method of claim 2, wherein: In the step 1), the average particle size of the tungsten powder is 1-10 μm, and the average particle size of the titanium powder is 20-40 μm. The purity of the tungsten powder and the titanium powder is ≥99.9%.

4. The method according to claim 2 or 3, characterized in that: In the step 2), the pressure in the cold isostatic pressing step is 50-200 MPa, and the time is 3-20 min.

5. The method according to any of claims 2-4, characterized by: In the step 3), the material constituting the can is stainless steel or carbon steel.

6. The method of any one of claims 2-5, wherein: The temperature of the vacuum heat deaeration in the step 3) is 500-900℃; the vacuum degree is at least 2E -3 Pa; the holding time is 5-10h.

7. The method of any one of claims 2-6, wherein: In the step 4), the temperature in the hot isostatic pressing step is 1000-1300 ℃, the pressure is 100-150 MPa, and the holding time is 60-240 min.

8. The method of any one of claims 2-7, wherein: In the step 5), the high-temperature treatment temperature is 1400 ℃-1800 ℃, and the holding time is 60-180 min.

9. The method of any one of claims 2-8, wherein: The high-temperature treatment in the step 5) is performed in a high-temperature furnace, and the furnace atmosphere is a vacuum atmosphere, an argon atmosphere, or a flowing hydrogen atmosphere. 10.Use of the single tungsten-rich phase tungsten-titanium alloy of claim 1 as a target material.

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