CN114351028B - One kind (FeVCrMn) x Ti y Low-activation high-entropy alloy and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of alloy strengthening and nuclear fusion low-activation structural materials, and particularly discloses a (FeVCrMn) _x Ti _y Low activation high entropy alloy and method of making the same (FeVCrMn) _x Ti _y In the chemical formula of the low-activation high-entropy alloy, x + y =100, x is more than or equal to 90, and y is less than or equal to 10. (FeVCrMn) _x Ti _y The low-activation high-entropy alloy is of a single-phase body-centered cubic BCC structure, and the grain size is less than or equal to 200 mu m. (FeVCrMn) _x Ti _y The hardness of the low-activation high-entropy alloy is more than or equal to 400HV, the elastic modulus is about 200GPa, the room-temperature yield strength is more than or equal to 700MPa, and the room-temperature tensile strength is more than or equal to 1200MPa. Of the invention (FeVCrMn) _x Ti _y The low-activation high-entropy alloy takes Fe, V, cr and Mn as main components with equal atomic ratio, takes Ti as an adjusting element, and adopts a strengthening method mainly based on solid solution strengthening to achieve high-strength mechanical properties.

Description

A kind of (FeVCrMn)xTiy low-activation high-entropy alloy and its preparation method

technical field

The invention belongs to the field of alloy strengthening and nuclear fusion low-activation structural materials, and specifically relates to a (FeVCrMn) _x Ti _y low-activation high-entropy alloy and a preparation method thereof.

Background technique

The service conditions of structural materials for nuclear fusion reactors are very harsh, requiring materials with excellent neutron radiation resistance and high-temperature mechanical properties, and the composition meets the requirements of low activation. The development of fusion reactor structural materials is one of the key factors affecting the design, construction and commercial use of fusion reactors. Traditional alloys are generally based on one or two alloying elements, and the required mechanical properties are achieved by adding trace amounts of other elements or supplemented by different processing techniques. Often due to the limitations of the characteristics of the main elements, it is impossible to further improve its mechanical properties.

High-entropy alloy is a new material design concept. Due to the different atomic sizes of different constituent elements, its lattice will be severely distorted, and the atoms are randomly distributed freely in the lattice, making high-entropy alloys more efficient than general alloys. Excellent mechanical properties, with a wide range of potential applications. The composition selection of high-entropy alloys is more flexible and can give full play to the characteristics of each principal element. Due to the high mixing entropy, the formation of intermetallic compounds in the material is suppressed, and a solid solution structure with a simple structure can be obtained.

Structural materials with radiation resistance, high temperature resistance and excellent mechanical properties are key materials for fusion reactors. The concept of high-entropy alloys for fusion reactors provides ideas for the development of new fusion materials. In the selection of alloying elements, it is necessary to meet the requirement of low activation.

Therefore, it is urgent to develop a low-activation high-entropy alloy as a new fusion material for nuclear fusion reactors.

Contents of the invention

The object of the present invention is to provide a kind of (FeVCrMn) _x Ti _y low-activation high-entropy alloy and preparation method thereof, with Fe, V, Cr, Mn as the main component of equiatomic ratio, Ti as adjustment element, adopt solid solution strengthening as The main strengthening method to achieve high-strength mechanical properties.

The technical solution for realizing the object of the present invention: a kind of (FeVCrMn) _x Ti _y low-activation high-entropy alloy, in the chemical formula of (FeVCrMn) _x Ti _y low-activation high-entropy alloy, x+y=100, x≥90, y≤10 .

The (FeVCrMn) _x Ti _y low-activation high-entropy alloy has a single-phase body-centered cubic BCC structure, and the grain size is ≤ 200 μm.

The (FeVCrMn) _x Ti _y low-activation high-entropy alloy has a hardness ≥ 400 HV, an elastic modulus of about 200 GPa, a yield strength at room temperature ≥ 700 MPa, and a tensile strength at room temperature ≥ 1200 MPa.

In the chemical formula of the (FeVCrMn) _x Ti _y low-activation high-entropy alloy, x=95 and y=5.

In the chemical formula of the (FeVCrMn) _x Ti _y low-activation high-entropy alloy, x=98 and y=2.

A method for preparing (FeVCrMn) _x Ti _y low-activation high-entropy alloy, said method comprising the following steps:

Step 1, according to the atomic percentage of each element, weigh the raw materials of Fe, V, Cr, Mn and Ti elemental elements, and put them into the water-cooled copper crucible of the vacuum arc melting furnace;

Step 2. Carry out vacuum arc melting to the raw materials of Fe, V, Cr, Mn and Ti elemental elements put into the water-cooled copper crucible of the vacuum arc melting furnace.

The step 2 is specifically: evacuate the vacuum chamber to ≤5×10 ^-3 Pa, then fill the high-purity argon until the pressure of the vacuum chamber is -0.8 to -0.6MPa, the melting current is 350-450A, and the melting current is 350-450A. Cooling water: Melt the front and back sides of the alloy ingot repeatedly for 3-5 times, each time for 3-6 minutes, and the alloy stays in the liquid state for a total of 10-30 minutes, and finally cool down to obtain (FeVCrMn) _x Ti _y low-activation high-entropy alloy ingot .

The beneficial technical effects of the present invention are:

1. The hardness of the (FeVCrMn) _x Ti _y low-activation high-entropy alloy of the present invention is ≥ 400HV, the elastic modulus is about 200GPa, the yield strength at room temperature is ≥ 700MPa, and the tensile strength at room temperature is ≥ 1200MPa. The strength of the low-activation high-entropy alloy is much higher Compared with the existing fusion reactor low-activation structural materials such as low-activation ferrite/martensitic steel and vanadium alloy, it is a new type of low-activation high-entropy alloy fusion reactor structural material with excellent mechanical properties.

2. The preparation steps of the present invention are simple and easy to operate. The preparation cycle of the high-entropy alloy is as low as 3 hours. The operation process only needs one step of vacuum arc melting to obtain solid solution strengthened (FeVCrMn) _x Ti _y low activation with uniform composition High-entropy alloy ingots.

3. The metal elements used in the preparation of materials in the present invention are all low-activation elements, that is, the induced radioactivity of the material after neutron irradiation in the future fusion reactor is low, which can not only further shorten the radiation resistance of the material after neutron irradiation The performance test cycle can also shorten the time for radioactive waste treatment and the recycling cycle of the material itself after the end of the future fusion reactor operation.

Description of drawings

Fig. 1 is the X-ray diffraction (XRD) spectrum of the low-activation high-entropy alloy of (FeVCrMn) ₉₅ Ti ₅ provided by the present invention;

Fig. 2 is that the composition provided by the present invention is (FeVCrMn) ₉₅ Ti ₅ The low-activation high-entropy alloy utilizes scanning electron microscope (SEM) to observe the microstructure;

Fig. 3 is the microstructure observed by a transmission electron microscope (TEM) of the low-activation high-entropy alloy (FeVCrMn) ₉₅ Ti ₅ provided by the present invention, wherein, (a) matrix high-resolution TEM image, (b ) TEM image of Ti-rich phase, (c) energy spectrum of Ti-rich phase;

Fig. 4 is the true stress-strain curve (room temperature) of the low-activation high-entropy alloy of (FeVCrMn) ₉₅ Ti ₅ provided by the present invention;

Fig. 5 is the XRD spectrum of the low-activation high-entropy alloy whose composition is (FeVCrMn) ₉₈ Ti ₂ provided by the present invention;

Fig. 6 is the microstructure observed by SEM of the low-activation high-entropy alloy whose composition is (FeVCrMn) ₉₈ Ti ₂ provided by the present invention;

Fig. 7 is the microstructure observed by TEM of the low-activation high-entropy alloy whose composition is (FeVCrMn) ₉₈ Ti ₂ provided by the present invention, wherein, (a) matrix high-resolution TEM image, (b) Ti-rich phase TEM Like, (c) energy spectrum of Ti-rich phase;

Fig. 8 is the true stress-strain curve (room temperature) of the low-activation high-entropy alloy with the composition (FeVCrMn) ₉₈ Ti ₂ provided by the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Ti为调节元素，原子百分数为y％。其中，Fe、V、Cr、Mn和Ti均是传统聚变堆结构材料如低活化铁素体/马氏体钢及钒合金的主要元素。采用固溶强化为主的强化方法，达到高强度的力学性能。A low-activation high-entropy alloy prepared by the present invention has a composition of (FeVCrMn) _x Ti _y , and in the chemical formula, x+y=100, x≥90, y≤10. Among them, Fe, V, Cr and Mn are the main components of equiatomic ratio, all of which are

Ti is an adjusting element, and the atomic percentage is y%. Among them, Fe, V, Cr, Mn and Ti are the main elements of traditional fusion reactor structural materials such as low activation ferrite/martensitic steel and vanadium alloy. The strengthening method based on solid solution strengthening is adopted to achieve high-strength mechanical properties.

This solid-solution strengthened low-activation high-entropy alloy has a single-phase body-centered cubic (BCC) structure, and the grain size is less than or equal to 200 μm. Hardness ≥ 400HV, elastic modulus about 200GPa, room temperature yield strength ≥ 700MPa, room temperature tensile strength ≥ 1200MPa. The strength of the low-activation high-entropy alloy is much higher than that of existing fusion reactor low-activation structural materials such as low-activation ferrite/martensitic steel and vanadium alloy.

The composition of this solid solution strengthened low activation high entropy alloy may be (FeVCrMn) ₉₈ Ti ₂ , which contains Fe, V, Cr, Mn with an atomic fraction of 24.5%, and Ti with an atomic fraction of 2%.

A further preferred component of this solid-solution strengthened low-activation high-entropy alloy can also be (FeVCrMn) ₉₅ Ti ₅ , which contains Fe, V, Cr, and Mn with an atomic fraction of 23.75%, and Ti with an atomic fraction of 5% . The increase of Ti content can significantly reduce the grain size of the alloy and improve the strength of the alloy.

The method for preparing this solid solution strengthened low-activation high-entropy alloy comprises the following steps:

1) Weigh the raw material particles of Fe, V, Cr, Mn and Ti elemental elements with a purity of ≥99.95% according to the atomic ratio, and put them into a water-cooled copper crucible of a vacuum arc melting furnace;

2) Carry out vacuum arc melting. Evacuate the vacuum chamber of the smelting furnace to ≤5×10 ^-3 Pa, and then fill it with high-purity argon gas with a purity of ≥99.999% until the pressure of the vacuum chamber is -0.8 to -0.6 MPa. High-purity argon is used as protective gas and arcing medium, and the melting current is 350-450A. Cooling water is passed during melting to prevent the water-cooled copper plate from overheating and melting. In order to make the alloy composition and structure homogeneous, the alloy ingot must be _smelted repeatedly for 3-5 times on the front and back sides, each time for 3-6 minutes, and the alloy stays in the liquid state for a total of _10-30 minutes. Activated high-entropy alloy ingots.

Example 1

A solid-solution strengthened low-activation high-entropy alloy, the composition of which is (FeVCrMn) ₉₅ Ti ₅ , which contains Fe, V, Cr, and Mn with an atomic fraction of 23.75% and Ti with an atomic fraction of 5%. Weigh the raw material particles of Fe, V, Cr, Mn and Ti elemental elements with a purity of ≥99.95% according to the atomic ratio, and put them into the water-cooled copper crucible of the vacuum arc melting furnace; vacuumize the vacuum chamber of the melting furnace to ≤ 4×10 ^-3 Pa, and then filled with high-purity argon with a purity ≥99.999% until the pressure of the vacuum chamber is -0.7MPa. High-purity argon is used as the shielding gas and arcing medium, the melting current is 400A, and cooling water is passed through during melting to prevent the water-cooled copper plate from overheating and melting. In order to make the alloy composition and structure uniform, the alloy ingot must be smelted repeatedly for 4 times on the front and back sides, each time for 5 minutes, and the alloy stays in the liquid state for a total of 20 minutes. After the final cooling, (FeVCrMn) ₉₅ Ti ₅ low activation high entropy alloy ingot was obtained.

合金的晶格常数异于各元素组元纯金属的晶格常数，表明合金元素的原子间引起了晶格畸变，起到了固溶强化作用。The density of (FeVCrMn) ₉₅ Ti ₅ low-activation high-entropy alloy measured by Archimedes drainage method is 7.008g/cm ³ . Utilize the HVS-1000A micro-Vickers hardness tester to test its hardness to be about 510HV. The DX-2700 X-ray diffractometer was used to analyze the phase of (FeVCrMn) ₉₅ Ti ₅ low-activation high-entropy alloy. The (110), (200), (211) crystal faces of the centered cubic (BCC) structure, (FeVCrMn) ₉₅ Ti ₅ low-activation high-entropy alloy has a single-phase BCC lattice structure. According to the Bragg equation λ=2dsinθ, the lattice constant is calculated as

The lattice constant of the alloy is different from the lattice constant of the pure metal of each element component, indicating that the lattice distortion is caused by the atoms of the alloy elements, which plays a role of solid solution strengthening.

Using a scanning electron microscope (SEM) to observe the microstructure of the low-activation high-entropy alloy (FeVCrMn) ₉₅ Ti ₅ prepared in this example, as shown in Figure 2, the (FeVCrMn) ₉₅ Ti ₅ low-activation high-entropy alloy The microstructure is equiaxed crystal with uniform distribution of elements. As shown in Figure 2, the Zeiss Auriga field emission scanning electron microscope was used to observe the grain size of 20-70 μm, with an average size of about 40 μm. The grains are relatively small and the alloy structure is relatively uniform. The microstructure of the low-activation high-entropy alloy (FeVCrMn) ₉₅ Ti ₅ prepared in this example was observed by a transmission electron microscope (TEM). The TEM morphology (including high-resolution images showing atomic arrangement) is shown in Figure 3, where (a) is the high-resolution TEM image of the matrix, (b) is the TEM image of the Ti-rich phase, and (c) is the energy spectrum of the Ti-rich phase. Various alloy elements are dissolved into the metal matrix, and different types of atoms are in solid solution with each other, resulting in serious lattice distortion, and the strength of high-entropy alloys is mainly improved by solid solution strengthening. The composition of the alloy matrix is 3.9Ti-24.1V-23.2Cr-22.5Mn-26.3Fe, which is close to the design composition. Among them, a Ti-rich phase with a size of about 1 μm is occasionally found, and its composition is 10.5Ti-15.4V-16.5Cr-24.8Mn-32.9Fe (wt.%), which contains a slightly higher content of Ti and Fe than the matrix. The segregated high-entropy alloy phase acts as a strengthening agent as the matrix.

The room temperature true stress-strain curve of the low-activation high-entropy alloy with the composition (FeVCrMn) ₉₅ Ti ₅ prepared in this example was obtained by testing the cylindrical plane indentation method, as shown in FIG. 4 . The elastic modulus of (FeVCrMn) ₉₅ Ti ₅ alloy is about 198GPa, the yield strength is about 1040MPa, the tensile strength is 1640MPa, the strain hardening exponent is 0.198, and the strain hardening coefficient is 2760. The strength of the high-entropy alloy is much higher than that of existing fusion reactor low-activation structural materials such as low-activation ferrite/martensitic steel and vanadium alloy (the tensile strength at room temperature is only 500-700MPa).

Example 2

A solid-solution strengthened low-activation high-entropy alloy, the composition of which is (FeVCrMn) ₉₈ Ti ₂ , which contains Fe, V, Cr, and Mn with an atomic fraction of 24.5% and Ti with an atomic fraction of 2%. Weigh the raw material particles of Fe, V, Cr, Mn and Ti elemental elements with a purity of ≥99.95% according to the atomic ratio, and put them into the water-cooled copper crucible of the vacuum arc melting furnace; vacuumize the vacuum chamber of the melting furnace to 3.5 × 10 ^-3 Pa, and then filled with high-purity argon with a purity ≥ 99.999% until the pressure of the vacuum chamber is -0.8MPa. High-purity argon is used as the shielding gas and arcing medium, the melting current is 390A, and cooling water is passed through during melting to prevent the water-cooled copper plate from overheating and melting. In order to make the alloy composition and structure homogeneous, the alloy ingot must be smelted repeatedly for 5 times on the front and back sides, each time for 3 minutes, and the alloy stays in the liquid state for a total of 15 minutes. After the final cooling, (FeVCrMn) ₉₅ Ti ₅ low activation high entropy alloy ingot was obtained.

合金的晶格常数异于各元素组元纯金属的晶格常数，表明合金元素的原子间引起了晶格畸变，起到了固溶强化作用。The density of (FeVCrMn) ₉₈ Ti ₂ low activation high entropy alloy measured by Archimedes drainage method is 7.053g/cm ³ . Utilize the HVS-1000A micro-Vickers hardness tester to test its hardness to be about 430HV. The phase analysis of (FeVCrMn) ₉₈ Ti ₂ low activation high entropy alloy was carried out by DX-2700 X-ray diffractometer. The results are shown in Figure 5. According to the lattice diffraction extinction law, it can be determined that the diffraction peaks in the spectrum correspond to the (110), (200), and (211) crystal planes of the BCC structure, and (FeVCrMn) ₉₈ Ti ₂ has low activation and high entropy The alloy has a single-phase body centered cubic (BCC) lattice structure. According to the Bragg equation, λ=2dsinθ, the calculated lattice constant is

The lattice constant of the alloy is different from the lattice constant of the pure metal of each element component, indicating that the lattice distortion is caused by the atoms of the alloy elements, which plays a role of solid solution strengthening.

As shown in Figure 6, the microstructure of (FeVCrMn) ₉₈ Ti ₂ low-activation high-entropy alloy observed by Zeiss Auriga field emission scanning electron microscope is an equiaxed crystal with uniform element distribution, the grain size is 20-200 μm, and the average size is about 120 μm , the grains are finer and the alloy structure is more uniform.

Figure 7 is the TEM microstructure of (FeVCrMn) ₉₈ Ti ₂ alloy, (a) is the high-resolution TEM image of the matrix, (b) is the TEM image of the Ti-rich phase, and (c) is the energy spectrum of the Ti-rich phase. Among them, the Ti-rich phase composition 96Ti-1.95V-0.8Cr-0.07Mn-0.62Fe (wt.%), compared with the matrix composition 0.71Ti-25.7V-27.9Cr-20.1Mn-25.6Fe (wt.%), the The Ti-rich phase may be a precipitated phase, but its Ti content is very high, which also plays a certain role in strengthening and toughening the alloy.

Its true stress-strain curve at room temperature is shown in Figure 8. According to the calculation of the relevant theoretical formulas of the plane indentation test, the elastic modulus of (FeVCrMn) ₉₈ Ti ₂ alloy is about 202GPa, the yield strength is about 760MPa, the tensile strength is about 1290MPa, and the strain Hardening index 0.204, strain hardening coefficient 2180. The strength of the high-entropy alloy is much higher than that of existing fusion reactor low-activation structural materials such as low-activation ferrite/martensitic steel and vanadium alloy.

The present invention has been described in detail above in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the above-mentioned embodiments, and can also be made without departing from the gist of the present invention within the scope of knowledge possessed by those of ordinary skill in the art. kind of change. The content that is not described in detail in the present invention can adopt the prior art.

Claims (6)

1. a kind of (FeVCrMn) _x Ti _y low activation high entropy alloy, it is characterized in that, in the chemical formula of (FeVCrMn) _x Ti _y low activation high entropy alloy, Fe, V, Cr and Mn are equiatomic ratio, x+y =100, 90≤x<100, 0<y≤10; (FeVCrMn) _x Ti _y low-activation high-entropy alloy has a single-phase body-centered cubic BCC structure, and the grain size is ≤200 μm. 2. a kind of (FeVCrMn) _x Ti _y low activation high entropy alloy according to claim 1, is characterized in that, described (FeVCrMn) _x Ti _y low activation high entropy alloy hardness ≥ 400HV, modulus of elasticity 200GPa, room temperature Yield strength ≥ 700MPa, room temperature tensile strength ≥ 1200MPa. 3. A kind of (FeVCrMn) _x Ti _y low-activation high-entropy alloy according to claim 1, characterized in that, in the chemical formula of (FeVCrMn) _x Ti _y low-activation high-entropy alloy, x=95, y= 5. 4. A kind of (FeVCrMn) _x Ti _y low-activation high-entropy alloy according to claim 1, characterized in that, in the chemical formula of (FeVCrMn) _x Ti _y low-activation high-entropy alloy, x=98, y= 2. 5. A method for preparing (FeVCrMn) _x Ti _y low-activation high-entropy alloy, for a kind of (FeVCrMn) _x Ti _y low-activation high-entropy alloy according to claim 1, characterized in that, the method comprises The following steps: Step 1, according to the atomic percentage of each element, weigh the raw materials of Fe, V, Cr, Mn and Ti elemental elements, and put them into the water-cooled copper crucible of the vacuum arc melting furnace; Step 2, vacuum arc melting the raw materials of Fe, V, Cr, Mn and Ti elemental elements put into the water-cooled copper crucible of the vacuum arc melting furnace. 6. A method for preparing (FeVCrMn) _x Ti _y low-activation high-entropy alloy according to claim 5, characterized in that, the step 2 is specifically: evacuating the vacuum chamber to ≤5×10 ^-3 Pa , and then filled with high-purity argon until the pressure of the vacuum chamber is -0.8 to -0.6MPa, the melting current is 350-450A, and the cooling water is passed during melting; the front and back sides of the alloy ingot are repeatedly smelted for 3-5 times, each time keeping 6 minutes, the alloy stays in the liquid state for a total of 10-30 minutes, and finally after cooling, a (FeVCrMn) _x Ti _y low-activation high-entropy alloy ingot is obtained.

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