CN112481516B

CN112481516B - Al-Ti-SiC intermediate alloy and preparation method and application thereof

Info

Publication number: CN112481516B
Application number: CN202011331699.1A
Authority: CN
Inventors: 张国伟; 牛经纬; 吕伟泽; 康圆圆; 徐宏; 任晓燕
Original assignee: North University of China
Current assignee: North University of China
Priority date: 2020-11-24
Filing date: 2020-11-24
Publication date: 2022-01-28
Anticipated expiration: 2040-11-24
Also published as: CN112481516A

Abstract

The invention relates to an Al-Ti-SiC intermediate alloy which is prepared by mixing 40-50 wt% of Al powder, 45-55 wt% of Ti powder and 5-15 wt% of nano SiC powder, pressing and molding, performing high-temperature self-propagating combustion to obtain a self-propagating product, adding the self-propagating product into molten aluminum, diluting until the content of Ti element is 5-5.3 wt%, and pouring to obtain the intermediate alloy containing micro-nano TiC/SiC particles. The master alloy is used as a grain refiner for the aluminum alloy material, so that the heterogeneous nucleation capability of the aluminum alloy material can be improved, the grains of the aluminum alloy material are refined, and the comprehensive mechanical property of the aluminum alloy material is improved.

Description

Al-Ti-SiC intermediate alloy and preparation method and application thereof

Technical Field

The invention belongs to the technical field of aluminum alloy preparation, and relates to an intermediate alloy for adding in an aluminum alloy processing process.

Background

The aluminum alloy has high specific strength, strong corrosion resistance, excellent electric and heat conducting properties and high preparation efficiency, and is widely applied to the fields of aviation, aerospace, ships, automobiles, war industry and the like.

The strength of the aluminum alloy subjected to age hardening can be greatly improved, the performance of cast iron can be achieved in certain fields, and the aluminum alloy is an ideal material for replacing steel, casting for replacing forging and equipment light weight. The as-cast grain size of the aluminum alloy has a large effect on the age hardening of the aluminum alloy. The finer the as-cast grains, the higher the hardening of the aluminum alloy after aging.

Therefore, fine grain strengthening is one of the important means for improving the comprehensive mechanical properties of the aluminum alloy material. The grain refiner commonly used for aluminum alloys comprises intermediate alloys such as Al-Ti, Al-Ti-B, Al-Ti-C and the like.

Methods for preparing Al-Ti and Al-Ti-B master alloys include a fluoride salt method, an oxide method, a self-propagating synthesis method, and the like. Among them, the fluoride method has a large yield and is easy for industrial production, so that Al-Ti and Al-Ti-B intermediate alloys are generally prepared by adopting the fluoride method. Zhao Kai (influence of smelting process on Al-Ti-B intermediate alloy structure [ J)]Casting technology 2020, 41(09): 816-]University of Kunming science, 2019.) on the influence of Al-Ti-B/Al-Ti master alloy on grain refinement of aluminum alloy, and the like, found that Al-Ti and Al-Ti-B master alloys pass through Al₃Ti and TiB₂The heterogeneous nucleation in the aluminum matrix improves the nucleation rate of the aluminum alloy, thereby refining the crystal grains.

In recent years, a novel Al-Ti-C intermediate alloy is developed on the basis of an Al-Ti-B refiner, and a large amount of TiC and Al are generated in a self-propagating product through the self-propagating reaction of Al powder, Ti powder and graphite powder₃Ti, and then diluting by pure aluminum to prepare the Al-Ti-C intermediate alloy. Influence of Huangyuanchun et Al (Al-Ti-C and Al-Ti-B on microstructure and mechanical properties of 7050 aluminum alloys [ J]Material engineering 2015, 43(12): 75-80.) found that Al is formed by peritectic reaction₃Ti and TiC which is in a face-centered cubic structure with alpha (Al) are high-quality nucleation substrates, and can promote heterogeneous nucleation of the alpha (Al) and refine grains.

Nevertheless, the grain refiner of aluminum alloys, which is currently mainstream, has the following major problems.

1) Zhanggujun et Al (resistance to Zr poisoning) influence of Al-Ti-B-C intermediate alloy on mechanical properties of 7050 aluminum alloy [ J]The process of material engineering, 2017,45(04) 1-8.) found that the Al-Ti and Al-Ti-B master alloys form ZrB due to the Zr/Ti reaction₂Resulting in "poisoning" of the aluminum alloy in TiB₂Will be adhered with a layer of ZrB₂，ZrB₂Has much lower nucleation capability than TiB₂Thus resulting in a reduction in the thinning effect. Furthermore, the reaction between Zr/Ti is a slow process, with the formation of a large amount of ZrB as the "poisoning" time increases₂Leading to complete failure of grain refinement and deterioration of the performance of the aluminum alloy material.

2) Through researches of albizzia (preparation of nano SiC reinforced Al-Cu composite material and tissue performance research [ D ]. university of North and Central, 2019.) and the like, TiC particles generated through self-propagating reaction are all in a micrometer scale at present, and the self-propagating temperature is high, so that the generated TiC part grows up (exceeding 20 mu m), and the refining effect is weakened. In addition, TiC belongs to ceramic particles and is easy to segregate at matrix grain boundaries, so that the overall performance of the aluminum alloy is not uniform on one hand, and excessive particles are gathered at the grain boundaries on the other hand, and the TiC is an important reason for the generation of crack sources (Huming. Al-Ti-C influences the structure and performance of ZL205A alloy [ D ]. university of Hunan, 2017.).

Disclosure of Invention

The invention aims to provide an Al-Ti-SiC intermediate alloy containing micro-nano scale TiC/SiC particles and a preparation method of the intermediate alloy.

The master alloy is used in the aluminum alloy material to improve the heterogeneous nucleation capability of the aluminum alloy material, refine the crystal grains of the aluminum alloy material and improve the comprehensive mechanical property of the aluminum alloy material, which is another purpose of the invention.

The Al-Ti-SiC intermediate alloy is prepared by mixing 40-50 wt% of Al powder, 45-55 wt% of Ti powder and 5-15 wt% of nano SiC powder, pressing and forming, performing high-temperature self-propagating combustion to obtain a self-propagating product, adding the self-propagating product into molten aluminum liquid, diluting to 5-5.3 wt% of Ti element, and pouring.

Furthermore, the invention also provides a preparation method of the suitable Al-Ti-SiC intermediate alloy.

1) Mixing the raw materials according to the proportion of 40-50 wt% of Al powder, 45-55 wt% of Ti powder and 5-15 wt% of nano SiC powder, and performing ball milling and mixing in a vacuum ball milling tank to obtain alloy powder.

2) And carrying out cold press molding on the alloy powder, and carrying out self-propagating reaction in a vacuum environment at 945-955 ℃ to obtain a self-propagating product.

3) And adding the self-propagating product into molten aluminum until the content of Ti element in the molten aluminum is 5-5.3 wt%, uniformly smelting, cooling to 708-712 ℃, and pouring to prepare an Al-Ti-SiC intermediate alloy ingot.

In the method for preparing the Al-Ti-SiC master alloy, the raw materials of the Al powder and the Ti powder are preferably powder raw materials with the grain diameter not more than 200 mu m.

Further, the particle size of the nano SiC powder is preferably not more than 40 nm.

In the preparation method of the Al-Ti-SiC intermediate alloy, the ball milling mixing is specifically (2.0-3.0) x 10^-3Pa under vacuum.

More specifically, under the vacuum condition, the raw materials are ball-milled and mixed for 5-8 h at the rotating speed of 230-250 rpm according to the ball-material ratio of 8: 1.

And after the ball milling and mixing are finished, restoring the vacuum ball milling tank to normal pressure, standing for 1-2 h, and then taking out the alloy powder uniformly mixed in the vacuum ball milling tank.

Further, the uniformly mixed alloy powder is subjected to cold press molding by a load of 15-30 kN.

The molten aluminum is obtained by completely melting a pure aluminum ingot at 940-960 ℃.

Preferably, the self-propagating product is added into the molten aluminum liquid, and in the smelting process of the aluminum liquid, the mixture is stirred for 1-2 min every 13-15 min until all the self-propagating product particles in the aluminum liquid are molten, and then the mixture is kept stand until the temperature of the aluminum liquid is 708-712 ℃, and the standing time is not less than 10 min.

And then pouring the cooled molten aluminum into an ingot casting mold preheated to 230-250 ℃ to prepare an Al-Ti-SiC intermediate alloy ingot.

The invention obtains the high-content Al by self-propagating high-temperature synthesis of Al powder, Ti powder and nano SiC powder₃And diluting the self-propagating product of Ti, TiC and a small amount of SiC particles by pure aluminum to prepare the Al-Ti-SiC intermediate alloy containing the micro-nano scale TiC/SiC particles.

The Al-Ti-SiC intermediate alloy has high product purity, and the preparation method is simple, consumes less energy and reduces the production cost.

The Al-Ti-SiC intermediate alloy can be used as a grain refiner and used for preparing various aluminum alloys.

Further, the aluminum alloy may include, but is not limited to, various cast aluminum alloys, forged aluminum alloys, or rolled aluminum alloys.

When the Al-Ti-SiC intermediate alloy is used as a grain refiner, the use method is simple, and only the intermediate alloy needs to be directly added into a refined aluminum alloy melt.

Generally, the Al-Ti-SiC master alloy is added into the aluminum alloy in a proportion of 0.3-3.0 wt%.

According to the invention, element Ti and nano SiC react through a high-temperature self-propagating reaction to generate micro-nano TiC particles with the particle size of about 0.5 mu m, and the heterogeneous nucleation effect is more obvious.

Compared with the traditional micron TiC, the micro-nano TiC particles are smaller in size, distributed in a dispersed mode, and better in particle strengthening and pinning dislocation effects.

Meanwhile, the invention adds the unreacted part of the nano SiC particles into the aluminum alloy melt by an intermediate alloy method, thereby solving the problems of poor wettability and easy agglomeration of SiC and Al-based materials. And unreacted partial nano SiC particles enter the aluminum alloy melt in a mode of intermediate alloy, so that crystal grains can be refined, and dislocation is pinned, and the effect of strengthening the aluminum alloy matrix is further achieved.

Therefore, the Al-Ti-SiC intermediate alloy of the invention contains two kinds of heterogeneous nucleation particles of TiC and SiC at the same time, and the TiC and SiC particles can strengthen the aluminum alloy matrix at the same time when being added into the aluminum alloy matrix.

The Al-Ti-SiC intermediate alloy of the invention is added into the aluminum alloy, the grain refining effect of the aluminum alloy is obvious, and the tensile strength, the elongation, the impact toughness and other mechanical properties of the aluminum alloy are improved due to the obvious refining of the aluminum alloy grains.

Drawings

FIG. 1 is a scanning electron micrograph of 10Al-9Ti-SiC, a self-propagating product prepared in example 1.

FIG. 2 is an X-ray diffraction pattern of the self-propagating product 10Al-9Ti-SiC prepared in example 1.

FIG. 3 is a SEM of Al-5Ti-0.5SiC master alloy prepared in example 1.

FIG. 4 is a scanning electron micrograph of 50Al-35Ti-15SiC, a self-propagating product prepared in example 2.

FIG. 5 is an X-ray diffraction pattern of 50Al-35Ti-15SiC, a self-propagating product prepared in example 2.

FIG. 6 is a scanning electron micrograph of the Al-5Ti-2SiC master alloy prepared in example 2.

FIG. 7 is a graph showing the effect of grain refinement of an Al-5Ti-0.5SiC master alloy on pure aluminum.

FIG. 8 is a graph showing the effect of grain refinement of Al-5Ti-2SiC master alloy on pure aluminum.

FIG. 9 is a scanning electron micrograph of as-cast grains of aluminum alloy ZL205A and modified aluminum alloy ZL 205A.

FIG. 10 is an aging scanning electron microscope map of the modified aluminum alloy ZL 205A.

FIG. 11 is a scanning electron micrograph of a fracture of aluminum alloy ZL205A and modified aluminum alloy ZL 205A.

FIG. 12 is a scanning electron micrograph of as-cast grains of aluminum alloy ZL201A and modified aluminum alloy ZL 201A.

FIG. 13 is a graph of the absorption power of a modified aluminum alloy ZL201A with various amounts of Al-5Ti-2SiC master alloy added.

Detailed Description

The following examples further describe embodiments of the present invention. The following examples are only for more clearly illustrating the technical solutions of the present invention so as to enable those skilled in the art to better understand and utilize the present invention, and do not limit the scope of the present invention. The following examples of the present invention are not intended to be exhaustive or to limit the invention to the precise forms disclosed. Various changes, modifications, substitutions and alterations to these embodiments will be apparent to those skilled in the art without departing from the principles and spirit of this invention.

In the present invention, the terms such as "upper", "lower", "left", "right" and "middle" are used for clarity of description only, and are not used to limit the scope of the present invention, and the relative relationship changes or adjustments may be made without substantial technical changes and modifications.

Example 1.

3g of SiC powder, 30g of Al powder and 27g of Ti powder are weighed in sequence and put into a vacuum ball-milling tank, grinding balls are put into the vacuum ball-milling tank according to the ball-material ratio of 8: 1, the rotating speed is set to be 250rpm, and the ball-milling and mixing are carried out for 8 hours in a vacuum state.

And opening the air valve after the ball milling is finished, standing for 2h, taking out alloy powder, putting the alloy powder into a cold pressing die, and setting the load to be 20kN for cold pressing and molding. Then placing the mixture in a vacuum molybdenum wire furnace, and synthesizing by high-temperature self-propagating combustion to obtain 58g of self-propagating product 10Al-9Ti-SiC when the furnace temperature reaches 950 ℃.

FIGS. 1 and 2 show SEM and XRD patterns of the self-propagating product 10Al-9Ti-SiC, respectively. As can be seen from the combination of FIGS. 1 and 2, Al is present in the self-propagating product₃Ti, TiC and the remaining SiC particles.

And crushing the obtained self-propagating product 10Al-9Ti-SiC by a hydraulic press at the pressure of 1 t.

Weighing 270g of pure aluminum according to the mass ratio of the Ti element in the intermediate alloy being 5%, adding the pure aluminum into a resistance furnace, smelting at 950 ℃, adding 33g of crushed self-propagating products into molten aluminum, stirring for 2min at intervals of 15min until the products are completely molten, standing for 15min until the temperature of the aluminum liquid is 710 ℃.

And pouring the molten aluminum into a metal type ingot casting mold preheated to 220 ℃, and obtaining an Al-5Ti-0.5SiC intermediate alloy ingot after pouring.

As can be seen more clearly from the SEM image of fig. 3, the size of TiC particles contained in the obtained master alloy is small and reaches the micro-nanometer level after the self-propagating reaction product is diluted, and in addition, SiC particles having a particle size of about 0.1 μm are present in the self-propagating reaction product.

Example 2.

Weighing 8g of SiC powder, 27g of Al powder and 19g of Ti powder in sequence, putting into a vacuum ball-milling tank, putting into grinding balls according to the ball-material ratio of 8: 1, setting the rotating speed to be 250rpm, and carrying out ball-milling mixing for 8 hours in a vacuum state.

And opening the air valve after the ball milling is finished, standing for 2h, taking out alloy powder, putting the alloy powder into a cold pressing die, and setting the load to be 30kN for cold pressing and molding. Then placing the mixture in a vacuum molybdenum wire furnace, and synthesizing by high-temperature self-propagating combustion to obtain 50g of self-propagating product 50Al-35Ti-15SiC when the furnace temperature reaches 950 ℃.

As can be seen by combining the SEM image of FIG. 4 and the XRD image of FIG. 5, the self-propagating product 50Al-35Ti-15SiC obtained by high-temperature self-propagating synthesis has a small amount of Al₃Ti, distributed with more TiC and the rest SiC particles.

And crushing the obtained self-propagating product 50Al-35Ti-15SiC by using a hydraulic press at the pressure of 2 t.

Weighing 240g of pure aluminum according to the mass ratio of the Ti element in the intermediate alloy being 5%, adding the pure aluminum into a resistance furnace, smelting at 950 ℃, adding 40g of crushed self-propagating product into molten aluminum, stirring for 1min at intervals of 10min until the pure aluminum is completely molten, standing for 15min until the temperature of the aluminum liquid is 710 ℃.

And pouring the molten aluminum into a metal type ingot casting mold preheated to 220 ℃, and obtaining an Al-5Ti-2SiC intermediate alloy ingot after the pouring is finished.

As can be seen from the SEM image of fig. 6, the size of TiC particles in the master alloy obtained by diluting the self-propagating product is small and reaches the micro-nanometer level, and in addition, SiC particles having a particle size of about 0.3 μm are present in the self-propagating reaction product.

Example 1 is applied.

1.5kg of aluminum ingot is taken and smelted at 700 ℃, after the aluminum ingot is completely melted, Al-5Ti-0.5SiC intermediate alloy with the mass of 0.0wt%, 0.5wt%, 1.0wt% and 3.0wt% of the aluminum ingot and Al-5Ti-2SiC intermediate alloy with the mass of 0.0wt%, 0.3wt%, 0.7wt%, 1.2wt% and 2.0wt% of the aluminum ingot are respectively added, and after the heat preservation is carried out for 10min respectively, the mixture is poured into a serpentine metal mold preheated to 250 ℃.

And cooling to room temperature, taking out an aluminum bar cast ingot, taking a metallographic sample of 15mm multiplied by 15mm from the lower end, grinding and polishing the metallographic sample, performing macroscopic corrosion, and taking a picture by using a body type microscope.

As can be seen from the gold phase diagram of FIG. 7, as the mass of the Al-5Ti-0.5SiC master alloy added into the pure aluminum is increased, the pure aluminum crystal grains are transformed from columnar crystal orientation to isometric crystal, the size of the pure aluminum crystal grains is reduced from 4500 μm (FIG. 7a) to 450 μm (FIG. 7d), the crystal grain size is thinned by 90%, and the effect is remarkable.

Similarly, as the mass of the Al-5Ti-2SiC intermediate alloy in the pure aluminum is increased in FIG. 8, the pure aluminum crystal grains are transformed from columnar crystal orientation equiaxed crystal, the size of the pure aluminum crystal grains is reduced from 4200 μm (FIG. 8a) to 325 μm (FIG. 8e), the grain size is refined by 92.2%, and the effect is remarkable.

Example 2 is applied.

The aluminum alloy ZL205A is prepared according to the following components and percentage contents.

1.5kg of aluminum alloy ZL205A is added into a smelting furnace and heated to 780 ℃ for smelting.

Standing for 10min after the aluminum alloy is completely melted, stirring with a graphite rod, cooling to 730 deg.C, adding 9g C₂Cl₆And after refining and degassing, slagging off to obtain refined aluminum liquid.

And (3) raising the temperature of the aluminum liquid to 780 ℃, adding 4.5g of Al-5Ti-0.5SiC intermediate alloy ingot prepared in the example 1, stirring for 1min, standing, naturally cooling to 710 ℃, pouring into a metal serpentine mold preheated to 250 ℃, and cooling to room temperature to obtain the modified aluminum alloy ZL205A tensile test bar.

FIG. 9 shows metallographic structure analysis of the aluminum alloy ZL205A (a) and a modified aluminum alloy ZL205A (b) with 3 wt.% Al-5Ti-0.5SiC master alloy added. After comparison, the grain size of the aluminum alloy ZL205A is 96 mu m, the grain size of the modified aluminum alloy ZL205A is 58 mu m, the grain of the modified aluminum alloy ZL205A added with the intermediate alloy is obviously refined, and the refining effect is improved by 39.5%.

The modified aluminum alloy ZL205A is subjected to solid solution at 538 ℃ for 14h, is aged for 8h, is polished and corroded by a keller reagent, and is observed under a scanning electron microscope. As shown in FIG. 10, alpha (Al) and acicular theta' (Al) of the modified aluminum alloy ZL205A containing Al-5Ti-0.5SiC master alloy were observed₂Cu) there are many bright white TiC, SiC particles near the grain boundary and theta' (Al)₂Cu) in the vicinity of the grain boundary, pinning the grain boundary and theta' (Al)₂Cu) can block the movement of dislocation and grain boundary, and the material performance is improved.

According to GB/T228.1-2010 metallic material tensile test part 1: the room temperature test method comprises the steps of carrying out tensile test on common aluminum alloy ZL205A and modified aluminum alloy ZL205A added with 3wt% of Al-5Ti-0.5SiC intermediate alloy, wherein the test results show that the material performance of the modified aluminum alloy ZL205A is obviously improved due to grain refinement and the pinning effect of TiC and SiC on grain boundaries. The specific experimental results are as follows.

The experimental results show that the tensile strength of the modified aluminum alloy ZL205A is improved by 11.4% relative to that of the aluminum alloy ZL205A on the premise that the elongation is not reduced.

Fracture scans of tensile bars of aluminum alloy ZL205A (a) and modified aluminum alloy ZL205A (b) after tensile testing were performed. As can be seen from the fracture scanning picture in FIG. 11, the modified Al alloy ZL205A with Al-5Ti-0.5SiC intermediate alloy has small and deep fracture (b) and more uniform distribution, thus having better toughness.

Example 3 is applied.

The aluminum alloy ZL201A is prepared according to the following components and percentage content thereof.

2.4kg of aluminum alloy ZL201A is added into a smelting furnace and heated to 750 ℃ for smelting.

Standing for 10min after the aluminum alloy is completely melted, stirring with a graphite rod, cooling to 730 deg.C, and adding 14g C₂Cl₆And after refining and degassing, slagging off to obtain refined aluminum liquid.

Raising the temperature of the aluminum liquid to 750 ℃ again, adding 2.4g, 4.8g, 7.2g, 9.6g and 12.0g of Al-5Ti-2SiC intermediate alloy cast ingots prepared in the example 2 respectively, stirring for 1min, standing, naturally cooling to 710 ℃, pouring into a metal Y-shaped mold preheated to 250 ℃, and cooling to room temperature to obtain series modified aluminum alloy ZL201A samples with the intermediate alloy contents of 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt% and 0.5wt%, respectively.

FIG. 12 shows metallographic structure analysis of the Al alloy ZL201A (a) without addition of master alloy and the modified Al alloy ZL201A (b) with addition of 0.5wt% Al-5Ti-2SiC master alloy. After comparison, the grain size of the aluminum alloy ZL201A without the addition of the master alloy is 128 microns, the grain size of the modified aluminum alloy ZL201A is 75 microns, alpha (Al) grains of the modified aluminum alloy ZL201A with the addition of the master alloy are obviously refined, and the refining effect is improved by 41.4%.

Grain refinement is always the main means for controlling the toughness of the material and avoiding brittle fracture, and is also the key means for improving the impact toughness of the aluminum alloy material.

According to GB/T229-.

As can be seen from the combination of FIG. 12, the impact toughness absorption power of the modified aluminum alloy ZL201A is remarkably increased along with the refinement of crystal grains, the absorption power of the modified aluminum alloy ZL201A with 0.5wt% of Al-5Ti-2SiC intermediate alloy is increased by 3 times of that of the aluminum alloy without the intermediate alloy, and the toughness is obviously improved.

Claims

1. An Al-Ti-SiC intermediate alloy is prepared by mixing 40-50 wt% of Al powder, 45-55 wt% of Ti powder and 5-15 wt% of nano SiC powder, pressing, performing high-temperature self-propagating combustion to obtain a self-propagating product, adding the self-propagating product into molten aluminum, diluting to 5-5.3 wt% of Ti element, and pouring to obtain the intermediate alloy.

2. A method of making an Al-Ti-SiC master alloy, the method comprising:

1) mixing the raw materials according to the proportion of 40-50 wt% of Al powder, 45-55 wt% of Ti powder and 5-15 wt% of nano SiC powder, and performing ball milling and mixing in a vacuum ball milling tank to obtain alloy powder;

2) cold-pressing and molding the alloy powder, and performing self-propagating reaction in a vacuum environment at the temperature of 945-955 ℃ to obtain a self-propagating product;

3. The method according to claim 2, wherein the particle diameters of the raw material powders Al and Ti are not more than 200 μm, and the particle diameter of the nano SiC powder is not more than 40 nm.

4. The method according to claim 2, wherein the ball milling mixing is at (2.0-3.0) x 10^-3And under the vacuum condition of Pa, ball-milling and mixing the raw materials for 5-8 h at the rotating speed of 230-250 rpm according to the ball-material ratio of 8: 1.

5. The method for preparing the alloy powder according to claim 2, wherein the alloy powder is cold-pressed under a load of 15-30 kN.

6. The preparation method of claim 2, wherein the molten aluminum is a melt obtained by completely melting a pure aluminum ingot at 940-960 ℃.

7. The preparation method of claim 2, characterized in that the self-propagating product is added into the molten aluminum, and stirred for 1-2 min every 13-15 min during the smelting process until the self-propagating product particles in the aluminum are completely melted, and then kept stand until the temperature of the aluminum liquid is 708-712 ℃, and the standing time is not less than 10 min.

8. The preparation method of the Al-Ti-SiC intermediate alloy ingot is characterized in that the cooled molten aluminum is poured into an ingot casting mold preheated to 230-250 ℃ to prepare the Al-Ti-SiC intermediate alloy ingot.

9. Use of the Al-Ti-SiC master alloy of claim 1 as an aluminum alloy grain refiner.

10. The use according to claim 9, wherein 0.3-3.0 wt% of Al-Ti-SiC master alloy is added to the aluminum alloy.