CN116445787B - A nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness and its preparation method - Google Patents

Abstract

A nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness and a preparation method thereof, which relates to a Nb-Si high-temperature remelted alloy and a preparation method thereof. The invention aims to solve the problem of low room temperature toughness and high temperature strength caused by coarse structure of niobium silicon alloy ingot. Nanoeutectic Nb‑Si high temperature remelted alloy: According to atomic percentage, its general chemical formula is Nb‑16Si‑20Ti‑1ZrC‑xSc, where x is 0.02～0.5; Preparation: 1. Weigh the raw materials; 2. Cast Preparation of ingots; 3. Preparation of metal plates; 4. Electron beam remelting; The present invention is used for nanoeutectic Nb-Si high temperature remelting alloys with both high strength and room temperature toughness and their preparation.

Description

A nanoeutectic Nb-Si high temperature remelted alloy with both high strength and room temperature toughness and preparation method thereof

Technical field

The invention relates to a Nb-Si high temperature remelting alloy and a preparation method thereof.

Background technique

With the advancement and development of science and technology and society, the demand for high-performance aero engines is increasing day by day. The temperature-bearing capacity of engine blades and other hot-end components determines the thrust-to-weight ratio of the engine. The currently widely used blade material, Ni-based single crystal, is limited by its melting point and cannot meet the high thrust-to-weight ratio requirements of next-generation engines. Based on this, a material with a higher melting point and better high-temperature performance is developed to meet the requirements of engine blade materials. Temperature-bearing capacity has profound implications.

Nb-Si alloy is usually composed of room temperature toughened Nbss phase and high temperature reinforced silicide phase, with a melting point as high as 1900°C and a density of only 7g/cm ³ ~ 7.2g/cm ³ . It is a potential high-temperature material to replace Ni-based single crystals. . However, the existing Nb-Si-based alloy preparation technology includes arc melting, directional solidification, etc. The obtained microstructure is coarse, especially the large-sized silicide phase, which significantly deteriorates the room temperature toughness and high-temperature strength, becoming an obstacle to Nb-Si-based alloys. An important "barrier" to application. Therefore, finding suitable processing and preparation techniques to prepare nanoscale eutectic Nb-Si superalloys is a top priority.

Contents of the invention

The present invention solves the problem of coarse niobium-silicon alloy ingot structure, resulting in low room temperature toughness and high temperature strength, and further provides a nanoeutectic Nb-Si high temperature remelted alloy with both high strength and room temperature toughness and a preparation method thereof.

A nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness. In terms of atomic percentage, its general chemical formula is Nb-16Si-20Ti-1ZrC-xSc, where x is 0.02 to 0.5.

A method for preparing a nano-eutectic Nb-Si high-temperature remelting alloy having both high strength and room temperature toughness is carried out in the following steps:

1. Weigh elemental Si, elemental Ti, ZrC, elemental Sc and elemental Nb according to the proportion of atomic percentages of 16% Si, 20% Ti, 1% ZrC, x% Sc and 63-x% Nb to obtain the weighed raw materials ;The x is 0.02～0.5;

2. Place the weighed raw materials in the smelting chamber from bottom to top in order according to the particle size from small to large, and smelt them in an argon atmosphere to obtain an ingot;

3. Cut the ingot into plates, polish to remove traces of wire cutting, and finally clean to obtain a metal plate;

Fourth, fix the metal plate on the platform of the electron beam deposition chamber, evacuate the chamber, and then introduce protective argon gas. Preheat the metal plate with a beam current of 10mA to 15mA. Then, remelt the preheated metal plate with a beam current of 24mA to 26mA at a moving speed of 100mm/min to 400mm/min. Finally, cool it with the furnace to obtain a nano-eutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness.

The beneficial effects of the present invention are:

1. The present invention uses two materials, ZrC and Sc, because ZrC can promote the decomposition of the large-sized Nb ₃ Si phase in Nb-Si-based alloys into the eutectic Nbss/Nb ₅ Si ₃ structure, and the addition of Sc is enriched during the preparation process. The formation of component supercooling at the front edge of the solid-liquid interface further refines the eutectic Nbss/Nb ₅ Si ₃ structure, thus improving the room temperature toughness and strength of Nb-Si-based alloys;

2. Use electron beam remelting to prepare Nb-Si-based alloys. Due to deep supercooling, Nb-Si high-temperature alloys with nano-eutectic Nbss/Nb ₅ Si ₃ structure can be obtained. The fine-sized eutectic structure has more phases due to The interface can evenly distribute the stress concentration generated during the fracture process, thereby further improving the room temperature toughness and strength of Nb-Si-based alloys;

3. The present invention uses the beam intensity and scanning rate in the electron beam remelting technology to control the temperature gradient and supercooling degree during the solidification of the Nb-Si-based high-temperature alloy, thereby controlling the crystal morphology and growth direction of the solidified structure, and obtaining two properties. The dendritic morphology structure of phase composite growth. The Nb-16Si-20Ti-1ZrC-xSc alloy (x is 0.02~0.5) designed by the present invention has high strength and room temperature toughness: the room temperature fracture toughness is as high as 22MPa·m ^1/2 ~ 40MPa·m ^1/2 , and the room temperature compressive strength reaches 2200MPa ~ 2800MPa, high temperature compressive strength is 391MPa ~ 456MPa, the alloy has excellent room temperature toughness and strength properties, and is a Nb-Si based high temperature alloy with great potential.

The invention is used for a nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness and its preparation method.

Description of drawings

Figure 1 is a microstructure diagram of the Nb-16Si-20Ti-1ZrC-0.02Sc remelted alloy prepared in Example 1;

Figure 2 is a microstructure diagram of the Nb-16Si-20Ti-1ZrC-0.05Sc remelted alloy prepared in Example 2;

FIG3 is a microstructure diagram of the Nb-16Si-20Ti-1ZrC-0.5Sc remelted alloy prepared in Example 3;

FIG4 is a room temperature fracture toughness diagram of the remelted Nb-Si alloys prepared in Examples 1 to 3;

Figure 5 is a room temperature compressive strength diagram of the remelted Nb-Si alloy prepared in Examples 1 to 3;

Figure 6 is a high temperature (1200°C) compressive strength diagram of the remelted Nb-Si alloy prepared in Examples 1 to 3.

Detailed ways

Specific Embodiment 1: This embodiment is a nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness. In terms of atomic percentage, its general chemical formula is Nb-16Si-20Ti-1ZrC-xSc, where , x is 0.02~0.5.

The beneficial effects of this implementation are:

1. This embodiment uses two materials, ZrC and Sc, because ZrC can promote the decomposition of the large-sized Nb ₃ Si phase in the Nb-Si-based alloy into the eutectic Nbss/Nb ₅ Si ₃ structure. The addition of Sc enriches the The component supercooling formed at the front edge of the solid-liquid interface further refines the eutectic Nbss/Nb ₅ Si ₃ structure, thereby improving the room temperature toughness and strength of the Nb-Si-based alloy;

2. Use electron beam remelting to prepare Nb-Si-based alloys. Due to deep supercooling, Nb-Si high-temperature alloys with nano-eutectic Nbss/Nb ₅ Si ₃ structure can be obtained. The fine-sized eutectic structure has more phases due to The interface can evenly distribute the stress concentration generated during the fracture process, thereby further improving the room temperature toughness and strength of Nb-Si-based alloys;

3. This embodiment uses the beam intensity and scanning rate in the electron beam remelting technology to control the temperature gradient and supercooling degree during the solidification of the Nb-Si-based high-temperature alloy, thereby controlling the crystal morphology and growth direction of the solidified structure, and obtaining The dendrite morphology of composite growth of two phases. The Nb-16Si-20Ti-1ZrC-xSc alloy (x is 0.02~0.5) designed in this embodiment has high strength and room temperature toughness: room temperature fracture toughness is as high as 22MPa·m ^1/2 ~ 40MPa·m ^1/2 and room temperature compressive strength Reaching 2200MPa ~ 2800MPa, the high temperature compressive strength is 391MPa ~ 456MPa. The alloy has excellent room temperature toughness and strength properties. It is a Nb-Si based high temperature alloy with great potential.

Specific implementation method 2: This implementation method is a method for preparing a nano-eutectic Nb-Si high-temperature remelting alloy with both high strength and room temperature toughness, which is carried out in the following steps:

1. Weighing elemental Si, elemental Ti, elemental ZrC, elemental Sc and elemental Nb in a ratio of 16% Si, 20% Ti, 1% ZrC, x% Sc and 63-x% Nb by atomic percentage to obtain weighed raw materials; wherein x is 0.02 to 0.5;

2. According to the particle size from small to large, the weighed raw materials are placed in the smelting chamber from bottom to top, and smelted in an argon atmosphere to obtain an ingot;

3. Cut the ingot into plates, polish to remove traces of wire cutting, and finally clean to obtain a metal plate;

4. Fix the metal plate on the platform of the electron beam deposition chamber, evacuate, and then pass in protective argon gas. Use a beam current of 10mA to 15mA to preheat the metal plate, and then use a beam current of 24mA to 26mA. The preheated metal plate is remelted at a moving speed of 100mm/min to 400mm/min, and finally cooled in the furnace to obtain a nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness. .

Specific embodiment three: The difference between this embodiment and the second embodiment is that the argon atmosphere described in step two is introduced according to the following steps: first, the smelting chamber is evacuated to 10Pa ~ 20Pa, and then the argon atmosphere is introduced into the protective chamber. Apply protective argon gas for 10s to 20s, repeat vacuuming and flowing argon gas three times, then vacuum to 3×10 ^-3 Pa ~ 4×10 ^-3 Pa, and finally pump in protective argon gas to 400Pa ~ 500a. Others are the same as the second embodiment.

Specific Embodiment 4: The difference between this embodiment and either Specific Embodiment 2 or 3 is that in step 2, the melting is carried out under the conditions of argon atmosphere and current of 600A. Others are the same as the second or third embodiment.

Specific embodiment 5: This embodiment is different from specific embodiments 2 to 4 in that the melting is repeated 6 to 7 times in the argon atmosphere in step 2. The rest is the same as specific embodiments 2 to 4.

Specific embodiment 6: This embodiment is different from specific embodiments 2 to 5 in that: in step 2, the weighed raw materials are placed in the smelting chamber from bottom to top in order according to the particle size from small to large, and the single substance Ti is first smelted under an argon atmosphere, and then the other weighed raw materials are smelted to obtain an ingot. The rest is the same as specific embodiments 2 to 5.

In this embodiment, in order to further reduce the oxygen content in the smelting chamber, titanium sponge particles are first smelted.

Specific Embodiment 7: The difference between this embodiment and one of Specific Embodiments 2 to 6 is that in step three, 800# water-sanding paper is used to polish to remove traces of line cutting, and finally alcohol is used for cleaning. Others are the same as specific embodiments two to six.

Specific Embodiment 8: The difference between this embodiment and one of Specific Embodiments 2 to 7 is that in step 4, the vacuum is evacuated to 3×10 ^-3 Pa ~ 4×10 ^-3 Pa, and then protective argon gas is introduced to 200 Pa. ~500Pa. Others are the same as the second to seventh embodiments.

Specific Embodiment 9: The difference between this implementation and one of Specific Embodiments 2 to 8 is that in step 4, a beam with a current of 25 mA is used to preheat the beam at a moving speed of 100 mm/min ~ 400 mm/min. The final metal plate is remelted. Others are the same as the second to eighth embodiments.

Specific Embodiment 10: The difference between this embodiment and one of Specific Embodiments 2 to 9 is that in step 4, a beam with a current of 25 mA is used to treat the preheated metal plate at a moving speed of 400 mm/min. Perform remelting. Others are the same as the second to ninth embodiments.

The following examples are used to verify the beneficial effects of the present invention:

Example 1:

A nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness. In terms of atomic percentage, its general chemical formula is Nb-16Si-20Ti-1ZrC-0.02Sc.

The preparation method of the nano eutectic Nb-Si high temperature remelting alloy having both high strength and room temperature toughness is carried out according to the following steps:

1. Weighing elemental Si, elemental Ti, elemental ZrC, elemental Sc and elemental Nb in a ratio of 16% Si, 20% Ti, 1% ZrC, 0.02% Sc and 62.98% Nb by atomic percentage to obtain weighed raw materials;

2. According to the particle size from small to large, place the weighed raw materials in the non-consumable water-cooled copper crucible from bottom to top, and then place it in the smelting chamber. Use a mechanical pump to evacuate the smelting chamber to 15Pa, and then pass it into Apply protective argon gas for 20 seconds, repeat vacuuming and flowing argon gas three times, then use a molecular pump to evacuate the smelting chamber to 3×10 ^-3 Pa, and finally introduce protective argon gas to 500 Pa, and then in the argon atmosphere and current Under the condition of 600A, first smelt elemental Ti, then smelt other weighed raw materials, and repeat smelting 6 times to obtain an ingot;

3. Use electric spark to cut the ingot into plates, use 800# water-sanding paper to polish to remove traces of wire cutting, and finally use alcohol to clean to obtain a metal plate;

4. Fix the metal plate on the platform of the electron beam deposition chamber, evacuate it to 3×10 ^-3 Pa, then introduce protective argon gas to 200Pa, use a beam current of 15mA to preheat the metal plate, and then use a current of 15mA to preheat the metal plate. The preheated metal plate is remelted with a 25mA beam current at a moving speed of 100mm/min, and finally cooled in the furnace to obtain nanoeutectic Nb-Si high-temperature remelting with both high strength and room temperature toughness. Alloy, namely Nb-16Si-20Ti-1ZrC-0.02Sc remelted alloy.

The elemental Si described in step 1 is a small-sized block crystal with a size of 3nm to 5mm, the elemental Ti is a sponge block with a size of 2mm to 4mm, the ZrC is a powder with a particle size of 400 mesh, and the elemental Ti is a powder with a particle size of 400 mesh. Sc is a filament with a diameter of 1mm, and the elemental Nb is a small-sized plate with a size of 10mm×10mm×1mm;

The order from bottom to top described in step 2 is ZrC, elemental Sc, elemental Ti, elemental Si and elemental Nb;

Figure 1 is a microstructure diagram of the Nb-16Si-20Ti-1ZrC-0.02Sc remelted alloy prepared in Example 1; it can be seen from the figure that the structure of the Nb-16Si-20Ti-1ZrC-0.02Sc remelted alloy in Example 1 is fine, and is a dendrite morphology structure of two-phase composite growth. The size of the Nbss/Nb ₅ Si ₃ eutectic structure phase varies from 500nm to 900nm, and there is no large-sized primary silicide phase.

Embodiment 2: The difference between this embodiment and Embodiment 1 is that it is a nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness. In terms of atomic percentage, its general chemical formula is Nb-16Si- 20Ti-1ZrC-0.05Sc; in step 1, weigh elemental Si, elemental Ti, ZrC, elemental Sc and elemental Nb according to the ratio of atomic percentages of 16% Si, 20% Ti, 1% ZrC, 0.05% Sc and 62.95% Nb. ; Step 4: Use a beam current of 25mA to remelt the preheated metal plate at a moving speed of 200mm/min. Others are the same as Embodiment 1.

Figure 2 is a microstructure diagram of the Nb-16Si-20Ti-1ZrC-0.05Sc remelted alloy prepared in Example 2; it can be seen from the figure that the structure of the Nb-16Si-20Ti-1ZrC-0.05Sc remelted alloy in Example 2 It is small and has a dendritic morphology of two-phase compound growth. The Nbss/Nb ₅ Si ₃ eutectic phase size ranges from 700nm to 900nm, and there is no large-sized primary silicide phase.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that it is a nanoeutectic Nb-Si high-temperature remelted alloy with both high strength and room temperature toughness. In terms of atomic percentage, its general chemical formula is Nb-16Si- 20Ti-1ZrC-0.5Sc; in step 1, weigh elemental Si, elemental Ti, ZrC, elemental Sc and elemental Nb according to the proportion of atomic percentages of 16% Si, 20% Ti, 1% ZrC, 0.5% Sc and 62.5% Nb. ; Step 4: Use a beam current of 25mA to remelt the preheated metal plate at a moving speed of 400mm/min. Others are the same as Embodiment 1.

Figure 3 is a microstructure diagram of the Nb-16Si-20Ti-1ZrC-0.5Sc remelted alloy prepared in Example 3; it can be seen from the figure that the structure of the Nb-16Si-20Ti-1ZrC-0.5Sc remelted alloy in Example 3 is fine, and is a dendrite morphology structure of two-phase composite growth. The size of the Nbss/Nb ₅ Si ₃ eutectic structure phase varies from 400nm to 600nm, and there is no large-sized primary silicide phase.

Under the condition that the loading rate is 0.2mm/min, the room temperature fracture toughness test is carried out on the remelted alloy prepared in Examples 1 to 3, and the room temperature fracture toughness test is carried out on the remelted alloy prepared in Examples 1 to 3 under the condition of loading rate 0.5mm/min. Compressive strength test; under the condition that the loading rate is 0.5mm/min, the remelted alloy prepared in Examples 1 to 3 was subjected to a 1200°C compressive strength test; Figure 4 shows the room temperature fracture of the remelted Nb-Si alloy prepared in Examples 1 to 3 Toughness diagram; Figure 5 is a room temperature compressive strength diagram of the remelted Nb-Si alloy prepared in Examples 1 to 3; Figure 6 is a high temperature (1200°C) compressive strength diagram of the remelted Nb-Si alloy prepared in Examples 1 to 3. The room temperature fracture toughness of the remelted Nb-Si alloy prepared in Example 1 is 22.6MPa·m ^{1 /2} , the room temperature compressive strength is 2241MPa, and the high temperature compressive strength is 391MPa. The room temperature fracture toughness of the remelted Nb-Si alloy prepared in Example 2 is 28.6MPa·m ^1/2 , the room temperature compressive strength is 2355MPa, and the high temperature compressive strength is 428MPa. The room temperature fracture toughness of the remelted Nb-Si alloy prepared in Example 3 is 39.1MPa·m ^1/2 , the room temperature compressive strength is 2757MPa, and the high temperature compressive strength is 456MPa. In summary, the nanoeutectic Nb-Si superalloy prepared by electron beam remelting in Examples 1 to 3 has both strength and toughness and excellent mechanical properties. It can be seen from Figures 4 to 6 that as the electron beam scanning rate increases, the room temperature fracture toughness, room temperature and high temperature compressive strength gradually increase.

Claims (9)

1. A nano eutectic Nb-Si high temperature remelting alloy with high strength and room temperature toughness is characterized in that according to atomic percent, the chemical formula of the alloy is Nb-16Si-20Ti-1ZrC-xSc, wherein x is 0.02-0.5;

the preparation method of the nano eutectic Nb-Si high-temperature remelted alloy with high strength and room temperature toughness comprises the following steps:

1. weighing simple substance Si, simple substance Ti, zrC, simple substance Sc and simple substance Nb according to the proportion of 16% Si, 20% Ti, 1% ZrC, x% Sc and 63-x% Nb by atomic percentage to obtain a weighed raw material; x is 0.02-0.5;

2. sequentially placing the weighed raw materials into a smelting chamber from bottom to top according to the particle size from small to large, and smelting in an argon atmosphere to obtain an ingot;

3. cutting the cast ingot into plates, polishing to remove linear cutting marks, and finally cleaning to obtain a metal plate;

4. fixing a metal plate on an electron beam deposition chamber platform, vacuumizing, introducing protective argon, preheating the metal plate by using a beam current of 10 mA-15 mA, remelting the preheated metal plate by using a beam current of 24 mA-26 mA under the condition that the moving speed is 100 mm/min-400 mm/min, and finally cooling along with a furnace to obtain the nano eutectic Nb-Si high-temperature remelting alloy with high strength and room temperature toughness.

2. The nano eutectic Nb-Si high temperature remelted alloy with high strength and room temperature toughness according to claim 1, wherein the argon atmosphere in the second step is specifically introduced as follows: firstly, vacuumizing a smelting chamber to 10 Pa-20 Pa, then introducing protective argon for 10 s-20 s, repeating vacuumizing and argon introducing for three times, and vacuumizing to 3X 10 ^{- 3} Pa～4×10 ^-3 Pa, and finally introducing protective argon to 400-500 Pa.

3. The nano eutectic Nb-Si high temperature remelted alloy with both high strength and room temperature toughness according to claim 1, wherein in step two, melting is performed under an argon atmosphere and a current of 600A.

4. The nano eutectic Nb-Si high temperature remelted alloy having both high strength and room temperature toughness according to claim 3 wherein the melting is repeated 6 to 7 times in the argon atmosphere in the second step.

5. The nano eutectic Nb-Si high-temperature remelting alloy with high strength and room temperature toughness according to claim 4, wherein in the second step, the weighed raw materials are sequentially placed in a smelting chamber from bottom to top according to the particle size, elemental Ti is smelted first in an argon atmosphere, and then other weighed raw materials are smelted to obtain an ingot.

6. The nano eutectic Nb-Si high temperature remelted alloy with high strength and room temperature toughness according to claim 1, wherein in the third step, 800# water-based abrasive paper is used for polishing to remove linear cutting traces, and finally alcohol is used for cleaning.

7. The nano eutectic Nb-Si high temperature remelted alloy with high strength and room temperature toughness as set forth in claim 1, wherein the vacuum is applied to 3×10 in the fourth step ^-3 Pa～4×10 ^-3 Pa, and then introducing protective argon to 200-500 Pa.

8. The nano eutectic Nb-Si high temperature remelting alloy with high strength and room temperature toughness according to claim 1, wherein in the fourth step, the preheated metal plate is remelted by using a beam current of 25mA under the condition that the moving speed is 100 mm/min-400 mm/min.

9. The nano eutectic Nb-Si high temperature remelting alloy with both high strength and room temperature toughness according to claim 1, wherein in the fourth step, the preheated metal plate is remelted with a beam current of 25mA at a moving speed of 400 mm/min.