A refractory multi-component alloy and its preparation method

Abstract

The present invention discloses a refractory multi-component alloy and a preparation method thereof. The refractory multi-component alloy is composed of refractory elements, denoted as AaBbCcDd, where A, B, C, and D are any four elements among W, Ta, Mo, Nb, Hf, Zr, and V. The atomic percentage contents of the elements satisfy 5% ≤ a ≤ 70%, 5% ≤ b ≤ 70%, 5% ≤ c ≤ 70%, 5% ≤ d ≤ 70%, and a + b + c + d = 100. The method is as follows: weighing the elemental metal raw materials according to the atomic ratio; placing them in a non-consumable vacuum arc melting furnace; performing arc melting; and cooling to room temperature to obtain the alloy. In the alloy matrix phase of the present invention, fine and dispersed second phases are spontaneously generated, enabling the alloy to have high strength and good plasticity at room temperature. While achieving a strength of 3100 MPa, it still has a deformation amount of more than 26%. It also has high high-temperature strength and still maintains a strength of more than 1600 MPa at 800°C.

Description

Technical Field

[0001] The present invention relates to a multi-component metallic material and a preparation method thereof, and particularly to a refractory multi-component alloy and a preparation method thereof. Background Art

[0002] Multi-component alloys are different from traditional alloys which mainly contain one or two alloying elements, greatly expanding the alloy composition range and enriching the types of alloy materials. Multi-component alloys contain multiple elements with chaotic atomic arrangements. However, instead of generating a large number of intermetallic compounds or amorphous substances due to strong interatomic interactions, they usually present a simple solid solution structure. However, due to the relatively complex element types in the solid solution and large lattice distortion, the solid solution is in a metastable state, and other phases can be precipitated from the matrix phase after certain subsequent treatments. Based on their special structures, multi-component alloys usually exhibit excellent properties, such as high hardness, high modulus, outstanding high-temperature strength, good corrosion resistance and radiation resistance, etc.

[0003] Refractory multi-component alloys are based on refractory elements such as W, Re, Ta, Mo, Nb, Hf, Zr, Ti, V, Cr, etc. as the main elements, mainly for high-temperature applications. While having the excellent properties of multi-component alloys, they have good tissue stability and mechanical properties at high temperatures, which can make up for the drawbacks that the mechanical properties of traditional high-temperature alloys reach the application limit at high temperatures and cannot be applied at higher temperatures. They have good application prospects in industries such as aerospace, electric power energy, chemical engineering, etc.

[0004] In 2010, Senkov et al. first reported two refractory multi-component alloys, MoNbTaW and MoNbTaVW. These two alloys are still the alloys with the highest strength at 1600 °C ultra-high temperature and are expected to be applied in extreme high-temperature environments. However, their low room-temperature strength, large brittleness, poor oxidation resistance, and difficult forming limit their wider application. Subsequently reported HfNbTaTiZr alloy has excellent room-temperature plasticity and toughness, with a compressive strain exceeding 50% and good processing performance. However, its high-temperature softening is serious, and its high-temperature strength is much lower than that of the MoNbTaW alloy, unable to meet the use requirements of high-temperature structural components. Although subsequent researchers have done a lot of work, such as adding light alloy elements, introducing non-metallic elements, changing preparation methods, etc., to try to change this situation, the room-temperature plasticity and high-temperature strength of refractory multi-component alloys still cannot be balanced. For example, Patent CN 110541103 A improved the HfTiNbV multi-component alloy through an alloying method, and its room-temperature plasticity was greatly improved, but its room-temperature yield strength was lower than 1000 MPa; Patent CN 109898005 A prepared WTaVZrHf with a high strength of 1600 MPa at room temperature by means of spark plasma sintering, but it basically has no plastic stage.

[0005] In summary, the existing refractory multi-component alloy systems still have significant limitations in practical applications. The main problem is that it is impossible to have both room-temperature plasticity and high-temperature strength at the same time. Summary of the Invention

[0006] Object of the Invention: The object of the present invention is to provide a refractory multi-component alloy that can have both high strength at room temperature and good room-temperature plasticity;

[0007] The second object of the present invention is to provide a method for preparing the above-mentioned refractory multi-component alloy.

[0008] Technical Solution: The refractory multi-component alloy of the present invention is composed of refractory elements, denoted as AaBbCcDd, where A, B, C, and D are any four elements among W, Ta, Mo, Nb, Hf, Zr, and V, and the atomic percentage contents of the elements satisfy 5% ≤ a ≤ 70%, 5% ≤ b ≤ 70%, 5% ≤ c ≤ 70%, 5% ≤ d ≤ 70%, and a + b + c + d = 100%.

[0009] Among them, when the BCC phase-stabilizing element in the refractory multi-component alloy is lower than the threshold value, the refractory multi-component alloy is a duplex structure; the range of the threshold value is 10-25%; by reducing the content of the HCP phase-stabilizing element in the refractory multi-component alloy, during the process of approaching the threshold value, the structure of the refractory multi-component alloy transitions from a single-phase structure to a multi-phase structure, and the performance gradually improves; when it is lower than the threshold value and a second phase is formed, the performance improvement is more obvious.

[0010] Among them, when the HCP phase-stabilizing element in the refractory multi-component alloy is higher than the threshold value, the refractory multi-component alloy is a duplex structure; the range of the threshold value is 10-25%; by increasing the content of the HCP phase-stabilizing element in the refractory multi-component alloy, during the process of approaching the threshold value, the structure of the refractory multi-component alloy transitions from a single-phase structure to a multi-phase structure, and the performance gradually improves; when it exceeds the threshold value and a second phase is formed, the performance improvement is more obvious.

[0011] Among them, for the refractory multi-component alloy A a B b C c D d A is Hf, B is Nb, C is Ta, D is W, and a is greater than or equal to 25%; the refractory multi-component alloy is a duplex structure.

[0012] Among them, for the refractory multi-component alloy A a B b C c D d A is Hf, B is Nb, C is Ta, D is W, and b, c, or d is less than or equal to 25%; the refractory multi-component alloy is a duplex structure.

[0013] The preparation method of the refractory multi-component alloy described above includes the following steps:

[0014] (1) Grind the elemental metal raw materials to remove the surface oxide film, and weigh them according to the atomic ratio after cleaning;

[0015] (2) Place the weighed raw materials in a water-cooled copper mold crucible of a non-consumable vacuum arc melting furnace, and evacuate the air pressure in the vacuum chamber of the vacuum arc melting furnace to below 4×10 -3 Pa, and fill in the protective gas;

[0016] (3) Carry out arc melting;

[0017] (4) Take out the alloy ingot when it cools down to room temperature in the vacuum chamber to obtain the refractory multi-component alloy.

[0018] Among them, in step (3), before arc melting, first melt the titanium ingot to remove the residual oxygen in the furnace cavity; the melting voltage when melting the titanium ingot is 20 - 40 V, and the melting current is 100 - 200 A; the melting voltage when melting the alloy ingot is 20 - 40 V, and the melting current is 250 - 400 A.

[0019] When the percentage content of the BCC phase stabilizing element in the refractory multi-component alloy is less than 25%, or less than 10%, the refractory multi-component alloy is a duplex structure.

[0020] Among them, when the percentage content of the HCP phase stabilizing element in the refractory multi-component alloy is higher than 10%, or higher than 25%, the refractory multi-component alloy is a duplex structure.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following remarkable effects: 1. Within the elemental atomic percentages of the present invention, when specific phase stabilizing elements are higher or lower than the threshold values, fine and dispersed second phases spontaneously form in the alloy matrix phase, enabling the alloy to have high strength and good plasticity at room temperature, with a strength of up to 3100 MPa while still having a deformation amount of more than 26%, and also having high high-temperature strength, remaining above 1600 MPa at 800 °C; 2. By reasonably adjusting the alloy element content, adjusting the morphology, content, distribution and size of the second phase, etc., and using a non-consumable vacuum arc melting furnace, a series of refractory multi-component alloys have been prepared. The alloy is in a single BCC phase or duplex structure, the microstructure morphology is mainly dendritic, the average grain size is significantly smaller than that of ordinary superalloys, and the room temperature and high-temperature mechanical properties are significantly improved; 3. The present invention significantly improves the room temperature and high-temperature mechanical properties of the refractory multi-component alloy, increases its room temperature and high-temperature forgeability, and has broad application prospects in the fields of aerospace, chemical engineering, mechanical manufacturing, transportation, electric power energy, etc. Description of the Drawings

[0022] Figure 1 For Ta described in Example 1 30 W 30 Nb 30 Hf 10 X-ray diffraction pattern of the refractory multi-component alloy;

[0023] Figure 2 For Ta described in Example 1 30 W 30 Nb 30 Hf 10 Room temperature stress-strain curve of the refractory multi-component alloy;

[0024] Figure 3 For Ta described in Example 1 30 W 30 Nb 30 Hf 10 Stress-strain curve of the refractory multi-component alloy at 800 °C;

[0025] Figure 4 For Ta described in Example 2 25 W 25 Nb 25 Hf 25 X-ray diffraction pattern of the refractory multi-component alloy;

[0026] Figure 5 For Ta described in Example 2 25 W 25 Nb 25 Hf 25 Room temperature stress-strain curve of the refractory multi-component alloy;

[0027] Figure 6 For Ta described in Example 2 25 W 25 Nb 25 Hf 25 Stress-strain curve of the refractory multi-component alloy at 800 °C;

[0028] Figure 7 For Ta described in Example 3 18.33 W 18.33 Nb 18.33 Hf 45 X-ray diffraction pattern of the refractory multi-component alloy;

[0029] Figure 8 For Ta described in Example 3 18.33 W 18.33 Nb 18.33 Hf 45 Room temperature stress-strain curve of the refractory multi-component alloy;

[0030] Figure 9 Ta as described in Example 3 18.33 W 18.33 Nb 18.33 Hf 45 Stress-strain curves of refractory multi-component alloy at 800 ℃. DETAILED DESCRIPTION

[0031] The present invention is described in further detail below.

[0032] Example 1

[0033] Take pure metal particles of Hf, Nb, Ta, and W with a purity of not less than 99.95 wt.%, mechanically polish to remove the oxide scale, ultrasonically clean and blow dry, and then mix them according to the atomic ratio of 30 at.% Ta-30 at.% W-30 at.% Nb-10 at.% Hf. The weighed pure metal raw materials are placed in the water-cooled copper mold crucible of the non-consumable vacuum arc melting furnace in the order of the melting point of the elements from low to high. Before melting, the furnace chamber is evacuated to 4×10 -3 Pa, and then filled with argon to 0.07 MPa. During smelting, the titanium ingot in the furnace was first smelted for 3 min to remove the residual oxygen in the furnace chamber; when smelting the target alloy, the alloy was kept for 180 s after it was completely melted, then cooled, turned over and smelted again, and smelted 6 times in total to ensure uniform alloy composition.

[0034] A small sample of 10 mm × 10 mm × 4 mm was cut from the alloy ingot by wire cutting. The sample surface was smoothed with sandpaper, ultrasonically cleaned and blown dry, and then subjected to X-ray diffraction test. The detailed test parameters were scanning step length of 0.02° / s, scanning rate of 0.15 s / step, and scanning angle 2θ range of 20°~100°. The X-ray diffraction spectrum of the refractory multi-component alloy prepared in Example 1 is shown in the attached figure. Figure 1 It can be seen that the refractory multi-component alloy prepared in Example 1 has a single BCC structure.

[0035] A cylindrical specimen of φ2×4 mm was cut from the middle of the alloy ingot by wire cutting. The wire cutting marks on the bottom of the cylindrical specimen and the oxide scale on the side were gently ground off with 2000-grit sandpaper. After ultrasonic cleaning and drying, the room temperature mechanical properties of the alloy were tested using a Sans5305 universal testing machine. Figure 2 The room temperature stress-strain curve of the refractory multi-component alloy prepared in Example 1. It can be seen that the yield strength of the refractory multi-component alloy is 1676 MPa, the compressive strength is 2380 MPa, and the fracture strain is more than 14%.

[0036] A cylindrical sample with a diameter of φ2×4 mm was cut from the middle of the alloy ingot by wire cutting. The wire cutting marks on the bottom surface of the cylindrical sample and the oxide scale on the side surface were gently ground off with 2000-mesh sandpaper. After ultrasonic cleaning and drying, the high-temperature mechanical properties of the alloy were tested using a Sans5305 universal testing machine and an external high-temperature furnace. Attached Figure 3 Figure 136 shows the stress-strain curve of the refractory multi-component alloy prepared in Example 1 in an 800 °C air environment. It can be seen that the yield strength of the refractory multi-component alloy is 1174 MPa, the compressive strength is 1761 MPa, and the fracture strain is 20%. This indicates that the refractory multi-component alloy has excellent comprehensive mechanical properties in a wide temperature range.

[0037] Example 2

[0038] Pure metal particles of Hf, Nb, Ta, and W with a purity of not less than 99.95 wt.% were taken. After mechanical grinding to remove the oxide scale and ultrasonic cleaning and drying, precise batching was carried out according to an atomic ratio of 25 at.% Ta - 25 at.% W - 25 at.% Nb - 25 at.% Hf. The weighed pure metal raw materials were successively placed in a water-cooled copper mold crucible of a non-consumable vacuum arc melting furnace in the order of increasing element melting point. Before melting, the furnace chamber was evacuated to 4×10 -3 Pa, and then filled with argon to 0.07 MPa. During melting, the titanium ingot in the furnace was first melted for 3 min to remove the residual oxygen in the furnace chamber; when melting the target alloy, after the alloy was completely melted, it was held for 180 s, then cooled, the alloy ingot was flipped, and melted again. A total of 6 melts were carried out to ensure uniform alloy composition.

[0039] A small sample with a size of 10 mm×10 mm×4 mm was cut from the alloy ingot by wire cutting. After the surface of the sample was ground flat with sandpaper and ultrasonic cleaned and dried, X-ray diffraction testing was carried out on it. The detailed testing parameters were a scanning step size of 0.02°, a scanning rate of 0.15 s / step, and a scanning angle 2θ range of 20° to 100°. The X-ray diffraction pattern of the refractory multi-component alloy prepared in Example 2 is as attached Figure 4 shown. It can be seen that the refractory multi-component alloy prepared in Example 2 has a BCC and HCP duplex structure.

[0040] A cylindrical sample with a diameter of φ2×4 mm was cut from the middle of the alloy ingot by wire cutting. The wire cutting marks on the bottom surface of the cylindrical sample and the oxide scale on the side surface were gently ground off with 2000-mesh sandpaper. After ultrasonic cleaning and drying, the room-temperature mechanical properties of the alloy were tested using a Sans5305 universal testing machine. Attached Figure 5 Figure 146 shows the room-temperature stress-strain curve of the refractory multi-component alloy prepared in Example 2. It can be seen that the yield strength of the refractory multi-component alloy is 2088 MPa, the compressive strength is 2705 MPa, and the fracture strain is more than 16%.

[0041] A cylindrical sample with a diameter of φ2×4 mm was cut from the middle of the alloy ingot by wire cutting. The wire cutting marks on the bottom surface of the cylindrical sample and the oxide scale on the side surface were gently ground off with 2000-mesh sandpaper. After ultrasonic cleaning and drying, the high-temperature mechanical properties of the alloy were tested using a Sans5305 universal testing machine and an external high-temperature furnace. Attached Figure 6 is the stress-strain curve of the refractory multi-component alloy prepared in Example 2 in an 800 °C atmospheric environment. It can be seen that the yield strength of the refractory multi-component alloy is 1254 MPa, the compressive strength is 1851 MPa, and the fracture strain is 20%, indicating that the refractory multi-component alloy has excellent comprehensive mechanical properties in a wide temperature range.

[0042] Example 3

[0043] Pure metal particles of Hf, Nb, Ta, and W with a purity of not less than 99.95 wt.% were taken. After mechanical grinding to remove the oxide scale and ultrasonic cleaning and drying, precise batching was carried out according to the atomic ratio of 18.33 at.% Ta - 18.33 at.% W - 18.33 at.% Nb - 45 at.% Hf. The weighed pure metal raw materials were successively placed in a water-cooled copper mold crucible of a non-consumable vacuum arc melting furnace in the order of increasing element melting point. Before melting, the furnace chamber was evacuated to 4×10 -3 Pa, and then filled with argon to 0.07 MPa. During melting, the titanium ingot in the furnace was first melted for 3 min to remove the residual oxygen in the furnace chamber; when melting the target alloy, after the alloy was completely melted, it was held for 180 s, and then the alloy ingot was cooled, flipped, and melted again. A total of 6 melts were carried out to ensure uniform alloy composition.

[0044] A small sample with dimensions of 10 mm×10 mm×4 mm was cut from the alloy ingot by wire cutting. After the surface of the sample was ground flat with sandpaper and ultrasonic cleaned and dried, X-ray diffraction testing was performed on it. The detailed testing parameters were a scanning step size of 0.02°, a scanning rate of 0.15 s / step, and a scanning angle 2θ range of 20° to 100°. The X-ray diffraction pattern of the refractory multi-component alloy prepared in Example 2 is as attached Figure 7 shown. It can be seen that the refractory multi-component alloy prepared in Example 3 has a BCC and HCP duplex structure.

[0045] A cylindrical sample with a diameter of φ2×4 mm was cut from the middle of the alloy ingot by wire cutting. The wire cutting marks on the bottom surface of the cylindrical sample and the oxide scale on the side surface were gently ground off with 2000-mesh sandpaper. After ultrasonic cleaning and drying, the room-temperature mechanical properties of the alloy were tested using a Sans5305 universal testing machine. Attached Figure 8The room-temperature stress-strain curve of the refractory multi-component alloy prepared in Example 3. It can be seen that the yield strength of the refractory multi-component alloy is 2068 MPa, the compressive strength is 3135 MPa, and the fracture strain exceeds 26%. Compared with the reported refractory high-entropy alloys, the strength and plasticity of the refractory multi-component alloy prepared in this example are improved simultaneously.

[0046] Use wire cutting to cut a φ2×4 mm cylindrical specimen from the middle of the alloy ingot. Gently grind off the wire cutting marks on the bottom surface and the oxide scale on the side surface of the cylindrical specimen with 2000-mesh sandpaper. After ultrasonic cleaning and drying, use a Sans5305 universal testing machine and an external high-temperature furnace to test the high-temperature mechanical properties of the alloy. Attached Figure 9 The stress-strain curve of the refractory multi-component alloy prepared in Example 3 in an 800 °C atmospheric environment. It can be seen that the yield strength of the refractory multi-component alloy is 1477 MPa, the compressive strength is 1899 MPa, and the fracture strain is 20%, indicating that the refractory multi-component alloy has excellent comprehensive mechanical properties in a wide temperature range.

Claims

1. A refractory multi-component alloy, characterized in that, the refractory multi-component alloy is composed of refractory elements, denoted as AaBbCcDd, and the atomic percentage content of the elements satisfies 5% ≤ a ≤ 70%, 5% ≤ b ≤ 70%, 5% ≤ c ≤ 70%, 5% ≤ d ≤ 70%, and a + b + c + d = 100%; The refractory multi-component alloy A a B b C c D d wherein A is Hf, B is Nb, C is Ta, D is W, a is greater than or equal to 25%; b, c or d is less than or equal to 25%; the refractory multi-component alloy is a BCC and HCP duplex structure; the refractory multi-component alloy has a deformation amount of more than 26% while reaching a strength of 3100 MPa at room temperature.

2. A preparation method of the refractory multi-component alloy according to claim 1, characterized in that, it includes the following steps: (1) Grinding the elemental metal raw materials to remove the surface oxide film, weighing them according to the atomic ratio after cleaning; (2) Place the weighed raw materials in the water-cooled copper mold crucible of the non-consumable vacuum arc melting furnace, and evacuate the air pressure in the vacuum chamber of the vacuum arc melting furnace to below 4×10 -3 Pa, and then fill it with a protective gas; (3) Performing arc melting; (4) Taking out the alloy ingot when the vacuum chamber cools down to room temperature to obtain the refractory multi-component alloy.

3. According to the preparation method of the refractory multi-component alloy described in claim 2, characterized in that, in step (3), before arc melting, first melt the titanium ingot to remove the residual oxygen in the furnace cavity; the melting voltage when melting the titanium ingot is 20 - 40 V, and the melting current is 100 - 200 A; the melting voltage when melting the alloy ingot is 20 - 40 V, and the melting current is 250 - 400 A.

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