Ultrafine-grain high-purity tantalum target blank and preparation method thereof

Abstract

The invention relates to the technical field of high-purity metal sputtering target materials, in particular to an ultra-fine grain high-purity tantalum target blank and a preparation method thereof. The preparation method of the ultra-fine grain high-purity tantalum target blank comprises the following steps that an extrusion die with a gradient die hole length-diameter ratio is adopted for conducting a multi-round extrusion process on a high-purity tantalum cast ingot, the high-purity tantalum cast ingot obtained after each round of extrusion is subjected to vacuum annealing, and the high-purity tantalum target blank is obtained; carrying out a cold rolling process on the high-purity tantalum target blank; and carrying out vacuum graded annealing on the tantalum blank subjected to the cold rolling process. According to the preparation method of the ultra-fine grain high-purity tantalum target blank, through precise cooperation of a series of innovative processes, the ultra-fine grain high-purity tantalum target blank which is finer and even in distribution compared with a conventional process is obtained.

Description

Technical Field

[0001] This invention relates to the field of high-purity metal sputtering target technology, and in particular to an ultrafine-grained high-purity tantalum target blank and its preparation method. Background Technology

[0002] High-purity tantalum (Ta) sputtering targets are key materials in semiconductor integrated circuit manufacturing. Their microstructure and purity directly determine the quality of the sputtered thin film, which in turn affects the chip's performance and yield. With the development of advanced integrated circuit manufacturing processes, the demand for high-purity tantalum sputtering targets with finer grains and more precise orientation control is becoming increasingly urgent.

[0003] Currently, the traditional process for preparing tantalum target blanks in the industry mostly adopts a combination of forging and rolling. However, this method has inherent bottlenecks in grain refinement and orientation control, making it difficult to obtain an ideal ultrafine grain structure, and it is easy to generate uneven textured stripes in the core of the material, which deteriorates the film uniformity during the sputtering process.

[0004] To overcome the aforementioned drawbacks, extrusion technology is considered a highly promising alternative. By applying strong shear stress during extrusion, the original coarse grains of the ingot can be effectively broken, promoting recrystallization of the target billet and thus obtaining a finer, more uniform microstructure, with the potential to improve texture distribution. This ultrafine-grained high-purity tantalum target material prepared by extrusion is an ideal choice to meet the needs of advanced integrated circuits, such as the fabrication of diffusion barrier layers.

[0005] Despite the promising future of extrusion technology, directly applying existing technologies to the processing of high-purity tantalum faces significant challenges. For example, Chinese patent CN114589212A discloses a hot extrusion process for ultra-high purity copper targets, which utilizes a specific die to achieve one-time hot extrusion forming, producing copper billets with uniform grains. However, this approach cannot be directly applied to tantalum production due to the significant differences in material properties: copper is a face-centered cubic (FCC) metal with good plasticity and easy deformation; while tantalum is a body-centered cubic (BCC) metal with a significantly fewer slip systems, resulting in poor plastic deformation capacity and high deformation resistance. Using conventional single-extrusion processes can easily lead to billet cracking and failure.

[0006] Therefore, developing a dedicated extrusion tool and matching processing technology to effectively refine grains and control microstructure, taking into account the physical properties of high-purity tantalum, a difficult-to-deform metal, is a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0007] This invention provides an ultrafine-grained high-purity tantalum target blank and its preparation method, which solves the problem that existing high-purity tantalum target blank preparation methods are difficult to achieve effective grain refinement and microstructure control.

[0008] According to a first aspect of the present invention, the present invention provides a method for preparing an ultrafine-grained high-purity tantalum target blank, comprising the following steps: A multi-round extrusion process is performed on the high-purity tantalum ingot using an extrusion die with a gradient die length-to-diameter ratio, and the high-purity tantalum ingot after each round of extrusion is vacuum annealed to obtain a high-purity tantalum target billet. The high-purity tantalum target billet is subjected to a cold rolling process; The tantalum billet after cold rolling is subjected to vacuum graded annealing to obtain an ultrafine-grained high-purity tantalum target billet.

[0009] The method for preparing ultrafine-grained high-purity tantalum target billets provided by this invention first utilizes extrusion with a gradient die aspect ratio followed by inter-cycle annealing to effectively break down the coarse as-cast structure and restore the material's plasticity. Simultaneously, the shear stress during the extrusion process can effectively reduce the core {110}. <uvw>The formation of texture lays a uniform microstructure foundation for subsequent processing. The cold rolling process introduces and stores a large amount of uniformly distributed distortion energy within the material, which provides a strong driving force for the final recrystallization. Then, vacuum graded annealing is used to precisely separate the nucleation and growth processes, achieving explosive nucleation at low temperatures and rapid recrystallization at high temperatures while effectively suppressing grain growth. The preparation method of this invention has precise coordination between the steps, thereby stably obtaining ultrafine-grained high-purity tantalum target blanks with grain sizes much smaller than those of traditional processes and uniform and controllable microstructure, which significantly improves the sputtering rate and service life of the target material.

[0010] According to the preparation method of ultrafine-grained high-purity tantalum target blank of the present invention, the extrusion die includes a main extrusion channel and multiple sub-extrusion channels. The sub-extrusion channels are connected to the main extrusion channel. An extrusion inlet is provided on the sub-extrusion channel, and an extrusion outlet is provided on the main extrusion channel. The sub-extrusion channel is zigzag-shaped and includes a first extrusion section and a second extrusion section connected to each other. The included angle α between the first extrusion section and the main extrusion channel is 120°-150°, and the included angle β between the first extrusion section and the second extrusion section is 120°-150°.

[0011] This invention, by setting multiple zigzag-shaped sub-extrusion channels that ultimately converge into the main extrusion channel, forces high-purity tantalum ingots to undergo multiple, non-collinear, and intense shear deformations during the extrusion process. Each 120°-150° turning angle (α and β) applies enormous shear plastic strain to the material. This strong shear plastic deformation mechanism can more efficiently and uniformly break down the coarse original as-cast structure and reduce the core {110} compared to traditional linear extrusion. <uvw>The texture formation ultimately results in significant grain refinement and precise microstructure control during the extrusion stage, laying a superior microstructure foundation for subsequent cold working and heat treatment to obtain the final ultrafine grain structure.

[0012] Preferably, the high-purity tantalum ingot is rotated 40°-50° after each extrusion through a different extrusion inlet. This operation ensures that each extrusion processes the material on a completely new shear plane, thereby avoiding fibrous structures and strong textures caused by unidirectional shear deformation. This results in a more uniform strain distribution throughout the ingot volume and more thorough grain breakage and refinement.

[0013] Preferably, the extrusion speed is 0.3~0.8 mm / s. This speed avoids the drastic "adiabatic temperature rise" caused by excessively fast extrusion, thereby effectively preventing thermal cracks caused by local overheating inside the material; on the other hand, it also ensures that the material has enough time for plastic flow, avoiding a sharp increase in deformation resistance due to excessively rapid cooling.

[0014] According to the method for preparing ultrafine-grained high-purity tantalum target billets of the present invention, each extrusion round involves sequentially passing the high-purity tantalum ingot through extrusion inlets with progressively decreasing die length-to-diameter ratios. This achieves gradient-type strong plastic deformation.

[0015] In the initial extrusion process, the large aspect ratio applies extremely high hydrostatic pressure, providing strong constraint and effectively suppressing the cracking tendency of coarse as-cast structures in the early stages of severe deformation, forcibly breaking them down. In subsequent extrusion processes, the gradually decreasing aspect ratio reduces extrusion resistance and frictional work, allowing energy to be more efficiently concentrated on grain refinement within the material, rather than being consumed in overcoming friction. This gradient process design, characterized by "forced extrusion followed by high efficiency," ensures safe, efficient, and more thorough microstructure control and grain refinement throughout the entire extrusion process.

[0016] Preferably, the length-to-diameter ratio of the die hole decreases sequentially from (3-5):1 to (1-2):1.

[0017] In some specific embodiments, the length-to-diameter ratio of the die holes decreases sequentially from 4:1 to 2:1.

[0018] According to the preparation method of the ultrafine-grained high-purity tantalum target billet of the present invention, the vacuum degree of vacuum annealing of the high-purity tantalum ingot after each round of extrusion is ≤1×10⁻⁶. -3 Pa (preferably 1×10) -3 Pa ~ 1×10 -4 The annealing temperature is 900-1000℃, and the holding time is 60-120 min. After annealing, the temperature is forcibly cooled to room temperature with argon gas.

[0019] The vacuum annealing process between these rounds, through precise parameter control, plays a crucial role in bridging the gap between the previous and subsequent extrusion processes. Firstly, the temperature of 900-1000℃ and the holding time of 60-120 minutes aim to completely eliminate the severe work hardening and internal stress introduced by the previous round of intense plastic deformation, restoring the material's plasticity through recrystallization and preparing it for successful extrusion in the next round. Secondly, ≤1×10 -3 Pa's high vacuum effectively prevents high-purity tantalum from being oxidized or contaminated at high temperatures, thus maintaining its inherent high purity. Argon forced cooling allows the tantalum billet to pass quickly through the high-temperature zone where grain growth is likely to occur, thereby "freezing" and preserving the fine, uniform equiaxed crystal structure formed after recrystallization. This avoids the grain coarsening that may be caused by traditional slow cooling, providing an excellent initial structure for finally obtaining the ultrafine grain target.

[0020] According to the preparation method of the ultrafine-grained high-purity tantalum target blank of the present invention, the high-purity tantalum target blank undergoing annealing is subjected to a 10-15 pass cold rolling process, controlling the deformation amount of each pass to 5-10%, and the total deformation amount to 80-90%. This further elongates the equiaxed crystals formed by extrusion into a flat and elongated rolled structure, increases the grain boundary area, and introduces rolling texture.

[0021] According to the preparation method of ultrafine-grained high-purity tantalum target blank of the present invention, the tantalum blank after cold rolling process is subjected to vacuum graded annealing as follows: first stage annealing: temperature 600-800℃, holding temperature 20-40min; second stage annealing: temperature 1000-1100℃, holding temperature 20-40min.

[0022] The first stage of annealing can eliminate rolling stress and reduce deformation storage energy, while the second stage of annealing can inhibit grain coarsening and promote uniform microstructure.

[0023] After staged annealing, the target billet is forced to cool to room temperature with argon gas. The grain size can be controlled below 15 μm, and the grain distribution is uniform with no abnormal coarse grains and the {111} are effectively controlled. <uvw> 、{110} <uvw>Texture proportion.

[0024] According to the preparation method of the ultrafine-grained high-purity tantalum target blank of the present invention, the purity of the high-purity tantalum ingot is ≥99.999%.

[0025] Preferably, the high-purity tantalum ingot with a purity of ≥99.999% is obtained by purifying the tantalum ingot with a purity of ≥99.99% through electron beam melting; more preferably, the electron beam melting speed is 20-40 kg / h, the melting power is 1000-1500 KW, and the number of melting times is 2-3.

[0026] According to the method for preparing ultrafine-grained high-purity tantalum target blanks of the present invention, before performing a multi-round extrusion process on the high-purity tantalum ingot using an extrusion die with a gradient die aspect ratio, the high-purity tantalum ingot is preheated to 200°C to 300°C in an argon atmosphere. This preheating step can significantly improve the initial plasticity of the high-purity tantalum ingot before entering the extrusion die and reduce its deformation resistance.

[0027] This invention heats the ingot to a warm processing range of 200°C to 300°C, which can effectively avoid the risk of surface cracking or internal fracture due to insufficient toughness when the material comes into contact with the mold in a cold state and is subjected to huge initial stress. This ensures that the subsequent strong plastic deformation process can start smoothly. At the same time, the protective effect of the argon atmosphere prevents oxidation during the preheating process and maintains the high purity of the material.

[0028] According to a second aspect of the present invention, the present invention also provides an ultrafine-grained high-purity tantalum target blank, which is prepared by the above-described method for preparing an ultrafine-grained high-purity tantalum target blank; the average grain size of the ultrafine-grained high-purity tantalum target blank is ≤15μm (preferably 5μm-10μm), {111} <uvw>Percentage ≤30% (preferably 20%-25%), {110} <uvw>The proportion is ≤10% (preferably 4%-8%).

[0029] The beneficial effects of this invention are: This invention, through the precise synergy of a series of innovative processes, firstly utilizes a specific extrusion die combined with multi-axial shear deformation and annealing to efficiently and uniformly refine the coarse as-cast microstructure, laying a superior microstructure foundation for subsequent processing that is unmatched by traditional methods. Building upon this, a large recrystallization driving force is stored through high total deformation cold rolling, and then the core vacuum staged annealing process cleverly decouples the nucleation and growth processes, ultimately yielding an ultrafine-grained microstructure that is far finer and more uniformly distributed than that obtained through conventional processes. This superior microstructure ultimately endows the target blank with significantly improved end-use performance, manifesting in sputtering applications as higher sputtering rates, better film uniformity, and higher target utilization and longer service life due to weakened texture, demonstrating extremely high industrial application value. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the extrusion die used in the preparation method of the ultrafine-grained high-purity tantalum target blank provided in Embodiment 1 of the present invention.

[0032] Reference numerals: 1: Main extrusion channel; 10: Extrusion outlet; 2: Sub-extrusion channel; 21: First extrusion section; 22: Second extrusion section; 201: First extrusion inlet; 202: Second extrusion inlet; 203: Third extrusion inlet; 204: Fourth extrusion inlet; 3: Extrusion head; 4: High-purity tantalum ingot. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] Example 1 This embodiment provides a method for preparing an ultrafine-grained high-purity tantalum target blank, comprising the following steps: (1) The 4N high-purity tantalum ingot was first purified by electron beam melting furnace. The melting speed was 30kg / h and the melting power was controlled at 1200KW. The melting was carried out twice. After melting, the purity of the tantalum ingot was 5N5.

[0035] (2) The high-purity tantalum ingot is preheated to 200℃. The high-purity tantalum ingot is subjected to a two-round extrusion process in an argon atmosphere using an extrusion die with a gradient die length-to-diameter ratio.

[0036] like Figure 1 As shown, the extrusion die includes a main extrusion channel 1 and four sub-extrusion channels 2. The sub-extrusion channels 2 are connected to the main extrusion channel 1. Each sub-extrusion channel 2 is provided with an extrusion inlet 20 (first extrusion inlet 201, second extrusion inlet 202, third extrusion inlet 203, and fourth extrusion inlet 204). The main extrusion channel 1 is provided with an extrusion outlet 10. The sub-extrusion channels are zigzag-shaped and include a first extrusion section 21 and a second extrusion section 22 that are connected. The included angle β between the first extrusion section 21 and the second extrusion section 22 is 150°, and the included angle α between the first extrusion section 21 and the main extrusion channel 1 is 150°. The extrusion inlets 20 include the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204. The length-to-diameter ratios of the die orifices of the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 are 4:1, 3.5:1, 3:1, and 2:1, respectively.

[0037] Each extrusion cycle involves passing the high-purity tantalum ingot 4 sequentially through the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 via the extrusion head 3. After each extrusion through different inlets 20, the high-purity tantalum ingot is rotated 45°, subjecting it to large composite shear deformation within the double-angle extrusion process. This effectively breaks down the original cast grains and eliminates defects such as shrinkage cavities and porosity within the ingot. The extrusion speed is controlled at 0.3 mm / s.

[0038] (3) Vacuum annealing (vacuum degree ≤ 1×10) is performed on the tantalum ingots obtained by extrusion in step (2) after each round of extrusion. - 3 (Pa), annealing temperature 900℃, hold for 120 min, and then forced cooling to room temperature with argon gas after annealing.

[0039] (4) The tantalum target blank obtained in step (3) is subjected to a 15-pass cold rolling process, with the deformation amount controlled at 5% per pass and the total deformation amount at 80%.

[0040] (5) The rolled tantalum billet is subjected to vacuum graded annealing. First stage annealing: temperature 600℃, holding for 20min, to eliminate rolling stress and release deformation stored energy; Second stage annealing: temperature 1100℃, holding for 20min, and after holding, forced cooling to room temperature with argon gas is used.

[0041] The microstructure of the obtained high-purity tantalum target blank is shown in Table 1. The average grain size is 10 μm, {111} <uvw>The percentage was 24.6%, {110} <uvw>It accounted for 5.2%.

[0042] Example 2 This embodiment provides a method for preparing an ultrafine-grained high-purity tantalum target blank, comprising the following steps: (1) The 4N high-purity tantalum ingot was first purified by electron beam melting furnace. The melting speed was 30kg / h and the melting power was controlled at 1200KW. The melting was carried out twice. After melting, the purity of the tantalum ingot was 5N5.

[0043] (2) The high-purity tantalum ingot is preheated to 300℃. The high-purity tantalum ingot is then subjected to a two-stage extrusion process using an extrusion die with a gradient die length-to-diameter ratio under an argon atmosphere.

[0044] like Figure 1 As shown, the extrusion die includes a main extrusion channel 1 and four sub-extrusion channels 2. The sub-extrusion channels 2 are connected to the main extrusion channel 1. Each sub-extrusion channel 2 is provided with an extrusion inlet 20 (first extrusion inlet 201, second extrusion inlet 202, third extrusion inlet 203, and fourth extrusion inlet 204). The main extrusion channel 1 is provided with an extrusion outlet 10. The sub-extrusion channels are zigzag-shaped and include a first extrusion section 21 and a second extrusion section 22 that are connected. The included angle β between the first extrusion section 21 and the second extrusion section 22 is 120°, and the included angle α between the first extrusion section 21 and the main extrusion channel 1 is 120°. The extrusion inlets 20 include the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204. The length-to-diameter ratios of the die orifices of the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 are 5:1, 4:1, 3:1, and 2:1, respectively.

[0045] Each extrusion cycle involves passing the high-purity tantalum ingot 4 sequentially through the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 via the extrusion head 3. After each extrusion through different inlets 20, the high-purity tantalum ingot is rotated 45°, subjecting it to large composite shear deformation within the double-angle extrusion process. This effectively breaks down the original cast grains and eliminates internal defects such as shrinkage cavities and porosity. The extrusion speed is controlled at 0.8 mm / s.

[0046] (3) Vacuum annealing (vacuum degree ≤ 1×10) is performed on the tantalum ingots obtained by extrusion in step (2) after each round of extrusion. - 3 (Pa), annealing temperature 900℃, hold for 60 min, and then forced cooling to room temperature with argon gas after annealing.

[0047] (4) The tantalum target blank obtained in step (3) is subjected to a 12-pass cold rolling process, with the deformation amount controlled at 8% per pass and the total deformation amount at 90%.

[0048] (5) The rolled tantalum billet is subjected to vacuum graded annealing. First stage annealing: temperature 600℃, holding for 20min, to eliminate rolling stress and release deformation stored energy; Second stage annealing: temperature 1000℃, holding for 20min, and after holding, forced cooling to room temperature with argon gas is used.

[0049] The microstructure of the obtained high-purity tantalum target blank is shown in Table 1. The average grain size is 6 μm, {111} <uvw>The percentage was 22.5%, {110} <uvw>It accounted for 4.7%.

[0050] This embodiment provides a method for preparing an ultrafine-grained high-purity tantalum target blank. The difference from Embodiment 1 is that the aspect ratio of the extrusion die orifice is set differently, the α and β angles of the die are different, and the extrusion speed is changed. It is confirmed that the extrusion die and extrusion parameters designed in this invention have universality for the preparation of ultrafine-grained high-purity tantalum targets.

[0051] Example 3 This embodiment provides a method for preparing an ultrafine-grained high-purity tantalum target blank, comprising the following steps: (1) The 4N high-purity tantalum ingot was first purified by electron beam melting furnace. The melting speed was 30kg / h and the melting power was controlled at 1200KW. The melting was carried out twice. After melting, the purity of the tantalum ingot was 5N5.

[0052] (2) The high-purity tantalum ingot is preheated to 200℃. The high-purity tantalum ingot is subjected to a two-round extrusion process in an argon atmosphere using an extrusion die with a gradient die length-to-diameter ratio.

[0053] like Figure 1 As shown, the extrusion die includes a main extrusion channel 1 and four sub-extrusion channels 2. The sub-extrusion channels 2 are connected to the main extrusion channel 1. Each sub-extrusion channel 2 is provided with an extrusion inlet 20 (first extrusion inlet 201, second extrusion inlet 202, third extrusion inlet 203, and fourth extrusion inlet 204). The main extrusion channel 1 is provided with an extrusion outlet 10. The sub-extrusion channels are zigzag-shaped and include a first extrusion section 21 and a second extrusion section 22 that are connected. The included angle β between the first extrusion section 21 and the second extrusion section 22 is 150°, and the included angle α between the first extrusion section 21 and the main extrusion channel 1 is 150°. The extrusion inlets 20 include the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204. The length-to-diameter ratios of the die orifices of the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 are 4:1, 3.5:1, 3:1, and 2:1, respectively.

[0054] Each extrusion cycle involves passing the high-purity tantalum ingot 4 sequentially through the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 via the extrusion head 3. After each extrusion through different inlets 20, the high-purity tantalum ingot is rotated 45°, subjecting it to large composite shear deformation within the double-angle extrusion process. This effectively breaks down the original cast grains and eliminates defects such as shrinkage cavities and porosity within the ingot. The extrusion speed is controlled at 0.3 mm / s.

[0055] (3) Vacuum annealing (vacuum degree ≤ 1×10) is performed on the tantalum ingots obtained by extrusion in step (2) after each round of extrusion. - 3 (Pa), annealing temperature 1000℃, holding temperature 120min, and then forced cooling to room temperature with argon gas after annealing.

[0056] (4) The tantalum target blank obtained in step (3) is subjected to a 10-pass cold rolling process, with the deformation amount controlled at 10% per pass and the total deformation amount at 90%.

[0057] (5) The rolled tantalum billet was subjected to vacuum staged annealing. First stage annealing: temperature 800℃, holding for 40 min, to eliminate rolling stress and release deformation stored energy; Second stage annealing: temperature 1100℃, holding for 40 min, and after holding, forced cooling to room temperature with argon gas. The microstructure of the obtained high-purity tantalum target billet is shown in Table 1. The average grain size is 8 μm, {111} <uvw>The percentage was 24.3%, {110} <uvw>The percentage was 5.0%.

[0058] This embodiment provides a method for preparing an ultrafine-grained high-purity tantalum target blank. The difference from Embodiment 1 is that the vacuum annealing parameters during cold rolling and processing are different, confirming that the vacuum heat treatment parameters designed in this invention have universal applicability to the preparation of ultrafine-grained high-purity tantalum targets.

[0059] Comparative Example 1 This embodiment provides a method for preparing an ultrafine-grained high-purity tantalum target blank, comprising the following steps: (1) The 4N high-purity tantalum ingot was first purified by electron beam melting furnace. The melting speed was 30kg / h and the melting power was controlled at 1200KW. The melting was carried out twice. After melting, the purity of the tantalum ingot was 5N5.

[0060] (2) The high-purity tantalum ingot is preheated to 200℃. The high-purity tantalum ingot is subjected to a two-round extrusion process in an argon atmosphere using an extrusion die with a gradient die length-to-diameter ratio.

[0061] like Figure 1 As shown, the extrusion die includes a main extrusion channel 1 and four sub-extrusion channels 2. The sub-extrusion channels 2 are connected to the main extrusion channel 1. Each sub-extrusion channel 2 is provided with an extrusion inlet 20 (first extrusion inlet 201, second extrusion inlet 202, third extrusion inlet 203, and fourth extrusion inlet 204). The main extrusion channel 1 is provided with an extrusion outlet 10. Only the angle α between the first extrusion section 21 and the main extrusion channel 1 is 150°, and the angle β between the first extrusion section 21 and the second extrusion section 22 is 180°. The extrusion inlets 20 include the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204. The length-to-diameter ratios of the die orifices of the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 are 4:1, 3.5:1, 3:1, and 2:1, respectively.

[0062] Each extrusion cycle involves passing the high-purity tantalum ingot 4 sequentially through the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 via the extrusion head 3. After each extrusion through different inlets 20, the high-purity tantalum ingot is rotated 45°, subjecting it to large composite shear deformation within the double-angle extrusion process. This effectively breaks down the original cast grains and eliminates defects such as shrinkage cavities and porosity within the ingot. The extrusion speed is controlled at 0.3 mm / s.

[0063] (3) Vacuum annealing (vacuum degree ≤ 1×10) is performed on the tantalum ingots obtained by extrusion in step (2) after each round of extrusion. - 3 (Pa), annealing temperature 900℃, hold for 120 min, and then forced cooling to room temperature with argon gas after annealing.

[0064] (4) The tantalum target blank obtained in step (3) is subjected to a 15-pass cold rolling process, with the deformation amount controlled at 5% per pass and the total deformation amount at 80%.

[0065] (5) The rolled tantalum billet is subjected to vacuum graded annealing. First stage annealing: temperature 600℃, holding for 20min, to eliminate rolling stress and release deformation stored energy; Second stage annealing: temperature 1100℃, holding for 20min, and after holding, forced cooling to room temperature with argon gas is used.

[0066] The microstructure of the obtained high-purity tantalum target blank is shown in Table 1. The average grain size is 46 μm, {111} <uvw>The proportion was 35.1%, {110} <uvw>The percentage was 11.5%.

[0067] Comparative Example 2 This embodiment provides a method for preparing an ultrafine-grained high-purity tantalum target blank, comprising the following steps: (1) The 4N high-purity tantalum ingot was first purified by electron beam melting furnace. The melting speed was 30kg / h and the melting power was controlled at 1200KW. The melting was carried out twice. After melting, the purity of the tantalum ingot was 5N5.

[0068] (2) The high-purity tantalum ingot is preheated to 200℃. The high-purity tantalum ingot is subjected to a two-round extrusion process in an argon atmosphere using an extrusion die with a gradient die length-to-diameter ratio.

[0069] like Figure 1 As shown, the extrusion die includes a main extrusion channel 1 and four sub-extrusion channels 2. The sub-extrusion channels 2 are connected to the main extrusion channel 1. Each sub-extrusion channel 2 is provided with an extrusion inlet 20 (first extrusion inlet 201, second extrusion inlet 202, third extrusion inlet 203, and fourth extrusion inlet 204). The main extrusion channel 1 is provided with an extrusion outlet 10. The sub-extrusion channels are zigzag-shaped and include a first extrusion section 21 and a second extrusion section 22 that are connected. The included angle β between the first extrusion section 21 and the second extrusion section 22 is 150°, and the included angle α between the first extrusion section 21 and the main extrusion channel 1 is 150°. The extrusion inlets 20 include the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204. The length-to-diameter ratios of the die orifices of the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 are 4:1, 3.5:1, 3:1, and 2:1, respectively.

[0070] Each extrusion cycle involves passing the high-purity tantalum ingot 4 sequentially through the first extrusion inlet 201, the second extrusion inlet 202, the third extrusion inlet 203, and the fourth extrusion inlet 204 via the extrusion head 3. After each extrusion through different inlets 20, the high-purity tantalum ingot is rotated 45°, subjecting it to large composite shear deformation within the double-angle extrusion process. This effectively breaks down the original cast grains and eliminates defects such as shrinkage cavities and porosity within the ingot. The extrusion speed is controlled at 0.3 mm / s.

[0071] (3) Vacuum annealing (vacuum degree ≤ 1×10) is performed on the tantalum ingots obtained by extrusion in step (2) after each round of extrusion. - 3 (Pa), annealing temperature 900℃, hold for 120 min, and then forced cooling to room temperature with argon gas after annealing.

[0072] (4) The tantalum target blank obtained in step (3) is subjected to a 15-pass cold rolling process, with the deformation amount controlled at 5% per pass and the total deformation amount at 80%.

[0073] (5) The rolled tantalum billet is not subjected to vacuum grading annealing. It is only annealed at 1100℃ for 40 minutes. After the holding time is completed, it is forced to cool to room temperature with argon gas.

[0074] The microstructure of the obtained high-purity tantalum target blank is shown in Table 1. The average grain size is 30 μm, {111} <uvw>The percentage was 29.0%, {110} <uvw>It accounted for 9.8%.

[0075] Table 1

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.< / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw> < / uvw>

Claims

1. A method for producing an ultrafine-grained high-purity tantalum target blank, characterized by, The method comprises the following steps: The high-purity tantalum ingot is subjected to multi-pass extrusion using an extrusion die with a gradient die hole length-diameter ratio, and the high-purity tantalum ingot after each pass of extrusion is subjected to vacuum annealing to obtain a high-purity tantalum target blank; The obtained high-purity tantalum target blank is subjected to cold rolling; The tantalum blank after the cold rolling is subjected to vacuum staged annealing to obtain an ultra-fine-grained high-purity tantalum target blank.

2. The method of producing an ultrafine-grained high-purity tantalum target blank according to claim 1, characterized in that, The extrusion die comprises a main extrusion channel and a plurality of sub-extrusion channels, the sub-extrusion channels are in communication with the main extrusion channel, the sub-extrusion channels are provided with extrusion inlets, and the main extrusion channel is provided with an extrusion outlet; the sub-extrusion channels are in the shape of a broken line and comprise a first extrusion part and a second extrusion part in communication, an included angle α between the first extrusion part and the main extrusion channel is 120°-150°, and an included angle β between the first extrusion part and the second extrusion part is 120°-150°.

3. The method of producing an ultrafine-grained high-purity tantalum target blank according to claim 2, characterized in that, The high-purity tantalum ingot is rotated by 40°-50° after being extruded through different extrusion inlets each time; Preferably, the extrusion speed is 0.3-0.8 mm / s.

4. The method of producing an ultrafine-grained high-purity tantalum target blank according to any one of claims 1 to 3, characterized in that, Each pass of extrusion is performed by sequentially passing the high-purity tantalum ingot through extrusion inlets with a sequentially decreasing die hole length-diameter ratio. Preferably, the die hole length-diameter ratio sequentially decreases from (3-5):1 to (1-2):

1.

5. The method of producing an ultrafine-grained high-purity tantalum target blank according to any one of claims 1 to 4, characterized in that, The vacuum degree of vacuum annealing of the high-purity tantalum ingot after each extrusion is ≤1×10 -3 Pa, the annealing temperature is 900-1000℃, the holding time is 60-120min, and the high-purity tantalum ingot is forcedly cooled to room temperature by argon after annealing.

6. The method of producing an ultrafine-grained high-purity tantalum target blank according to any one of claims 1 to 5, characterized in that, The high-purity tantalum target blank subjected to reannealing is subjected to cold rolling for 10-15 passes, with a deformation amount of 5-10% for each pass and a total deformation amount of 80-90%.

7. The method of producing an ultrafine-grained high-purity tantalum target blank according to any one of claims 1 to 6, characterized in that, The tantalum blank after the cold rolling is subjected to vacuum staged annealing as follows: first-stage annealing: temperature 600-800°C, holding for 20-40 min; second-stage annealing: temperature 1000-1100°C, holding for 20-40 min, and rapid cooling to room temperature using argon after the holding is completed.

8. The method of producing an ultrafine-grained high-purity tantalum target blank according to any one of claims 1 to 7, characterized in that, The purity of the high-purity tantalum ingot is ≥99.999%. Preferably, the high-purity tantalum ingot with a purity of ≥99.999% is obtained by electron beam melting of a tantalum ingot with a purity of ≥99.99%; more preferably, the speed of the electron beam melting is 20-40 kg / h, the melting power is 1000-1500 KW, and the number of melting times is 2-3.

9. The method of producing an ultrafine-grained high-purity tantalum target blank according to any one of claims 1 to 8, characterized in that, Before the high-purity tantalum ingot is subjected to multi-pass extrusion using an extrusion die with a gradient die hole length-diameter ratio, the high-purity tantalum ingot is preheated to 200°C-300°C in an argon atmosphere.

10. An ultrafine-grained high-purity tantalum target blank, characterized in that, The ultrafine-grain high-purity tantalum target blank is prepared by the method of any one of claims 1-9, and has an average grain size of ≤15 μm,{111} <uvw>≤ 30%, {110} <uvw>The proportion is ≤10%.< / uvw> < / uvw>

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