Al-Ti-V-C refiner for casting aluminum-silicon alloy as well as preparation method and application of Al-Ti-V-C refiner

Abstract

The invention belongs to the technical field of nonferrous alloy metallurgy and casting, and particularly relates to an Al-Ti-V-C refiner for casting an aluminum-silicon alloy and a preparation method and application of the Al-Ti-V-C refiner. Comprising the following steps: mixing pure Al powder, ball-milled nano TiC powder and ball-milled nano VC powder, and carrying out vacuum ball-milling mixing to obtain a mixture; and the mixture is subjected to hot pressing sintering, the temperature is increased to 290-310 DEG C for heat preservation, then the temperature is increased to 460-520 DEG C for heat preservation, a hot-pressed blank is obtained and formed, the hot-pressed blank is subjected to hot extrusion at 300-550 DEG C, and the Al-Ti-V-C refiner is obtained. The preparation method is simple, the raw material burning loss rate can be reduced, raw material loss caused by poor wettability of carbon powder and molten aluminum is avoided, uniform distribution of phases such as TiC and VC in the Al-Ti-V-C refiner is achieved, and the prepared Al-Ti-V-C grain refiner has a good grain refinement effect.

Description

Technical Field

[0001] The invention belongs to the technical field of nonferrous alloy metallurgy and casting, and specifically relates to an Al-Ti-VC refiner for casting aluminum silicon alloy and a preparation method and application thereof. Background Art

[0002] Cast aluminum silicon alloys are widely used in rail transportation, aerospace and other fields due to their excellent casting properties and good mechanical properties. The grain refinement of cast aluminum silicon alloys has a significant effect on improving the density and mechanical properties of the alloy. At present, the most commonly used refiner in industry is Al-Ti-B, but borides such as TiB2 in the Al-Ti-B refiner tend to aggregate and settle in the aluminum melt, which greatly reduces the refinement efficiency; at the same time, some elements, such as Si, Zr, Cr, etc., tend to "poison" it and reduce its refinement effect. Therefore, in view of the urgent need to refine cast aluminum silicon alloys, a new type of refiner for aluminum and its alloys is developed to replace the Al-Ti-B grain refiner.

[0003] Since the TiC and VC phases in the Al-Ti-VC grain refiner are not easy to aggregate and precipitate, and are "immune" to elements such as Si, Zr, and Cr that cause "poisoning" of Al-Ti-B, the Al-Ti-C grain refiner is one of the grain refiners with good industrial application prospects. In recent years, scientific and technological workers have developed preparation methods such as aluminothermic reduction method, pure metal particle method, and self-propagating method. However, there is a problem that carbon powder is not easily wetted by aluminum, which to a certain extent affects the preparation and promotion of Al-Ti-VC grain refiners. Moreover, when added in the form of carbon powder, A14C3 and Ti3AlC5 are generated under certain conditions, which greatly reduces the refining effect of the Al-Ti-VC grain refiner. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an Al-Ti-VC refiner for casting aluminum silicon alloy and its preparation method and application. The problem that carbon powder is not easily wetted by aluminum and generates A14C3 and Ti3AlC5 in the existing preparation process is solved, the raw material burning rate can be reduced, and the raw material loss caused by the poor wettability of carbon powder and aluminum liquid can be avoided, and the uniform distribution of TiC, VC and other phases in the Al-Ti-VC refiner can be achieved. The method has the advantages of simple preparation equipment, short process flow, uniform phase distribution, high preparation efficiency, etc. The prepared Al-Ti-VC grain refiner has a good grain refining effect.

[0005] The present invention solves the above technical problems through the following technical solutions.

[0006] The first object of the present invention is to provide a method for preparing an Al-Ti-VC refiner for casting aluminum-silicon alloy, comprising the following steps:

[0007] Pure Al powder, nano-TiC powder and nano-VC powder are mixed, and vacuum ball milling is performed to obtain a mixture.

[0008] The mixed material is hot pressed and sintered, first heated to 290°C-310°C and kept warm, then heated to 460°C-520°C and kept warm to obtain a hot pressed embryo, and then the hot pressed embryo is hot extruded at 300°C-550°C. After hot extrusion, uniformly dispersed TiC phase and VC phase are formed to obtain an Al-Ti-VC refiner.

[0009] Preferably, the specific method of hot pressing sintering is:

[0010] When the temperature is raised to 290°C-310°C and kept warm, the pressure is 290MPa-310MPa, and the holding time is 5min-30min; when the temperature is raised to 460°C-520°C, the pressure is 390MPa-410MPa, and the holding time is 30min-60min. After cooling to room temperature, a hot pressed embryo is obtained.

[0011] Preferably, the mass percentages of pure Al powder, nano-TiC powder and nano-VC powder are 80.00-99.60: 0.2-10: 0.2-10, which is 100 wt.% in total.

[0012] Preferably, during vacuum ball milling, the ball milling mixing time is 0.5h to 3h, the rotation speed is 100r / min to 200r / min, and the vacuum degree is 2×20 -2 Pa~8×20 -2 Pa.

[0013] Preferably, the method for preparing nano TiC powder or nano VC powder comprises the following steps:

[0014] First, TiC powder or VC powder and a ball milling medium with a diameter of 6 mm are ball milled at a mass ratio of 20:1 at a ball milling speed of 1700 r / min to 1900 r / min for 24 hours, and then the powder and a ball milling medium with a diameter of 2 mm are ball milled at a mass ratio of 20:1 at a ball milling speed of 1700 r / min to 1900 r / min for 24 hours to obtain nano TiC powder or nano VC powder.

[0015] Preferably, the particle sizes of TiC powder and VC powder before ball milling are both 50 μm to 100 μm; and the particle sizes of nano-TiC powder or nano-VC powder after ball milling are both 200 nm to 5000 nm.

[0016] Preferably, the extrusion ratio of hot extrusion is 3-15.

[0017] Preferably, before vacuum ball milling, the particle size of the Al powder is 40 μm to 200 μm; after vacuum ball milling, the mixture is dried at 150° C. for 1 h to 2 h.

[0018] The second object of the present invention is to provide an Al-Ti-VC refiner for casting aluminum-silicon alloy prepared by the above-mentioned preparation method, wherein the carbon content in the Al-Ti-VC refiner is 0.1wt.%~1.6wt.%, the titanium content is 2wt.%~10wt.%, and the vanadium content is 2wt.%~10wt.%.

[0019] The third object of the present invention is to provide the use of the above-mentioned Al-Ti-VC refiner for casting aluminum-silicon alloy in casting aluminum-silicon alloy, wherein the addition amount of the Al-Ti-VC refiner is 0.2wt.% to 0.6wt.%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention uses a hot pressing sintering method (HPS) to form a hot pressed embryo after vacuum ball milling with Al powder, TiC powder and VC powder, and then performs hot extrusion to obtain an Al-Ti-VC grain refiner rod. The TiC and VC phases in the prepared Al-Ti-VC grain refiner are nanometer-level and uniformly dispersed. In the grain refinement process, since the phases of nano-TiC, nano-VC, etc. are nanometer-level and the particles are uniformly dispersed, the TiC and VC phases serve as the nucleation core of α-Al, thereby improving the refinement efficiency of the Al-Ti-VC grain refiner. The preparation method is simple, the process flow is short, and the preparation efficiency is high. The raw material burnout rate can be reduced, and the raw material loss caused by the poor wettability of carbon powder and aluminum liquid can be avoided, so as to achieve uniform distribution of the phases of TiC, VC, etc. in the Al-Ti-VC grain refiner.

[0022] (2) The Al-Ti-VC grain refiner prepared by the present invention contains three phases, namely, Al, TiC and VC. Therefore, the method can realize the effective addition of nano-TiC and VC phases. In the grain refinement process, both TiC and VC phases can serve as the nucleation core of α-Al. However, since both TiC and VC are face-centered cubic, and the lattice constants of TiC (a=0.4327nm) and VC (a=0.4327nm) are very close to the lattice constant of α-Al (a=0.4172nm), TiC and VC can easily serve as the nucleation core of α-Al. Since the TiC and VC phases in the Al-Ti-VC grain refiner prepared by the method are nano-scale and uniformly dispersed, the TiC and VC phases provide a large number of crystal planes as α-Al nucleation positions, thereby improving the refinement efficiency of the Al-Ti-VC grain refiner. Therefore, this method can achieve the effective addition of nano-TiC and VC phases, and the prepared Al-Ti-VC grain refiner has a good grain refining effect.

[0023] (3) The carbon content of the Al-Ti-VC grain refiner prepared by the present invention is 0.1wt.% to 1.6wt.%, the titanium content is 2wt.% to 10wt.%, and the vanadium content is 2wt.% to 10wt.%. The Al-Ti-VC grain refiner contains only three phases of Al, TiC and VC. Therefore, the carbon content reflects the content of nano-TiC and nano-VC in the prepared refiner. The carbon content in the refiner is regulated by controlling the addition amount of nano-TiC and nano-VC, and then the phase ratio of the grain refiner is controlled. The prepared Al-Ti-VC grain refiner has a good grain refining effect. When 0.2wt.% of the Al-Ti-VC grain refiner is added to the Al-7Si alloy and kept warm for 2h, the refining effect does not show obvious decline, and has good industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the XRD pattern of the Al-3Ti-3V-1.46C refiner rod prepared in Example 1 of the present invention.

[0025] Figure 2 This is a scanning electron microscope image of the Al-3Ti-3V-1.46C refiner rod prepared in Example 1 of the present invention; Figure 2 (a) is the overall picture, and (b) is the distribution diagram of each element.

[0026] Figure 3 This is a macroscopic photograph of the Al-7Si alloy refined with 0.2wt.% of Al-3Ti-3V-1.46C grain refiner prepared in Example 1 of the present invention.

[0027] Figure 4This is a macroscopic photograph of the Al-7Si alloy refined with 0.2wt.% of Al-4.5Ti-4.5V-2.19C grain refiner prepared in Example 1 of the present invention.

[0028] Figure 5 This is a macroscopic photograph of the Al-7Si alloy refined with 0.2wt.% of Al-6Ti-6V-2.92C grain refiner prepared in Example 1 of the present invention.

[0029] Figure 6 This is a macroscopic photograph of the Al-7Si alloy without adding grain refiner according to the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0032] In the existing preparation of Al-Ti-VC grain refiners, the methods such as aluminothermic reduction, pure metal particle method, and self-propagating method are used. However, due to the problem that carbon powder is not easily wetted by aluminum, in the grain refinement process, when the Ti and V content is too high, the viscosity of the phases such as TiC and VC is too high, resulting in uneven distribution of the phases, which to a certain extent affects the preparation and promotion of Al-Ti-VC grain refiners. Moreover, when added in the form of carbon powder, A14C3 and Ti3AlC5 are generated under certain conditions, which greatly reduces the refining effect of the Al-Ti-VC grain refiner. Therefore, improving the wetting properties of carbon and preventing the production of A14C3 and Ti3AlC5 are one of the important research directions for preparing efficient Al-Ti-VC grain refiners.

[0033] Based on the above problems, on the one hand, the present invention provides a method for preparing an Al-Ti-VC refiner for casting aluminum-silicon alloy, comprising the following steps:

[0034] Pure Al powder, nano-TiC powder and nano-VC powder are mixed, and vacuum ball milling is performed to obtain a mixture.

[0035] The mixed material is subjected to hot pressing sintering, first heated to 290°C-310°C and kept warm, then heated to 460°C-520°C and kept warm to form a hot pressed embryo, and then the hot pressed embryo is hot extruded at 300°C-550°C. After hot extrusion, uniformly dispersed TiC phase and VC phase are formed to obtain an Al-Ti-VC refiner.

[0036] The invention uses a hot pressing sintering method (HPS) to form a hot pressed embryo after vacuum ball milling Al powder, nano TiC powder and nano VC powder are mixed, and then hot extrusion is performed to obtain an Al-Ti-VC refiner rod material. In the grain refinement process, the physical phases of nano TiC, nano VC and the like are of nano level and the particles are evenly dispersed. The TiC and VC physical phases serve as the nucleation core of alpha-Al, thereby improving the refinement efficiency of the Al-Ti-VC grain refiner. The preparation method is simple, the process flow is short, and the preparation efficiency is high. The raw material burning rate can be reduced, and the raw material loss caused by the poor wettability of carbon powder and aluminum liquid can be avoided. The uniform distribution of the physical phases of TiC, VC and the like in the Al-Ti-VC refiner is achieved, and the problem of uneven physical phase distribution due to excessive viscosity when the Ti and V contents of the Al-Ti-VC grain refiner are too high is solved.

[0037] In some embodiments, the specific method of hot pressing sintering is: the mixture is first heated to 290℃~310℃ and kept warm at a pressure of 290MPa~310MPa for 5min~30min, then heated to 460℃~520℃, the pressure is 390MPa~410MPa, the keeping time is 30min~60min, and then cooled to room temperature to obtain a hot pressed embryo.

[0038] In some embodiments, the mass percentages of pure Al powder, TiC powder and VC powder are 80.00-99.60:0.2-10:0.2-10, which is 100wt.% in total. In the present invention, Al-Ti-VC grain refiner rod is prepared by hot pressing, sintering and hot extrusion with Al powder, TiC powder and VC powder. The prepared Al-Ti-VC grain refiner contains only three phases of Al, TiC and VC, so the carbon content reflects the content of nano-TiC and nano-VC in the prepared refiner. The carbon content in the refiner is regulated by adjusting the addition amount of nano-TiC and nano-VC, thereby controlling the phase ratio of the grain refiner. The prepared Al-Ti-VC grain refiner has a good grain refining effect.

[0039] In some embodiments, the preparation method of nano TiC powder or nano VC powder comprises the following steps:

[0040] First, TiC powder or VC powder and a ball milling medium with a diameter of 6 mm are ball milled at a mass ratio of 20:1 at a ball milling speed of 1700 r / min to 1900 r / min for 24 hours, and then ball milled at a mass ratio of 20:1 with a ball milling medium with a diameter of 2 mm at a ball milling speed of 1700 r / min to 1900 r / min for 24 hours to obtain TiC powder or VC powder. The particle sizes of TiC powder and VC powder before ball milling are both 50 μm to 100 μm; the particle sizes of TiC powder or VC powder after ball milling are both 200 nm to 5000 nm.

[0041] In some embodiments, during vacuum ball milling, the ball milling time is 0.5-3h, the speed is 100r / min-200r / min, and the vacuum degree is 2×20 -2 Pa~8×20 -2 Pa. Before vacuum ball milling, the particle size of Al powder is 40 μm to 200 μm.

[0042] In the present invention, the influence of the size of nucleation particles on nucleation is mainly reflected in three aspects: nucleation rate, nucleation morphology and growth rate. The present invention first uses media with different particle sizes to ball-mill TiC powder and VC powder, with the aim of improving ball-milling efficiency and increasing the surface area to volume ratio of TiC powder and VC powder, and then mixes them with pure Al powder for vacuum ball-milling. The mixture has a higher surface area to volume ratio. The smaller the size of the nucleation particles, the easier it is to adsorb and capture more solute molecules, thereby more effectively promoting nucleation. The size of the nucleation particles affects the final nucleation morphology. The present invention forms finer particles through smaller nucleation particles. Under the same growth conditions, smaller nucleation particles may have a faster growth rate under specific growth conditions.

[0043] In some embodiments, the extrusion ratio of hot extrusion is 3 to 15. The purpose of hot extrusion is to obtain Al-Ti-VC refiner rods, to make the nano-TiC, nano-VC and other particles dispersed evenly, to have high preparation efficiency, and to reduce the raw material burning rate. If the extrusion ratio is too large, it cannot be extruded, and if the extrusion ratio is too small, the efficiency is too low.

[0044] In some embodiments, after vacuum ball milling, the mixture is dried at 150° C. for 1 h to 2 h to remove moisture.

[0045] On the other hand, the present invention provides an Al-Ti-VC refiner for casting aluminum silicon alloy, wherein the carbon content of the Al-Ti-VC refiner is 0.1wt.% to 1.6wt.%, the titanium content is 2wt.% to 10wt.%, and the vanadium content is 2wt.% to 10wt.%.

[0046] The Al-Ti-VC grain refiner prepared by the present invention contains three phases of Al, TiC and VC, so the method can realize the effective addition of nano TiC and VC phases. In the grain refinement process, both TiC and VC phases can serve as the nucleation core of α-Al. However, since both TiC and VC are face-centered cubic, and the lattice constant of TiC (a=0.4327nm), the lattice constant of VC (a=0.4327nm) and the lattice constant of α-Al (a=0.4172nm) are very close, TiC and VC are easy to serve as the nucleation core of α-Al. Since the TiC and VC phases in the Al-Ti-VC grain refiner prepared by the method are nano-level and uniformly dispersed, the TiC and VC phases provide a large number of crystal planes as α-Al nucleation positions, thereby improving the refinement efficiency of the Al-Ti-VC grain refiner. The problem of uneven phase distribution due to excessive viscosity when the Ti and V content of the Al-Ti-VC grain refiner is too high is solved. Therefore, this method can achieve the effective addition of nano-TiC and VC phases, and the prepared Al-Ti-VC grain refiner has a good grain refining effect. By adjusting the amount of nano-TiC and nano-VC added to control the carbon content in the refiner, and then controlling the phase ratio of the grain refiner, the prepared Al-Ti-VC grain refiner has a good grain refining effect. When 0.2wt.% of Al-Ti-VC grain refiner is added to Al-7Si alloy and kept warm for 2h, the refining effect still does not show obvious decline, and has good industrial application prospects.

[0047] The invention is further described below through specific examples.

[0048] Example 1

[0049] A method for preparing an Al-3Ti-3V-1.46C refiner for casting aluminum silicon alloy comprises the following steps:

[0050] S1. Put TiC powder or VC powder with a particle size of 100μm into a high-energy ball mill at a speed of 1800r / min, then add a ball mill with a diameter of 6mm to TiC powder or VC powder and agate ball milling medium at a mass ratio of 20:1, and grind the crushed material for 24h; finally, add a ball mill with a diameter of 2mm to TiC powder or VC powder and agate ball milling medium at a mass ratio of 20:1, and grind the crushed material for 24h; obtain nano TiC powder or nano VC powder with a particle size of 2000nm respectively.

[0051] S2, pure Al powder, nano-TiC powder and nano-VC powder in a mass percentage of 92.55wt.%: 3.75wt.%: 3.70wt.%, totaling 100wt.%, ball milled for 2h, with a rotation speed of 150r / min and a vacuum degree of 5×20 -2Pa, a fully mixed mixture of pure Al powder, nano-TiC powder and nano-VC powder is obtained.

[0052] S3. Weigh a mixture of pure Al powder, nano-TiC powder and nano-VC powder, heat it to 150°C and dry it for 1 hour to remove moisture.

[0053] S4. Put the dried mixed material into a FHP-828 rapid hot pressing sintering furnace, heat to 300°C, pressure 300MPa, time 20min; heat to 490°C, pressure 400MPa, time 40min; hot press sinter the mixed material and cool to room temperature in the furnace to form a hot pressed embryo with a diameter of 60mm and a height of 50mm.

[0054] S5. The Al-Ti-VC hot pressed billet is hot extruded at 500° C. with an extrusion ratio of 5. After the extruded material is cooled to room temperature, an Al-3Ti-3V-1.46C refiner rod with a diameter of 8.5 mm is obtained.

[0055] Example 2

[0056] A method for preparing an Al-4.5Ti-4.5V-2.19C refiner for casting aluminum silicon alloy comprises the following steps:

[0057] S1. Put TiC powder or VC powder with a particle size of 100μm into a high-energy ball mill at a speed of 1800r / min, then add a ball mill with a diameter of 6mm to TiC powder or VC powder and agate ball milling medium at a mass ratio of 20:1, and grind the crushed material for 24h; finally, add a ball mill with a diameter of 2mm to TiC powder or VC powder and agate ball milling medium at a mass ratio of 20:1, and grind the crushed material for 24h; obtain nano TiC powder or nano VC powder with a particle size of 2000nm respectively.

[0058] S2, pure Al powder, nano-TiC powder and nano-VC powder in a mass percentage of 88.82wt.%: 5.63wt.%: 5.55wt.%, totaling 100wt.%, ball milled for 2h, with a rotation speed of 150r / min and a vacuum degree of 5×20 -2 Pa, a fully mixed mixture of pure Al powder, nano-TiC powder and nano-VC powder is obtained.

[0059] S3. Weigh a mixture of pure Al powder, nano-TiC powder and nano-VC powder, heat it to 150°C and dry it for 1 hour to remove moisture.

[0060] S4. Put the dried mixed material into a FHP-828 rapid hot pressing sintering furnace, heat to 300°C, pressure 300MPa, time 20min; heat to 480°C, pressure 400MPa, time 30min; hot press sinter the mixed material and cool to room temperature in the furnace to form a hot pressed embryo with a diameter of 40mm and a height of 20mm.

[0061] S5. The Al-Ti-VC hot pressed billet is hot extruded at 500° C. with an extrusion ratio of 5. After the extruded material is cooled to room temperature, an Al-3Ti-3V-1.46C refiner rod with a diameter of 8.5 mm is obtained.

[0062] Example 3

[0063] A method for preparing an Al-6Ti-6V-2.92C refiner for casting aluminum silicon alloy comprises the following steps:

[0064] S1. Put TiC powder or VC powder with a particle size of 100μm into a high-energy ball mill at a speed of 1800r / min, then add a ball mill with a diameter of 6mm to TiC powder or VC powder and agate ball milling medium at a mass ratio of 20:1, and grind the crushed material for 24h; finally, add a ball mill with a diameter of 2mm to TiC powder or VC powder and agate ball milling medium at a mass ratio of 20:1, and grind the crushed material for 24h; obtain nano TiC powder or nano VC powder with a particle size of 2000nm respectively.

[0065] S2, pure Al powder, nano-TiC powder and nano-VC powder in a mass percentage of 85.10wt.%:7.50wt.%:7.40wt.%, totaling 100wt.%, ball milled for 2h, with a rotation speed of 150r / min and a vacuum degree of 5×20 -2 Pa, a fully mixed mixture of pure Al powder, nano-TiC powder and nano-VC powder is obtained.

[0066] S3. Weigh a mixture of pure Al powder, nano-TiC powder and nano-VC powder, heat it to 150°C and dry it for 1 hour to remove moisture.

[0067] S4. Put the dried mixed material into a FHP-828 rapid hot pressing sintering furnace, heat to 300°C, pressure 300MPa, time 20min; heat to 480°C, pressure 400MPa, time 30min; hot press sinter the mixed material and cool to room temperature in the furnace to form a hot pressed embryo with a diameter of 40mm and a height of 20mm.

[0068] S5. The Al-Ti-VC hot pressed billet is hot extruded at 500° C. with an extrusion ratio of 5. After the extruded material is cooled to room temperature, an Al-3Ti-3V-1.46C refiner rod with a diameter of 8.5 mm is obtained.

[0069] The morphology and structure of the Al-2Ti-2V-0.4C refiner prepared in Example 1 were tested, and the results were as follows:

[0070] Figure 1 This is the XRD pattern of the Al-3Ti-3V-1.46C refiner rod prepared in Example 1 of the present invention. Figure 1 As shown, the prepared Al-3Ti-3V-1.46C grain refiner contains three phases of Al, TiC and VC, so this method can achieve the effective addition of nano TiC and VC phases. In the grain refinement process, TiC and VC phases can both serve as the nucleation core of α-Al, but since TiC and VC are both face-centered cubic, and the lattice constant of TiC (a=0.4327nm), the lattice constant of VC (a=0.4327nm) is very close to the lattice constant of α-Al (a=0.4172nm), TiC and VC are easy to serve as the nucleation core of α-Al. Since the TiC and VC phases in the Al-Ti-VC grain refiner prepared by this method are nano-level and uniformly dispersed, the TiC and VC phases provide a large number of crystal planes as α-Al nucleation positions, improving the refinement efficiency of the Al-Ti-VC grain refiner.

[0071] Figure 2 This is a scanning electron microscope image of the Al-3Ti-3V-1.46C refiner rod prepared in Example 1 of the present invention. Figure 2 (a) is the overall picture, and (b) is the distribution diagram of each element. Figure 2 As shown, the nano-TiC and nano-VC phases are fully mixed and dispersed.

[0072] The refiner rods prepared in Examples 1 to 3 are used to cast aluminum silicon alloy, where the aluminum silicon alloy is Al-7Si alloy, and the steps specifically include:

[0073] The refiner rods prepared in Examples 1 to 3 are used to cast aluminum silicon alloy, where the aluminum silicon alloy is Al-7Si alloy, and the steps specifically include:

[0074] Step 1: put pure aluminum into a crucible and heat it to 750° C. until the Al-7Si alloy melts to form a melt.

[0075] Step 2, respectively add 0.2wt.% of the Al-3Ti-3V-1.46C refiner rod prepared in Example 1, 0.2wt.% of the Al-4.5Ti-4.5V-2.19C refiner rod prepared in Example 2, and 0.2wt.% of the Al-6Ti-6V-2.92C refiner rod prepared in Example 3 into 1000g of Al-7Si alloy melt, stir thoroughly until the grain refiner melts, and mix all the materials evenly to form a uniform mixed melt.

[0076] Step 3: Keep the mixed melt at 750°C for 15 minutes, stir it every 3 minutes for 2 minutes, and then pour it into a steel mold to form an ingot; the ingot is polished and corroded to observe the grains. Figure 3-5 shown.

[0077] The Al-7Si alloy melt without grain refiner was used as a comparative example. After stirring, it was kept warm for 10 minutes, poured, corroded, and its grain size was measured. Figure 6 shown.

[0078] Figure 3 This is a macroscopic photograph of the Al-7Si alloy refined by 0.2wt.% of Al-3Ti-3V-1.46C grain refiner prepared in Example 1 of the present invention. Figure 3 As shown, the average grain size of the aluminum-silicon alloy can be refined from 1463±10μm to 320±50μm.

[0079] Figure 4 This is a macroscopic photograph of the Al-7Si alloy refined by 0.2wt.% of Al-4.5Ti-4.5V-2.19C grain refiner prepared in Example 2 of the present invention. Figure 4 As shown, the average grain size of the aluminum-silicon alloy can be refined from 1463±10μm to 291±50μm.

[0080] Figure 5 This is a macroscopic photograph of the Al-7Si alloy refined by 0.2wt.% of Al-6Ti-6V-2.92C grain refiner prepared in Example 3 of the present invention. Figure 5 As shown, the average grain size of the aluminum-silicon alloy can be refined from 1463±10μm to 297±50μm.

[0081] Figure 6 This is a macroscopic photograph of the Al-7Si alloy without adding a grain refiner. The aluminum grains without adding a grain refiner are not refined and have large sizes.

[0082] However, when using the traditional fluoride salt method to prepare a high-content refiner, such as one with more than 6Ti or 5V, it cannot be cast due to its high viscosity.

[0083] In summary, the Al-Ti-VC grain refiner prepared by the present invention contains Al, TiAl3, VA l3 , TiC and VC, five phases, so this method can achieve the effective addition of nano-TiC and VC phases, the carbon content of the prepared Al-Ti-VC grain refiner is 0.1wt.%~1.6wt.%, the titanium content is 2wt.%~10wt.%, and the vanadium content is 2wt.%~10wt.%. The content of nano-TiC in the refiner is regulated by regulating the carbon content. The prepared Al-Ti-VC grain refiner has a good grain refining effect. When 0.2wt.% of Al-Ti-VC grain refiner is added to pure aluminum and kept warm for 2h, the refining effect still does not show obvious decline.

[0084] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0085] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing an Al-Ti-VC refiner for casting aluminum silicon alloy, characterized in that: The following steps are involved: Pure Al powder, nano-TiC powder and nano-VC powder are mixed and vacuum ball milled to obtain a mixture; The mixed material is hot pressed and sintered, first heated to 290°C-310°C and kept warm, then heated to 460°C-520°C and kept warm to obtain a hot pressed embryo, and finally the hot pressed embryo is hot extruded at 300°C-550°C. After hot extrusion, uniformly dispersed TiC phase and VC phase are formed to obtain an Al-Ti-VC refiner.

2. The method for preparing the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 1, characterized in that: The specific method of hot pressing sintering is: When the temperature is raised to 290°C-310°C and kept warm, the pressure is 290MPa-310MPa, and the holding time is 5min-30min; when the temperature is raised to 460°C-520°C, the pressure is 390MPa-410MPa, and the holding time is 30min-60min. After cooling to room temperature, a hot pressed embryo is obtained.

3. The method for preparing the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 1, characterized in that: The mass percentages of pure Al powder, nano-TiC powder and nano-VC powder are 80.00-99.60: 0.2-10: 0.2-10, which is 100wt.% in total.

4. The method for preparing the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 1, characterized in that: During vacuum ball milling, the mixing time is 0.5h to 3h, the speed is 100r / min to 200r / min, and the vacuum degree is 2×20 -2 Pa~8×20 -2 Pa.

5. The method for preparing the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 1, characterized in that: The preparation method of nano TiC powder or nano VC powder comprises the following steps: First, TiC powder or VC powder and a ball milling medium with a diameter of 6 mm are ball milled at a mass ratio of 20:1 at a ball milling speed of 1700 r / min to 1900 r / min for 24 hours, and then the powder and a ball milling medium with a diameter of 2 mm are ball milled at a mass ratio of 20:1 at a ball milling speed of 1700 r / min to 1900 r / min for 24 hours to obtain nano TiC powder or nano VC powder.

6. The method for preparing the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 5, characterized in that: The particle sizes of TiC powder and VC powder before ball milling are both 50 μm to 100 μm; the particle sizes of nano-TiC powder or nano-VC powder after ball milling are both 200 nm to 5000 nm.

7. The method for preparing the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 1, characterized in that: The extrusion ratio of hot extrusion is 3-15.

8. The method for preparing the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 1, characterized in that: Before vacuum ball milling, the particle size of Al powder is 40 μm to 200 μm; after vacuum ball milling, the mixture is dried at 150° C. for 1 h to 2 h.

9. An Al-Ti-VC refiner for cast aluminum-silicon alloy prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The carbon content in the Al-Ti-VC refiner is 0.1wt.% to 1.6wt.%, the titanium content is 2wt.% to 10wt.%, and the vanadium content is 2wt.% to 10wt.%.

10. Use of the Al-Ti-VC refiner for casting aluminum-silicon alloy according to claim 9 in casting aluminum-silicon alloy, characterized in that: The added amount of the Al-Ti-VC refiner is 0.2wt.% to 0.6wt.%.

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