阅读说明：本技术 一种高塑性非均匀异质结构钨的制备方法 (Preparation method of high-plasticity heterogeneous heterostructure tungsten ) 是由 聂志华 宁浩森 谭成文 于晓东 宁先进 赵修臣 于 2020-11-13 设计创作，主要内容包括：本发明涉及一种高塑性非均匀异质结构钨的制备方法,属于金属钨制备技术领域。先采用化学气相沉积方法制备柱状晶组织的钨板,然后通过热轧制变形处理得到纤维状变形组织的钨板,最后通过部分再结晶退火热处理得到由纤维状变形组织与部分再结晶等轴组织共同构成的高塑性非均匀异质结构钨。与传统制备的均质结构钨相比,本发明所制备的非均匀异质结构钨的断裂方式路径发生改变,偏转角度增加,从而提高其断裂所需要的功,进而能够提高非均匀异质结构钨的塑性。本发明所述方法操作简单,可以有效提高钨的塑性,有利于扩大钨的应用范围,具有很好的应用前景。(The invention relates to a preparation method of high-plasticity heterogeneous heterostructure tungsten, and belongs to the technical field of metal tungsten preparation. Firstly, preparing a tungsten plate with a columnar crystal structure by adopting a chemical vapor deposition method, then obtaining the tungsten plate with a fibrous deformation structure by hot rolling deformation treatment, and finally obtaining high-plasticity heterogeneous structure tungsten jointly consisting of the fibrous deformation structure and a part of recrystallized equiaxial structure by partial recrystallization annealing heat treatment. Compared with the traditional prepared tungsten with the homogeneous structure, the tungsten with the heterogeneous structure prepared by the invention has the advantages that the fracture mode and path are changed, and the deflection angle is increased, so that the work required by the fracture of the tungsten is improved, and the plasticity of the tungsten with the heterogeneous structure can be improved. The method disclosed by the invention is simple to operate, can effectively improve the plasticity of tungsten, is beneficial to expanding the application range of tungsten, and has a good application prospect.)

1. A preparation method of high-plasticity heterogeneous heterostructure tungsten is characterized by comprising the following steps: the steps of the method are as follows,

(1) reducing tungsten hexafluoride by using hydrogen, performing chemical vapor deposition of polycrystalline tungsten on the substrate, and forming a tungsten plate with the thickness of more than 10mm and a columnar crystal structure along the deposition direction on the substrate;

(2) carrying out hot rolling deformation treatment on the tungsten plate obtained in the step (1), wherein the deformation temperature is 1400-1500 ℃, and the total deformation is 50-70%, so as to obtain a fibrous tungsten plate with a homogeneous deformation structure along the rolling direction;

(3) and (3) carrying out vacuum annealing heat treatment on the tungsten plate obtained in the step (2), wherein the annealing heat treatment temperature is 1500-1800 ℃, and the annealing heat treatment time is 1-4 h, so that the high-plasticity heterogeneous heterostructure tungsten jointly formed by the fibrous deformed structure and the recrystallized isometric structure is obtained.

2. The method for preparing the high-plasticity heterogeneous heterostructure tungsten according to claim 1, wherein the method comprises the following steps: in the step (1), the chemical vapor deposition of the polycrystalline tungsten is carried out under normal pressure and at the temperature of 500-600 ℃, and the deposition rate is 0.2-0.4 mm/h.

3. The method for preparing the high-plasticity heterogeneous heterostructure tungsten according to claim 1, wherein the method comprises the following steps: in the step (1), the thickness of the prepared tungsten plate with the columnar crystal structure is 10-30 mm.

4. The method for preparing the high-plasticity heterogeneous heterostructure tungsten according to claim 1, wherein the method comprises the following steps: in the step (2), the tungsten plate obtained in the step (1) is subjected to 3-4 times of hot rolling deformation treatment.

5. The method for preparing high-plasticity heterogeneous heterostructure tungsten according to claim 4, wherein the method comprises the following steps: in the step (2), when the tungsten plate obtained in the step (1) is subjected to 3-4 times of hot rolling deformation treatment, the reduction per time is 20-30%.

6. The method for preparing the high-plasticity heterogeneous heterostructure tungsten according to claim 1, wherein the method comprises the following steps: in the step (3), the annealing heat treatment temperature is 1500-1800 ℃, and the annealing heat treatment time is (120 +/-30) min.

Technical Field

The invention relates to a preparation method of high-plasticity heterogeneous heterostructure tungsten, and belongs to the technical field of metal tungsten preparation.

Background

Nuclear fusion, as a clean energy source, is now an important part of the sustainable development of energy in the world in the future. In the development of nuclear fusion technology, plasma-oriented materials are the main material problem facing fusion reactors. The service environment of the plasma-oriented material is very severe, and the material needs to receive high temperature and high thermal impact and is subjected to direct erosion and sputter corrosion of plasma, neutron irradiation impact and the like. Tungsten as a high atomic number material has the advantages of highest melting point, no tritium codeposition, no chemical etching, high-temperature strength and the like, has high plasma scouring resistance, and is a most promising plasma-oriented material. However, tungsten belongs to an intrinsic brittle material, the ductile-brittle transition temperature is high, and the recrystallization of tungsten can raise the ductile-brittle transition temperature point, so that recrystallization embrittlement is caused. Therefore, if tungsten is applied to the first wall material of the nuclear fusion device, the brittleness problem faced by tungsten needs to be solved.

The deformation strengthening is the main way to improve the performance of the metal at present, because the deformation strengthening can change the number, distribution and structure of defective tissues in the metal, thereby improving the performance of the material. Rolling is one way of obtaining a deformation strengthening of a metal sheet. The rotation and movement of the grain boundary can occur in the rolling process, along with the increase of the deformation, the deformation of the crystal grains is also enhanced, the structure is gradually distributed in a fibrous shape, and a sub-crystal structure appears in the crystal grains, and the performance of the material can be obviously improved due to the formation of the deformation structure.

The traditional equiaxial homogeneous powder metallurgy tungsten is usually used for improving the performance by deformation strengthening, but the tungsten is recrystallized to generate new undistorted crystal grains under high-temperature service, and the recrystallization phenomenon can cause the plasticity of the material to be rapidly reduced, so that the tungsten is easy to break under the service condition. The recrystallization temperature of the powder metallurgy tungsten is 1300-1400 ℃, so the service range of the powder metallurgy tungsten is required to be less than 1400 ℃. The recrystallization temperature of the chemical vapor deposition columnar crystal tungsten is more than 1500 ℃, and the service range of the columnar crystal tungsten is wider than that of powder metallurgy tungsten. However, chemical vapor deposition tungsten is also affected by brittleness, deformation strengthening and recrystallization phenomena affect plasticity of the tungsten, and the service feasibility and service life of the tungsten under the target environment service condition are affected. Therefore, the comprehensive evaluation of the deformation strengthening and recrystallization behaviors and the corresponding tissue regulation and control behaviors plays an extremely important role in the influence of the chemical vapor deposition tungsten plasticity.

Disclosure of Invention

In view of the above, the invention provides a method for preparing high-plasticity tungsten with a non-uniform heterostructure, which comprises the steps of preparing tungsten by a chemical vapor deposition process, and performing hot rolling deformation and partial recrystallization annealing treatment on the tungsten to realize regulation and control of a tungsten tissue structure, change a crack propagation path when a tungsten material is fractured, and increase energy required by the fracture, thereby obtaining the high-plasticity tungsten with the non-uniform heterostructure.

The purpose of the invention is realized by the following technical scheme.

A preparation method of high-plasticity heterogeneous heterostructure tungsten comprises the following steps:

(1) tungsten plate prepared by chemical vapor deposition

Reducing tungsten hexafluoride by using hydrogen, performing chemical vapor deposition of polycrystalline tungsten on the substrate, and forming a tungsten plate with the thickness of more than 10mm and a columnar crystal structure along the deposition direction on the substrate;

further, it is preferable to carry out chemical vapor deposition of polycrystalline tungsten at normal pressure (101kPa) and at a temperature of 500 to 600 ℃ at a deposition rate of 0.2 to 0.4 mm/h;

further, the thickness of the tungsten plate is preferably 10mm to 30 mm;

(2) hot rolling deformation

Carrying out hot rolling deformation treatment on the tungsten plate obtained in the step (1), wherein the deformation temperature is 1400-1500 ℃, the total deformation is 50% -70%, and the columnar structure of the tungsten plate is regulated into a fibrous structure through hot rolling deformation, so that the tungsten plate with a fibrous homogeneous deformation structure along the rolling direction is obtained;

further, carrying out 3-4 times of hot rolling deformation treatment on the tungsten plate, wherein the reduction of each time is preferably 20-30%;

(3) annealing heat treatment for partial recrystallization

And (3) carrying out vacuum annealing heat treatment on the tungsten plate obtained in the step (2), wherein the annealing heat treatment temperature is 1500-1800 ℃, the annealing heat treatment time is 1-4 h, partial recrystallization of tungsten occurs in the annealing heat treatment process, and partial fibrous deformation tissue evolves into fine equiaxed grains, so that the high-plasticity heterogeneous structure tungsten consisting of the fibrous deformation tissue and the partial recrystallization equiaxed tissue is obtained.

Further, the time of the annealing heat treatment at 1500 to 1800 ℃ is preferably (120. + -. 30) min.

Has the advantages that:

according to the invention, the chemical vapor deposition tungsten is treated by adopting a hot rolling deformation and partial recrystallization annealing heat treatment process under specific conditions, the structure of the tungsten can be regulated and controlled into a heterogeneous structure which is formed by fibrous deformation structures and recrystallized equiaxial structures together, compared with the traditional prepared homogeneous structure tungsten, the fracture mode path of the heterogeneous structure tungsten is changed, the deflection angle is increased, and the work required by the fracture of the heterogeneous structure tungsten is improved, so that the plasticity of the heterogeneous structure tungsten is greater than that of the homogeneous structure tungsten. The method provided by the invention is simple to operate, can effectively improve the plasticity of tungsten, and is beneficial to expanding the application range of tungsten.

Drawings

Fig. 1 is a graph comparing the stress-strain curves of the non-uniform heterostructure tungsten and the uniform heterostructure tungsten of example 1.

FIG. 2 is a diagram showing the three-point bending crack propagation path of tungsten in the homogeneous structure of example 1.

FIG. 3 is a graph of the tungsten three-point bending crack propagation path of the heterogeneous structure of example 1.

FIG. 4 is a simplified fracture model diagram of heterogeneous and homogeneous tungsten.

Detailed Description

The present invention is further illustrated by the following detailed description, wherein the processes are conventional unless otherwise specified, and the starting materials are commercially available from a public source without further specification.

Example 1

(1) Tungsten plate prepared by chemical vapor deposition

Reducing tungsten hexafluoride by using hydrogen under the pressure of 101kPa and the temperature of 550 ℃, carrying out chemical vapor deposition of polycrystalline tungsten on a copper substrate at the deposition rate of 0.3mm/h, and forming a tungsten plate with the thickness of 15mm and a columnar crystal structure along the deposition direction on the copper substrate;

(2) hot rolling deformation

Carrying out hot rolling deformation treatment on the tungsten plate obtained in the step (1) for 3 times, wherein the reduction of each pass is 20-25%, the total deformation is 60%, the deformation temperature is 1500 ℃, and the columnar structure of the tungsten plate is regulated into a fibrous structure through hot rolling deformation, so that the tungsten plate with a fibrous homogeneous deformation structure along the rolling direction is obtained, and the tungsten at the moment is abbreviated as homogeneous structure tungsten;

(3) annealing heat treatment for partial recrystallization

And (3) carrying out vacuum annealing heat treatment on the tungsten plate obtained in the step (2), wherein the annealing heat treatment temperature is 1500 ℃, the annealing heat treatment time is 2 hours, partial recrystallization phenomenon of tungsten occurs in the annealing heat treatment process, and partial fibrous deformation structure evolves into fine isometric grains, so that the high-plasticity heterogeneous heterostructure tungsten formed by the fibrous deformation structure and the partial recrystallization isometric structure is obtained.

And respectively carrying out three-point bending test at 250 ℃ on the prepared tungsten with the non-uniform heterostructure and the tungsten with the uniform heterostructure to obtain a stress-strain curve diagram as shown in the figure. As can be seen from the test results of fig. 1, the strain of the homogeneous structure tungsten is 12%, and the strain of the heterogeneous heterostructure tungsten in the 1500 ℃ annealed state is 18%. It can be seen that the heterogeneous heterostructure tungsten in the 1500 ℃ annealed state is more plastic than the homogeneous structure tungsten in the rolled state.

For the fracture of tungsten in the homogeneous deformation structure, the crack is a transgranular fracture propagation and vertically passes through the homogeneous deformation structure, as shown in fig. 2; in contrast, for heterogeneous heterostructure tungsten fracture, crack propagation is divided into transgranular fracture and intergranular fracture, exhibiting transgranular fracture when propagating to deformed structure and exhibiting intergranular fracture when propagating to recrystallized equiaxed structure, as shown in fig. 3.

The simplified fracture models of the heterogeneous tungsten and the homogeneous tungsten are shown in fig. 4, the total fracture power can be calculated from the homogeneous tungsten crack propagation model as the transgranular fracture power, and the total fracture power can be calculated from the heterogeneous tungsten crack propagation model as the transgranular fracture power plus another part of the intergranular fracture power which is constantly greater than the power required for the homogeneous structure to fracture. The energy required to fracture the heterogeneous heterostructure tungsten is therefore greater than that of the homogeneous structure tungsten. At the same time, the deflection angle of the main crack influences the plasticity of the material, whereas the deflection angle is related to the microstructure distribution of the inhomogeneous microstructure of the material.

From the above, the heterogeneous tungsten composed of the fibrous deformed structure and the partially recrystallized equiaxial structure prepared in this embodiment can improve the energy required for fracture by changing the fracture mode and path in the service state and increasing the deflection angle, so as to improve the plasticity of the chemical vapor deposition tungsten, and further improve the service capability of the chemical vapor deposition tungsten.

Example 2

(1) Tungsten plate prepared by chemical vapor deposition

Reducing tungsten hexafluoride by using hydrogen under the pressure of 101kPa and the temperature of 550 ℃, carrying out chemical vapor deposition of polycrystalline tungsten on a copper substrate at the deposition rate of 0.3mm/h, and forming a tungsten plate with the thickness of 15mm and a columnar crystal structure along the deposition direction on the copper substrate;

(2) hot rolling deformation

Carrying out hot rolling deformation treatment on the tungsten plate obtained in the step (1) for 3 times, wherein the reduction of each pass is 25-30%, the total deformation is 70%, the deformation temperature is 1650 ℃, and the columnar structure of the tungsten plate is regulated into a fibrous structure through hot rolling deformation, so that the tungsten plate with a fibrous homogeneous deformation structure along the rolling direction is obtained, and the tungsten at the moment is abbreviated as homogeneous structure tungsten;

(3) annealing heat treatment for partial recrystallization

And (3) carrying out vacuum annealing heat treatment on the tungsten plate obtained in the step (2), wherein the annealing heat treatment temperature is 1800 ℃, the annealing heat treatment time is 2 hours, partial recrystallization phenomenon of tungsten occurs in the annealing heat treatment process, and partial fibrous deformation structure evolves into fine isometric grains, so that the high-plasticity heterogeneous heterostructure tungsten formed by the fibrous deformation structure and the partial recrystallization isometric structure is obtained.

And respectively carrying out three-point bending test at 250 ℃ on the tungsten with the non-uniform heterostructure and the tungsten with the homogeneous structure, wherein the strain of the tungsten with the homogeneous structure is 4%, and the strain of the tungsten with the non-uniform heterostructure in an annealing state at 1800 ℃ is 9%. It can be seen that the plasticity of the heterogeneous heterostructure tungsten in the 1800 ℃ annealed state is significantly better than that of the homogeneous tungsten in the rolled state.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.