CN108085528B - A method for in-situ endogenous nano-NbB2 particle refinement and strengthening of aluminum alloy - Google Patents

Abstract

The present invention relates to a kind of method for in-situ endogenous nano _- NbB particle refinement and strengthening of aluminum alloy, specifically comprising the following four steps: (1) in-situ endogenous nano _- NbB particle refinement and preparation of a strengthening agent; ( 2) Preparation of unrefined and strengthened aluminum alloys; (3) Strengthened aluminum alloys with endogenous nano-NbB ₂ ceramic particles; this technical method has high refining and strengthening efficiency, and is easy to operate. Microstructure refinement and performance enhancement of aluminum alloys. After the aluminum alloy was refined and strengthened, the ɑ-Al dendrites were significantly refined, and the mechanical properties of the alloy were significantly improved: the yield strength, tensile strength and plasticity were significantly improved; the addition of a small amount of nano _- NbB particles Good results can be achieved, and the application field of the refined and strengthened aluminum alloy is further expanded, which provides a new solution for the thin-walled and lightweight aluminum alloy, which has important practical application value.

Description

A method for in-situ endogenous nano-NbB2 particle refinement and strengthening of aluminum alloy

technical field

The invention relates to the field of aluminum alloy processing and preparation, in particular to a method for refining and strengthening aluminum alloys by in-situ endogenous nano-NbB ₂ particles.

Background technique

In order to reduce energy consumption and reduce environmental pollution, reducing the weight of structural parts and enhancing the mechanical properties of materials have promoted the development of lightweight industries such as automobiles and aerospace, among which aluminum alloys have played a key role. Aluminum alloy is a material that is easy to form, low density, high specific strength and good corrosion resistance, and is widely used in the manufacture of parts required in the transportation industry. In recent years, how to further improve the physical, chemical, mechanical and other properties of aluminum alloy materials has become the first problem that researchers consider. As we all know, grain refinement is the key to improving the mechanical properties of materials, usually by adding refiners and strengthening agents containing ceramic particles to achieve grain refinement and material strengthening. As a transition metal boride, NbB ₂ has the characteristics of high melting point, high hardness, good corrosion resistance and other high temperature mechanical properties. NbB ₂ and the aluminum alloy matrix with a face-centered cubic crystal structure have a low degree of lattice mismatch, and the niobium-silicon compound is a high-temperature intermetallic compound with a high melting point and good chemical stability. The experimental results show that the solid solubility of Si in AlNb ₃ and AlNb ₂ is small, and the solid solubility in Al ₃ Nb is only 2 at.%. At 800 °C, the formation of niobium-silicon compounds in the aluminum melt is less likely. Therefore, the Nb-containing phase can be used as a heterogeneous nucleating agent for the refinement of aluminum-silicon alloys without the poisoning effect of Si. In addition, the small size and large number of NbB ₂ nanoparticles can serve as the substrate for the heteronucleation of α-Al and promote the heteronucleation of α-Al. The unnucleated nanoparticles can also be adsorbed on the solid-liquid interface at the front of the dendrite growth to form a nanoparticle layer, which hinders the transfer of solute atoms to the solidification front of the solid-liquid interface, hinders the growth of dendrites, and significantly refines the grains of aluminum alloys. The in-situ endogenous NbB ₂ nanoparticles are uniformly dispersed in the aluminum alloy matrix and have less agglomeration. The nanoparticles strengthen the aluminum alloy through fine grain strengthening, Orovan strengthening, pinning grain boundaries, thermal mismatch strengthening, etc. Yield strength, tensile strength and plasticity are significantly improved. In summary, in-situ endogenous NbB ₂ nanoparticles, as a refining and strengthening agent for aluminum alloys, can be used for the refining and strengthening of aluminum alloys, especially for high-silicon aluminum alloys. , high temperature performance, and resistance to impact load, fatigue resistance, creep resistance and other properties play an important role. The application field of the strengthened aluminum alloy is further expanded. This method has high practical application value and simple operation. The application of a small amount of in-situ endogenous NbB ₂ nanoparticles can obtain a better strengthening effect, which is a thin-walled and lightweight aluminum alloy. An important solution is provided.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for in-situ endogenous nano-NbB ₂ particle refinement and strengthening of aluminum alloys.

The object of the present invention can be realized through the following technical solutions:

A method for in-situ endogenous nano _- NbB particle refinement and strengthening of aluminum alloy, comprising the following steps:

(1) Preparation of in-situ endogenous nano-NbB ₂ particle refinement and strengthening agent:

(1a) Activation pretreatment of boron powder ball milling: put the boron powder into the ball milling tank, and use a ball mill to ball mill the boron powder at a speed of 200～300r/min for 1～3h;

(1b) Preparation of powders for the reaction compact: Weigh the required aluminum powder with a particle size of 13 to 48 μm, boron powder with a particle size of 0.5 to 1 μm after ball milling, niobium powder with a particle size of 48 μm, and copper powder with a particle size of 45 μm. Standby; aluminum powder, niobium powder, boron powder, and copper powder are prepared into 100g mixed powders according to the following ratios to make Al-Nb-B-Cu compacts; the mass ratio of Nb/B is 4.30:1, mol The ratio is 1:2; the content of aluminum powder is 60-90wt.%; the content of niobium powder is 8.11-32.45wt.%; the content of boron powder is 1.89-7.55wt.%; the content of Cu powder is 0-5wt.%, details as follows:

①The mass fraction of nano-NbB ₂ ceramic particles formed by the reaction in the Al-Nb-B system is 10wt.%; the respective weights of aluminum powder, niobium powder, boron powder and copper powder in the system are: aluminum powder: 90 g; niobium powder: 8.11 g; boron powder: 1.89 g; copper powder: 0 g; prepared into 100 g mixed powder; wherein, the Nb/B mass ratio in the nano-NbB ₂ ceramic particles is 4.30:1; the Nb/B molar ratio is 1:2;

②The mass fraction of nano-NbB ₂ ceramic particles produced by the reaction in the Al-Nb-B system is 20wt.%; the respective weights of aluminum powder, niobium powder, boron powder and copper powder in the system are: aluminum powder: 80 g; niobium powder: 16.22 g; boron powder: 3.78 g; copper powder: 0 g; prepared into 100 g mixed powder; wherein, the Nb/B mass ratio in the nano-NbB ₂ ceramic particles is 4.30:1; the Nb/B molar ratio is 1:2;

③ The mass fraction of nano-NbB ₂ ceramic particles produced by the reaction in the Al-Nb-B system is 30wt.%; the respective weights of aluminum powder, niobium powder, boron powder and copper powder in the system are: aluminum powder: 70 grams; niobium powder: 24.33 g; boron powder: 5.67 g; copper powder: 0 g; prepared into 100 g mixed powder; wherein, the Nb/B mass ratio in the nano-NbB ₂ ceramic particles is 4.30:1; the Nb/B molar ratio is 1:2;

④ The mass fraction of nano-NbB ₂ ceramic particles formed by the reaction in the Al-Nb-B system is 40wt.%; the respective weights of aluminum powder, niobium powder, boron powder and copper powder in the system are: aluminum powder: 60 g; niobium powder: 32.45 g g; boron powder: 7.55 g; copper powder: 0 g; formulated into 100 g mixed powder; wherein, the Nb/B mass ratio in the nano-NbB ₂ ceramic particles is 4.30:1; the Nb/B molar ratio is 1:2;

⑤ The mass fraction of nano-NbB ₂ ceramic particles produced by the reaction in the Al-Nb-B-Cu system is 30wt.%, of which the content of Cu element is 5wt.%; the respective weights of aluminum powder, niobium powder, boron powder and copper powder in the system are respectively It is: aluminum powder: 65 grams; niobium powder: 24.33 grams; boron powder: 5.67 grams; copper powder: 5 grams; formulated into 100 grams of mixed powder; wherein, the Nb/B mass ratio in the nano-NbB ₂ ceramic particles is 4.30: 1; Nb/B molar ratio is 1:2;

(1c) Ball milling mixing treatment of the powder used in the reaction compact: put the prepared mixed powder and zirconia grinding balls of different components into the mixer, and the tank contains diameters of 5mm, 7mm, 11mm, ZrO ₂ balls of 15mm, 20mm and 22mm, 10 of each, the total mass of ZrO ₂ balls is 800g; the mixer is uniformly mixed at a speed of 30-60r/min for 8-32h; the mass ratio of zirconia grinding balls to mixed powder is 8:1;

(1d) Preparation of reaction compact: take out the powder mixed by ball milling, wrap the powder mixed by ball milling with aluminum foil, and cold-press on a hydraulic press to make a Φ30 cylindrical compact with a height of 35-45 mm; the density is 60～75%;

(1e) Nanoparticle in situ reaction:

① Wrap the Φ30 cylindrical compact prepared in step (2) with graphite paper and put it into a graphite mold;

②Put the graphite mold and Φ30 cylindrical compact into the vacuum thermal explosion furnace, close the furnace door, and then vacuumize until the pressure in the furnace is lower than 10Pa;

③Start heating, set the heating speed to 25~40K/min; heat up to 1183K, then lower the temperature to 1073K and keep for 10min. During the insulation process, apply axial pressure of 25~55MPa to the cylindrical compact, and hold the pressure for 20 minutes. ~60s; after the reaction, the cylindrical ceramic-aluminum composite densified by axial pressure is cooled to room temperature in vacuum with the furnace;

(2) Preparation of unrefined and strengthened aluminum alloys:

(2a) Place the pre-weighed aluminum alloy in the crucible and put it into the crucible resistance melting furnace together with the crucible, and heat up to 1023K; the composition of the aluminum alloy is: Al-Si ₇ -Mn _0.65 -Mg _0.33 , Al -Si ₁₀ -Cu-Mg _0.39 ;

(2b) After the alloy is completely melted and kept for 30 minutes, 0.05-0.10 wt.% of a slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3) Endogenous nano-NbB ₂ ceramic particles strengthen the aluminum alloy:

(3a) after putting the weighed alloy into the crucible and putting it into the furnace together with the crucible, the temperature is raised to 1123K;

(3b) After the alloy is completely melted and kept for 30 minutes, 0.05-0.10 wt.% of a slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3c) Add the strengthening agent containing NbB ₂ ceramic particles into the alloy liquid, the actual addition amount of NbB ₂ ceramic particles is 0.1wt.%~0.3wt.%, and ultrasonically treat the mixed alloy liquid for 3~10min _; The mass ratio of Nb/B in the ceramic particles is 4.30:1; the molar ratio of Nb/B is 1:2;

(3d) The molten metal after ultrasonic treatment is cast into a metal mold, and after solidification and cooling, a plate-like pattern of nano-NbB ₂ ceramic particles refined and strengthened aluminum alloy is obtained.

Preferably, the material of the metal mold in step (3d) is: 45# steel, and the size of the metal mold is: 200mm×150mm×20mm.

The microstructure and mechanical properties of the material are obviously optimized: under the optimal refining and strengthening conditions (the addition of NbB ceramic particles in the Al _- 7Si-0.65Mn-0.33Mg alloy is 0.1 wt.%, The grains of Nb/B=1:2) aluminum alloys have been significantly refined, and the as-cast yield strength, tensile strength and fracture strain of the alloy are 168.7MPa, 255.2MPa, and 8.6%, respectively. The yield strength, tensile strength and fracture strain of the as-cast aluminum alloy without refining and strengthening treatment are 143.9MPa, 205.0MPa, and 6.0%, respectively. After refining and strengthening the aluminum alloy by adding NbB ₂ nanoparticles, the yield strength, tensile strength, and fracture strain of the alloy are increased by 17.2%, 24.5%, and 43.3%, respectively, compared with the untreated alloy, and the mechanical properties are significantly improved. .

Beneficial effects of the invention: a method for in-situ endogenous nano _- NbB particle refinement and strengthening of aluminum alloys in the present invention, specifically comprising the following four steps: (1) in-situ endogenous nano _- NbB particle refinement and Preparation of strengthening agent; (2) preparation of unrefined and strengthened aluminum alloy; (3) strengthened treatment of aluminum alloy with endogenous nano-NbB ₂ ceramic particles; the technical method has high refining and strengthening efficiency, and is easy to operate, especially It is suitable for microstructure refinement and performance enhancement of aluminum alloys with high silicon content. After the aluminum alloy was refined and strengthened, the α-Al dendrites were significantly refined, and the mechanical properties of the alloy were significantly improved: the yield strength, tensile strength and plasticity were significantly improved; the addition of a small amount of nano _- NbB particles Good results can be achieved, and the application field of the refined and strengthened aluminum alloy is further expanded, which provides a new solution for the thin-walled and lightweight aluminum alloy, which has important practical application value.

Description of drawings

Fig. 1 is the as-cast grain structure diagram of Al-Si ₇ -Mn _0.65 -Mg _0.33 aluminum alloy without refining and strengthening treatment.

Figure 2 is the as-cast grain structure diagram of the Al-Si ₁₀ -Cu-Mg _0.39 aluminum alloy that has not been refined and strengthened.

FIG. 3 is the as-cast grain structure diagram of the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.1 wt. % NbB ₂ ceramic particles in Example 1. FIG.

4 is the tensile stress-strain curve of the as-cast Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.1 wt. % NbB ₂ ceramic particles in Example 1. FIG.

FIG. 5 is the as-cast grain structure diagram of the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.1 wt. % NbB ₂ ceramic particles in Example 2. FIG.

FIG. 6 is the tensile stress-strain curve of the as-cast Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.1 wt. % NbB ₂ ceramic particles in Example 2. FIG.

7 is the as-cast grain structure diagram of the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.3 wt. % NbB ₂ ceramic particles in Example 3. FIG.

8 is the tensile stress-strain curve of the as-cast Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.3 wt. % NbB ₂ ceramic particles in Example 3. FIG.

9 is the as-cast grain structure diagram of the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.3 wt. % NbB ₂ ceramic particles in Example 4. FIG.

10 is the tensile stress-strain curve of the as-cast Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.3 wt. % NbB ₂ ceramic particles in Example 4. FIG.

11 is the as-cast grain structure diagram of the Al-Si ₁₀ -Cu-Mg _0.39 alloy added with 0.3 wt. % NbB ₂ ceramic particles in Example 5. FIG.

12 is the tensile stress-strain curve of the as-cast Al-Si ₁₀ -Cu-Mg _0.39 alloy added with 0.3 wt. % NbB ₂ ceramic particles in Example 5. FIG.

Detailed ways

In order to make the technical means, innovative features, and goals achieved by the present invention easy to understand, the present invention will be further described below with reference to the specific embodiments.

Example 1:

A method for in-situ endogenous nano-NbB ₂ particle refinement and strengthening of aluminum alloys in this embodiment includes the following steps:

(1) Preparation of in-situ endogenous nano-NbB ₂ particle refinement and strengthening agent:

(1a) Activation pretreatment of boron powder ball milling: put the boron powder into the ball mill tank, and use a ball mill to ball mill the boron powder for activation treatment at a speed of 200r/min for 3h;

(1b) Preparation of powder for reaction compact: Weigh a certain amount of required aluminum powder with a particle size of 25 μm, ball-milled boron powder with a particle size of 0.5 μm, and niobium powder with a particle size of 48 μm for use. The aluminum powder, niobium powder and boron powder are prepared into 100g mixed powder according to the following ratios to make Al-Nb-B compact. Among them, the mass fraction of nano-NbB ₂ ceramic particles (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1:2) produced by the reaction in the Al-Nb-B system is 10wt.%: aluminum powder, niobium powder in the system The respective weights of powder and boron powder are: aluminum powder: 90 grams; niobium powder: 8.11 grams; boron powder: 1.89 grams; prepared into 100 grams of mixed powder;

(1c) Ball milling mixing treatment of the powder used in the reaction compact: put the prepared mixed powder and zirconia grinding balls of different components into the mixer, and the tank contains diameters of 5mm, 7mm, 11mm, ZrO ₂ balls of 15mm, 20mm and 22mm, 10 of each, the total mass of ZrO ₂ balls is 800g. The mixer is uniformly mixed for 32h at a speed of 30r/min; the mass ratio of zirconia grinding balls and mixed powder is 8:1;

(1d) Preparation of reaction compact: take out the powder mixed by ball milling, wrap the powder mixed by ball milling with aluminum foil, and cold-press on a hydraulic press to make a cylindrical compact of Φ30 with a height of 40 mm; the density is 70% ;

(1e) Nanoparticle in situ reaction:

① Wrap the Φ30 cylindrical compact prepared in step (2) with graphite paper and put it into a graphite mold;

②Put the graphite mold and Φ30 cylindrical compact into the vacuum thermal explosion furnace, close the furnace door, and then vacuumize until the pressure in the furnace is lower than 10Pa;

③ Start heating, and set the heating speed to 35K/min; heat up to 1183K, then lower the temperature to 1073K and keep it for 10min. During the heat preservation process, apply an axial pressure of 45MPa to the cylindrical compact, and keep the pressure for 25s; The cylindrical ceramic-aluminum composite densified by axial pressure is cooled to room temperature in vacuum in a furnace;

(2) Preparation of unrefined and strengthened aluminum alloys:

(2a) place the aluminum alloy weighed in advance in the crucible and put into the crucible resistance melting furnace together with the crucible, and be heated to 1023K; the composition of the aluminum alloy is: Al-Si ₇ -Mn _0.65 -Mg _0.33 ;

(2b) After the alloy is completely melted and kept for 30 minutes, 0.05wt.% slag removal agent is added to refine and remove slag from the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3) step 3, endogenous nano-NbB ₂ ceramic particles strengthen the aluminum alloy:

(3a) after putting the weighed alloy into the crucible and putting it into the furnace together with the crucible, the temperature is raised to 1123K;

(3b) After the alloy is completely melted and kept for 30 minutes, 0.05wt.% of a slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3c) _The strengthening agent containing NbB ceramic particles is added to the alloy liquid, and the actual addition amount of _NbB ceramic particles is 0.1 wt.% (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1: 2), the mixed alloy liquid is ultrasonically treated for 3min;

(3d) The molten metal after ultrasonic treatment is cast into a metal mold, and after solidification and cooling, a plate-like pattern of nano-NbB ₂ ceramic particles refined and strengthened aluminum alloy is obtained.

Wherein, the material of the metal mold in step (3d) is: 45# steel, and the size of the metal mold is: 200mm×150mm×20mm.

In situ endogenous nano-NbB ₂ ceramic particles can be used as an effective refiner and strengthening agent for aluminum alloys. FIG. 3 is the as-cast grain structure diagram when the addition amount of NbB ₂ ceramic particles is 0.1 wt. % in the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy. Compared with the unrefined aluminum alloy structure (as shown in Figure 1), the aluminum alloy grains added with nanoparticles are refined. FIG. 4 is the tensile stress-strain curve of the as-cast Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.1 wt. % NbB ₂ ceramic particles. After adding NbB ₂ nanoparticles, the as-cast yield strength σ _0.2 (MPa) of the aluminum alloy is 163.2 MPa, the tensile strength UTS (MPa) is 238.0 MPa, and the fracture strain ε _f (%) is 8.8%. Compared with the tensile properties of the aluminum alloy without refining and strengthening treatment (yield strength: 143.9MPa, tensile strength: 205.0MPa, fracture strain: 6.0%), the yield strength, tensile strength of the aluminum alloy with _NbB nanoparticles added The strength and fracture strain were increased by 13.4%, 16.1%, and 46.7%, respectively, and the mechanical properties were significantly improved, as shown in Figure 4 and Table 1.

Example 2:

A method for in-situ endogenous nano-NbB ₂ particle refinement and strengthening of aluminum alloys in this embodiment includes the following steps:

(1) Preparation of in-situ endogenous nano-NbB ₂ particle refinement and strengthening agent:

(1a) Activation pretreatment of boron powder ball milling: put the boron powder into the ball mill tank, and use a ball mill to ball mill the boron powder for activation treatment at a speed of 200r/min for 3h;

(1b) Preparation of powders used in the reaction compact: Weigh a certain amount of required aluminum powder with a particle size of 13 μm, ball-milled boron powder with a particle size of 0.5 μm, and niobium powder with a particle size of 48 μm for use; , Boron powder is prepared into 100g mixed powder according to the following ratios to make Al-Nb-B compact. Among them, the mass fraction of nano-NbB ₂ ceramic particles (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1:2) generated by the reaction in the Al-Nb-B system is 20wt.%: aluminum powder, niobium powder in the system The respective weights of the powder and the boron powder are: aluminum powder: 80 grams; niobium powder: 16.22 grams; boron powder: 3.78 grams; prepared into 100 grams of mixed powder.

(1c) Ball milling mixing treatment of the powder used in the reaction compact: put the prepared mixed powder and zirconia grinding balls of different components into the mixer, and the tank contains diameters of 5mm, 7mm, 11mm, ZrO ₂ balls of 15mm, 20mm and 22mm, 10 of each, the total mass of ZrO ₂ balls is 800g. The mixer is uniformly mixed for 8h at a speed of 60r/min; the mass ratio of zirconia grinding balls and mixed powder is 8:1;

(1d) Preparation of reactive compacts:

Take out the ball-milled powder, wrap the ball-milled powder with aluminum foil, and cold-press on a hydraulic press to make a Φ30 cylindrical compact with a height of 35mm and a density of 75%;

(1e) Nanoparticle in situ reaction:

① Wrap the Φ30 cylindrical compact prepared in step (2) with graphite paper and put it into a graphite mold;

②Put the graphite mold and Φ30 cylindrical compact into the vacuum thermal explosion furnace, close the furnace door, and then vacuumize until the pressure in the furnace is lower than 10Pa;

③Start heating, and set the heating speed to 25K/min; heat up to 1183K, then lower the temperature to 1073K and keep it for 10min. During the heat preservation process, apply an axial pressure of 55MPa to the cylindrical compact, and keep the pressure for 20s; The cylindrical ceramic-aluminum composite densified by axial pressure is cooled to room temperature in vacuum in a furnace;

(2) Preparation of unrefined and strengthened aluminum alloys:

(2a) place the aluminum alloy weighed in advance in the crucible and put into the crucible resistance melting furnace together with the crucible, and be heated to 1023K; the composition of the aluminum alloy is: Al-Si ₇ -Mn _0.65 -Mg _0.33 ;

(2b) After the alloy is completely melted and kept for 30 minutes, 0.10 wt.% slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3) Endogenous nano-NbB ₂ ceramic particles strengthen the aluminum alloy:

(3a) after putting the weighed alloy into the crucible and putting it into the furnace together with the crucible, the temperature is raised to 1123K;

(3b) After the alloy is completely melted and kept for 30 minutes, 0.10wt.% slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3c) _The strengthening agent containing NbB ceramic particles is added to the alloy liquid, and the actual addition amount of _NbB ceramic particles is 0.1 wt.% (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1: 2), the mixed alloy liquid is ultrasonically treated for 5min;

(3d) The molten metal after ultrasonic treatment is cast into a metal mold, and after solidification and cooling, a plate-like pattern of nano-NbB ₂ ceramic particles refined and strengthened aluminum alloy is obtained.

Wherein, the material of the metal mold in step (3d) is: 45# steel, and the size of the metal mold is: 200mm×150mm×20mm.

In situ endogenous nano-NbB ₂ ceramic particles can be used as an effective refiner and strengthening agent for aluminum alloys. FIG. 5 is the as-cast grain structure diagram when the addition amount of NbB ₂ ceramic particles is 0.1 wt. % in the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy. Compared with the unrefined aluminum alloy structure (as shown in Figure 1), the aluminum alloy grains added with nanoparticles are refined. FIG. 6 is a tensile stress-strain curve of the as-cast Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy added with 0.1 wt. % NbB ₂ ceramic particles. After adding NbB ₂ nanoparticles, the as-cast yield strength σ _0.2 (MPa) of the aluminum alloy is 168.7 MPa, the tensile strength UTS (MPa) is 255.2 MPa, and the fracture strain ε _f (%) is 8.6%. Compared with the tensile properties of the aluminum alloy without refining and strengthening treatment (yield strength: 143.9MPa, tensile strength: 205.0MPa, fracture strain: 6.0%), the yield strength, tensile strength of the aluminum alloy with _NbB nanoparticles added The strength and fracture strain were increased by 17.2%, 24.5%, and 43.3%, respectively, and the mechanical properties were significantly improved, as shown in Figure 6 and Table 1.

Example 3:

A method for in-situ endogenous nano-NbB ₂ particle refinement and strengthening of aluminum alloys in this embodiment includes the following steps:

(1) Preparation of in-situ endogenous nano-NbB ₂ particle refinement and strengthening agent:

(1a) Activation pretreatment of boron powder ball milling: put the boron powder into the ball mill tank, and use a ball mill to ball mill the boron powder for activation treatment at a speed of 200r/min for 3h;

(1b) Preparation of powders for the reaction compact: Weigh a certain amount of required aluminum powder with a particle size of 25 μm, boron powder with a particle size of 0.5 μm after ball milling, niobium powder with a particle size of 48 μm, and copper powder with a particle size of 48 μm for use ; The aluminum powder, niobium powder, boron powder and copper powder are prepared into 100g mixed powder according to the following ratios to make Al-Nb-B-Cu compact. Among them, the mass fraction of nano-NbB ₂ ceramic particles (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1:2) in the Al-Nb-B-Cu system is 30wt.%, of which the Cu element is The content is 5wt.%: the respective weights of aluminum powder, niobium powder, boron powder and copper powder in the system are: aluminum powder: 65 grams; niobium powder: 24.33 grams; boron powder: 5.67 grams; copper powder: 5 grams; 100 g mixed powder;

(1c) Ball milling mixing treatment of the powder used in the reaction compact: put the prepared mixed powder and zirconia grinding balls of different components into the mixer, and the tank contains diameters of 5mm, 7mm, 11mm, ZrO ₂ balls of 15mm, 20mm and 22mm, 10 of each, the total mass of ZrO ₂ balls is 800g. The mixer is uniformly mixed for 20h at a speed of 45r/min; the mass ratio of zirconia grinding balls and mixed powder is 8:1;

(1d) Preparation of reaction compact: take out the powder mixed by ball milling, wrap the powder mixed by ball milling with aluminum foil, and cold-press on a hydraulic press to make a cylindrical compact of Φ30 with a height of 35 mm; the density is 75% ;

(1e) Nanoparticle in situ reaction:

① Wrap the Φ30 cylindrical compact prepared in step (2) with graphite paper and put it into a graphite mold;

②Put the graphite mold and Φ30 cylindrical compact into the vacuum thermal explosion furnace, close the furnace door, and then vacuumize until the pressure in the furnace is lower than 10Pa;

③Start heating, and set the heating speed to 40K/min; heat up to 1183K, then lower the temperature to 1073K and keep it for 10min. During the heating process, apply an axial pressure of 30MPa to the cylindrical compact for 55s; The cylindrical ceramic-aluminum composite densified by axial pressure is cooled to room temperature in vacuum in a furnace;

(2) Preparation of unrefined and strengthened aluminum alloys:

(2a) The pre-weighed aluminum alloy is placed in the crucible and put into the crucible resistance melting furnace together with the crucible, and the temperature is raised to 1023K; the composition of the aluminum alloy is: Al-Si ₇ -Mn _0.65 -Mg _0.33 .

(2b) After the alloy is completely melted and kept for 30 minutes, 0.05wt.% slag removal agent is added to refine and remove slag from the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3) Endogenous nano-NbB ₂ ceramic particles strengthen the aluminum alloy:

(3a) after putting the weighed alloy into the crucible and putting it into the furnace together with the crucible, the temperature is raised to 1123K;

(3b) After the alloy is completely melted and kept for 30 minutes, 0.05wt.% of a slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3c) _The strengthening agent containing NbB ceramic particles is added to the alloy liquid, and the actual addition amount of _NbB ceramic particles is 0.3 wt.% (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1: 2), the mixed alloy liquid is ultrasonically treated for 8min;

(3d) The molten metal after ultrasonic treatment is cast into a metal mold, and after solidification and cooling, a plate-like pattern of nano-NbB ₂ ceramic particles refined and strengthened aluminum alloy is obtained.

Wherein, the material of the metal mold in step (3d) is: 45# steel, and the size of the metal mold is: 200mm×150mm×20mm.

In situ endogenous nano-NbB ₂ ceramic particles can be used as an effective refiner and strengthening agent for aluminum alloys. FIG. 7 is the as-cast grain structure diagram of the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy when the addition amount of NbB ₂ ceramic particles is 0.3 wt. %. Compared with the unrefined aluminum alloy structure (as shown in Figure 1), the aluminum alloy grains added with nanoparticles are refined. Figure 8 is a tensile stress-strain curve of the as-cast Al-Si7- _{Mn0.65 - Mg0.33} alloy with 0.3 wt.% _NbB2 ceramic particles added. After adding NbB ₂ nanoparticles, the as-cast yield strength σ _0.2 (MPa) of the aluminum alloy is 156.8 MPa, the tensile strength UTS (MPa) is 225.8 MPa, and the fracture strain ε _f (%) is 10.1%. Compared with the tensile properties of the aluminum alloy without refining and strengthening treatment (yield strength: 143.9MPa, tensile strength: 205.0MPa, fracture strain: 6.0%), the yield strength and tensile strength of the aluminum alloy with _NbB nanoparticles added The strength and fracture strain were increased by 9.0%, 10.2%, and 68.3%, respectively, and the mechanical properties were significantly improved, as shown in Figure 8 and Table 1.

Example 4:

A method for in-situ endogenous nano-NbB ₂ particle refinement and strengthening of aluminum alloys in this embodiment includes the following steps:

(1) Preparation of in-situ endogenous nano-NbB ₂ particle refinement and strengthening agent:

(1a) Activation pretreatment of boron powder ball milling: put the boron powder into the ball milling tank, and use a ball mill to ball mill the boron powder for activation treatment at a speed of 300r/min for 1h;

(1b) Preparation of powder used in the reaction compact: Weigh a certain amount of required aluminum powder with a particle size of 48 μm, ball-milled boron powder with a particle size of 1 μm, and niobium powder with a particle size of 48 μm for use. The aluminum powder, niobium powder and boron powder are prepared into 100g mixed powder according to the following ratios to make Al-Nb-B compact. Among them, the mass fraction of nano-NbB ₂ ceramic particles (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1:2) produced by the reaction in the Al-Nb-B system is 30 wt.%: aluminum powder, niobium powder in the system The respective weights of powder and boron powder are: aluminum powder: 70 grams; niobium powder: 24.33 grams; boron powder: 5.67 grams; prepared into 100 grams of mixed powder;

(1c) Ball milling mixing treatment of the powder used in the reaction compact:

Put the prepared mixed powders of different components and zirconia grinding balls into the mixer, and the tank contains ZrO ₂ balls with diameters of 5mm, 7mm, 11mm, 15mm, 20mm, and 22mm, 10 of each type. , the mass of ZrO ₂ ball is 800g in total. The mixer is uniformly mixed for 25h at a speed of 40/min; the mass ratio of zirconia grinding balls and mixed powder is 8:1;

(1d) Preparation of reactive compacts:

Take out the ball-milled powder, wrap the ball-milled powder with aluminum foil, and cold-press on a hydraulic press to make a Φ30 cylindrical compact with a height of 35mm and a density of 75%;

(1e) Nanoparticle in situ reaction:

① Wrap the Φ30 cylindrical compact prepared in step (2) with graphite paper and put it into a graphite mold;

②Put the graphite mold and Φ30 cylindrical compact into the vacuum thermal explosion furnace, close the furnace door, and then vacuumize until the pressure in the furnace is lower than 10Pa;

③Start heating and set the heating speed to 30K/min; heat up to 1183K, then lower the temperature to 1073K and keep it for 10min. During the heat preservation process, apply an axial pressure of 25MPa to the cylindrical compact for 60s; The cylindrical ceramic-aluminum composite densified by axial pressure is cooled to room temperature in vacuum in a furnace;

(2) Preparation of unrefined and strengthened aluminum alloys:

(2a) place the aluminum alloy weighed in advance in the crucible and put into the crucible resistance melting furnace together with the crucible, and be heated to 1023K; the composition of the aluminum alloy is: Al-Si ₇ -Mn _0.65 -Mg _0.33 ;

(2b) After the alloy is completely melted and kept for 30 minutes, 0.05wt.% slag removal agent is added to refine and remove slag from the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3) Endogenous nano-NbB ₂ ceramic particles strengthen the aluminum alloy:

(3a) after putting the weighed alloy into the crucible and putting it into the furnace together with the crucible, the temperature is raised to 1123K;

(3b) After the alloy is completely melted and kept for 30 minutes, 0.05wt.% of a slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3c) _The strengthening agent containing NbB ceramic particles is added to the alloy liquid, and the actual addition amount of _NbB ceramic particles is 0.3 wt.% (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1: 2), the mixed alloy liquid is ultrasonically treated for 10min;

(3d) The molten metal after ultrasonic treatment is cast into a metal mold, and after solidification and cooling, a plate-like pattern of nano-NbB ₂ ceramic particles refined and strengthened aluminum alloy is obtained.

Wherein, the material of the metal mold in step (3d) is: 45# steel, and the size of the metal mold is: 200mm×150mm×20mm.

In situ endogenous nano-NbB ₂ ceramic particles can be used as an effective refiner and strengthening agent for aluminum alloys. FIG. 9 is the as-cast grain structure diagram when the addition amount of NbB ₂ ceramic particles is 0.3 wt. % in the Al-Si ₇ -Mn _0.65 -Mg _0.33 alloy. Compared with the unrefined aluminum alloy structure (as shown in Figure 1), the aluminum alloy grains added with nanoparticles are refined. Figure 10 is the tensile stress-strain curve of the as-cast Al-Si7- _{Mn0.65 - Mg0.33} alloy with 0.3 wt.% _NbB2 ceramic particles added. After adding NbB ₂ nanoparticles, the as-cast yield strength σ _0.2 (MPa) of the aluminum alloy is 152.4 MPa, the tensile strength UTS (MPa) is 218.9 MPa, and the fracture strain ε _f (%) is 10.9%. Compared with the tensile properties of the aluminum alloy without refining and strengthening treatment (yield strength: 143.9MPa, tensile strength: 205.0MPa, fracture strain: 6.0%), the yield strength and tensile strength of the aluminum alloy with _NbB nanoparticles added The strength and fracture strain were increased by 6.0%, 6.3%, and 81.7%, respectively, and the mechanical properties were significantly improved, as shown in Figure 10 and Table 1.

Example 5:

A method for in-situ endogenous nano-NbB ₂ particle refinement and strengthening of aluminum alloys in this embodiment includes the following steps:

(1) Preparation of in-situ endogenous nano-NbB ₂ particle refinement and strengthening agent:

(1a) Activation pretreatment of boron powder ball milling: put the boron powder into the ball milling tank, and use a ball mill to ball mill the boron powder for activation treatment at a speed of 300r/min for 1h;

(1b) Preparation of powder for reaction compact: Weigh a certain amount of required aluminum powder with a particle size of 25 μm, ball-milled boron powder with a particle size of 1 μm, and niobium powder with a particle size of 48 μm for use. The aluminum powder, niobium powder and boron powder are prepared into 100g mixed powder according to the following ratios to make Al-Nb-B compact. Among them, the mass fraction of nano-NbB ₂ ceramic particles (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1:2) produced by the reaction in the Al-Nb-B system is 40wt.%: aluminum powder, niobium powder in the system The respective weights of powder and boron powder are: aluminum powder: 60 grams; niobium powder: 32.45 grams; boron powder: 7.55 grams; prepared into 100 grams of mixed powder;

(1c) Ball milling mixing treatment of the powder used in the reaction compact: put the prepared mixed powder and zirconia grinding balls of different components into the mixer, and the tank contains diameters of 5mm, 7mm, 11mm, ZrO ₂ balls of 15mm, 20mm and 22mm, 10 of each, the total mass of ZrO ₂ balls is 800g. The mixer is uniformly mixed for 20 hours at a speed of 45/min; the mass ratio of zirconia grinding balls and mixed powder is 8:1;

(1d) Preparation of reaction compact: take out the powder mixed by ball milling, wrap the powder mixed by ball milling with aluminum foil, and cold-press on a hydraulic press to make a cylindrical compact of Φ30, with a height of 45 mm; the density is 65% ;

(1e) Nanoparticle in situ reaction:

① Wrap the Φ30 cylindrical compact prepared in step (2) with graphite paper and put it into a graphite mold;

②Put the graphite mold and Φ30 cylindrical compact into the vacuum thermal explosion furnace, close the furnace door, and then vacuumize until the pressure in the furnace is lower than 10Pa;

③ Start heating, and set the heating speed to 40K/min; heat up to 1183K, then lower the temperature to 1073K and keep it for 10min. During the heat preservation process, apply an axial pressure of 35MPa to the cylindrical compact, and hold the pressure for 48s; The cylindrical ceramic-aluminum composite densified by axial pressure is cooled to room temperature in vacuum in a furnace;

(2) Preparation of unrefined and strengthened aluminum alloys:

(2a) the pre-weighed aluminum alloy is placed in the crucible and put into the crucible resistance melting furnace together with the crucible, and the temperature is raised to 1023K; the composition of the aluminum alloy is: Al-Si ₁₀ -Cu-Mg _0.39 ;

(2b) After the alloy is completely melted and kept for 30 minutes, 0.10 wt.% slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3) Endogenous nano-NbB ₂ ceramic particles strengthen the aluminum alloy:

(3a) after putting the weighed alloy into the crucible and putting it into the furnace together with the crucible, the temperature is raised to 1123K;

(3b) After the alloy is completely melted and kept for 30 minutes, 0.10wt.% slag cleaning agent is added to refine and remove the slag of the alloy liquid, and the temperature is kept for 10 minutes after the slag treatment;

(3c) _The strengthening agent containing NbB ceramic particles is added to the alloy liquid, and the actual addition amount of _NbB ceramic particles is 0.3 wt.% (Nb/B mass ratio is 4.30:1; Nb/B molar ratio is 1: 2), the mixed alloy liquid is ultrasonically treated for 10min;

(3d) The molten metal after ultrasonic treatment is cast into a metal mold, and after solidification and cooling, a plate-like pattern of nano-NbB ₂ ceramic particles refined and strengthened aluminum alloy is obtained.

Wherein, the material of the metal mold in step (3d) is: 45# steel, and the size of the metal mold is: 200mm×150mm×20mm.

In situ endogenous nano-NbB ₂ ceramic particles can be used as an effective refiner and strengthening agent for aluminum alloys. Fig. 11 is the as-cast grain structure diagram when the addition amount of NbB ₂ ceramic particles is 0.3 wt. % in the Al-Si ₁₀ -Cu-Mg _0.39 alloy. Compared with the unrefined aluminum alloy structure (as shown in Figure 2), the aluminum alloy grains added with nanoparticles are refined. Figure 12 is a tensile curve of the as-cast Al-Si ₁₀ -Cu-Mg _0.39 alloy with 0.3 wt. % NbB ₂ ceramic particles added. After adding NbB ₂ nanoparticles, the as-cast yield strength σ _0.2 (MPa) of the aluminum alloy is 141.8 MPa, the tensile strength UTS (MPa) is 279.6 MPa, and the fracture strain ε _f (%) is 14.3%. Compared with the tensile properties of the aluminum alloy without refining and strengthening treatment (yield strength: 141.8MPa, tensile strength: 249.7MPa, fracture strain: 11.7%), after adding _NbB nanoparticles, the tensile strength of the alloy, Compared with the untreated alloy, the fracture strain is increased by 12.0% and 22%, respectively, and the mechanical properties are improved, as shown in Figure 12 and Table 1.

The microstructure and properties of the aluminum alloys were measured for the above-mentioned example materials, and the following data were obtained: Table 1 shows the tensile strength of the alloys under different aluminum alloy substrates, different nano-NbB ₂ ceramic particle addition amounts, and different preparation process parameters in Examples 1-5. elongation value.

Table 1

sample σ_0.2(MPa) UTS(MPa) ε_f(%) Al-7Si-0.65Mn-0.33Mg 143.9 205.0 6.0 Al-10Si-1Cu-0.39Mg 141.8 249.7 11.7 Implementation Example 1 163.2 238.0 8.8 Implementation Example 2 168.7 255.2 8.6 Implementation Example 3 156.8 225.8 10.1 Implementation Example 4 152.4 218.9 10.9 Implementation Example 5 141.8 279.6 14.3

The microstructure and mechanical properties of the material are obviously optimized: under the optimal refining and strengthening conditions (the addition of NbB ceramic particles in the Al _- 7Si-0.65Mn-0.33Mg alloy is 0.1 wt.%, The grains of Nb/B=1:2) aluminum alloys have been significantly refined, and the as-cast yield strength, tensile strength and fracture strain of the alloy are 168.7MPa, 255.2MPa, and 8.6%, respectively. The yield strength, tensile strength and fracture strain of the as-cast aluminum alloy without refining and strengthening treatment are 143.9MPa, 205.0MPa, and 6.0%, respectively. After refining and strengthening the aluminum alloy by adding NbB ₂ nanoparticles, the yield strength, tensile strength, and fracture strain of the alloy are increased by 17.2%, 24.5%, and 43.3%, respectively, compared with the untreated alloy, and the mechanical properties are significantly improved. .

The above are the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made, and these improvements and modifications may also be regarded as It is the protection scope of the present invention.

Claims (2)

1. In-situ generated nano NbB₂The method for grain refining and strengthening the aluminum alloy is characterized by comprising the following steps: the method comprises the following steps:

(1) in-situ nano NbB₂Particle refinement and preparation of a reinforcing agent:

(1a) b, ball milling activation pretreatment of boron powder: putting boron powder into a ball milling tank, and carrying out ball milling activation treatment on the boron powder for 1-3 h at the speed of 200-300 r/min by using a ball mill;

(1b) preparing powder used for a reaction pressed compact: weighing aluminum powder with the required particle size of 13-48 mu m, and performing ball milling treatment on boron powder with the particle size of 0.5-1 mu m, niobium powder with the particle size of 48 mu m and copper powder with the particle size of 45 mu m for later use; the Al-Nb-B-Cu green compact is prepared by preparing 100g of mixed powder from aluminum powder, niobium powder, boron powder and copper powder according to the following mixture ratio:

firstly, reacting in Al-Nb-B system to generate nano NbB₂The mass fraction of ceramic particles was 10 wt.%; the aluminum powder, the niobium powder, the boron powder and the copper powder in the system respectively have the following weight: aluminum powder: 90 g; niobium powder: 8.11 g; boron powder: 1.89 g; copper powder: 0 g; preparing 100g of mixed powder; wherein, the nanometer NbB₂The Nb/B mass ratio in the ceramic particles is 4.30: 1;

② the nano NbB is generated by the reaction in the Al-Nb-B system₂Mass fraction of ceramic particles 20 wt.%; the aluminum powder, the niobium powder, the boron powder and the copper powder in the system respectively have the following weight: aluminum powder: 80 g; niobium powder: 16.22 g; boron powder: 3.78 g; copper powder: 0 g; preparing 100g of mixed powder; wherein, the nanometer NbB₂The Nb/B mass ratio in the ceramic particles is 4.30: 1;

③ reaction in Al-Nb-B system to generate nanometer NbB₂Mass fraction of ceramic particles 30 wt.%; the aluminum powder, the niobium powder, the boron powder and the copper powder in the system respectively have the following weight: aluminum powder: 70 g; niobium powder: 24.33 g; boron powder: 5.67 g; copper powder: 0 g; preparing 100g of mixed powder; wherein, the nanometer NbB₂The Nb/B mass ratio in the ceramic particles is 4.30: 1;

reacting in Al-Nb-B system to generate nano NbB₂Mass fraction of ceramic particles 40 wt.%; the aluminum powder, the niobium powder, the boron powder and the copper powder in the system respectively have the following weight: aluminum powder: 60 g; niobium powder: 32.45 g; boron powder: 7.55 g; copper powder: 0 g; preparing 100g of mixed powder; wherein, the nanometer NbB₂The Nb/B mass ratio in the ceramic particles is 4.30: 1;

reacting in Al-Nb-B-Cu system to generate NbB₂The mass fraction of the ceramic particles was 30 wt.%, wherein the content of Cu element was 5 wt.%; the aluminum powder, the niobium powder, the boron powder and the copper powder in the system respectively have the following weight: aluminum powder: 65 g; niobium powder: 24.33 g; boron powder: 5.67 g; copper powder: 5 g; preparing 100g of mixed powder;

(1c) ball-milling and mixing the powder used for the reaction pressed compact: putting the prepared mixed powder with different components and zirconia grinding balls into a mixer, and filling ZrO with diameters of 5mm, 7mm, 11mm, 15mm, 20mm and 22mm into a tank₂10 balls each of ZrO₂The ball mass is 800 g; uniformly mixing for 8-32 h at the speed of 30-60 r/min by using a mixer; wherein the mass ratio of the zirconia grinding ball to the mixed powder is 8: 1;

(1d) preparation of reaction green compacts: taking out the powder of the ball-milling mixed material, wrapping the powder of the ball-milling mixed material with an aluminum foil, and performing cold pressing on the wrapped powder on a hydraulic press to obtain a phi 30 cylindrical pressed blank with the height of 35-45 mm; the density is 60-75%;

(1e) in-situ reaction of nanoparticles:

wrapping the prepared phi 30 cylindrical pressed blank by graphite paper and putting the wrapped pressed blank into a graphite mold;

secondly, putting the graphite mould and the phi 30 cylindrical pressed blank into a vacuum thermal explosion furnace, closing a furnace door, and vacuumizing until the pressure in the furnace is lower than 10 Pa;

beginning to heat, and setting the heating speed to be 25-40K/min; heating to 1183K, then reducing the temperature to 1073K, preserving the heat for 10min, and applying axial pressure of 25-55 MPa to the cylindrical pressed compact in the heat preservation process for 20-60 s; cooling the cylindrical ceramic-aluminum compound which is densified by axial pressure to room temperature along with the furnace in vacuum after reaction;

(2) preparation of unrefined and strengthened aluminum alloy:

(2a) placing the pre-weighed aluminum alloy into a crucible, placing the crucible and the aluminum alloy into a crucible type resistance smelting furnace, and heating to 1023K; the aluminum alloy comprises the following components: Al-Si₇-Mn_0.65-Mg_0.33、Al-Si₁₀-Cu-Mg_0.39；

(2b) After the alloy is completely melted, preserving heat for 30min, adding 0.05-0.10 wt.% of slag removing agent to refine and remove slag from the alloy liquid, and preserving heat for 10min after slag removal treatment;

(3) in-situ nano NbB₂Strengthening treatment of the ceramic particles on the aluminum alloy:

(3a) after the weighed alloy is put into a crucible and is put into a furnace together with the crucible, the temperature is increased to 1123K;

(3b) after the alloy is completely melted, preserving heat for 30min, adding 0.05-0.10 wt.% of slag removing agent to refine and remove slag from the alloy liquid, and preserving heat for 10min after slag removal treatment;

(3c) will contain NbB₂Adding ceramic particle reinforcer into the alloy liquid, NbB₂The actual adding amount of the ceramic particles is 0.1-0.3 wt%, and the mixed alloy liquid is subjected to ultrasonic treatment for 3-10 min;

(3d) casting the metal liquid after ultrasonic treatment into a metal mold, solidifying and cooling to obtain the nano NbB₂Plate-like patterns of refined and strengthened aluminum alloy of ceramic particles.

2. The in-situ nano NbB as claimed in claim 1₂The method for grain refining and strengthening the aluminum alloy is characterized by comprising the following steps: the metal mold in the step (3d) is made of the following materials: 45# SteelThe size of the metal mold is as follows: 200mm by 150mm by 20 mm.

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