Aluminum-based multi-component boride grain refiner for resisting Si poisoning and its preparation method

Abstract

This invention belongs to the field of aluminum alloy grain refiners, specifically relating to an aluminum-based multi-component boride grain refiner resistant to Si poisoning and its preparation method. The grain refiner is produced by combining an aluminum matrix with hexagonal plate-like (Ti) compounds uniformly distributed within the aluminum matrix. 0.33 Nb 0.33 V 0.33 The method comprises the following steps: (1) Weighing raw materials: Weigh industrial pure aluminum, aluminum-boron master alloy, titanium, niobium, vanadium, and boron in proportion; (2) Smelting: Place industrial pure aluminum, aluminum-boron master alloy, titanium, niobium, vanadium, and boron in a water-cooled copper crucible of a vacuum arc furnace and smelt to obtain a grain refiner. The grain refiner prepared by this invention can achieve a good grain refinement effect, is inexpensive and has high preparation efficiency, and the raw materials for the grain refiner are easy to obtain.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy grain refiners, specifically relating to an aluminum-based multi-component boride grain refiner resistant to Si poisoning and its preparation method. Background Technology

[0002] Aluminum is the most abundant metal in the Earth's crust, being the most naturally occurring metallic element. Common alloying elements in aluminum alloys include silicon, iron, copper, manganese, magnesium, chromium, nickel, zinc, titanium, and zirconium. These elements improve the performance and processing characteristics of aluminum alloys, giving them advantages such as good toughness, low density, high strength, good plasticity, excellent electrical conductivity, and corrosion resistance. Because of its abundant content and excellent properties, aluminum alloys are among the first-choice lightweight metal materials in many fields, including aerospace, military, transportation, photovoltaics, machinery, medical, environmental protection, and home electronics. Advances in other new material technologies and applications in these fields demand improvements in aluminum alloy performance. Grain refinement in aluminum alloys can simultaneously improve strength and toughness, making it one of the effective methods to enhance the overall mechanical properties of aluminum alloys.

[0003] Compared to traditional Al-Ti-B grain refiners, the presence of a small amount of Si in aluminum alloys is beneficial for promoting grain refinement. However, when the Si content reaches 4% to 16%, α-Al grains often form coarse dendrites, weakening the grain refiner's ability and resulting in poor strength and plasticity of the aluminum alloy. Si "poisoning" refers to the loss of the grain refiner's nucleation function. Two widely accepted mechanisms of Si poisoning are: one is the formation of Si compounds on the surface of TiB2, causing TiB2 to lose its nucleation function; the other is that Si compounds consume solute Ti, reducing the growth factor and leading to coarse grains. The discovery of stable diborides is a breakthrough in the research of novel Si-resistant grain refiners for aluminum alloys.

[0004] Research on novel grain refiners to combat Si poisoning in aluminum alloys mainly focuses on Al-Nb-B, Al-VB, and Al-Ti-Nb-B. Among these, Al-Nb-B, due to the high density of NbB2, tends to sink in molten aluminum, forming an inhomogeneous microstructure. In Al-VB, the density of the VB2 phase is lower than that of the NbB2 phase, theoretically giving VB2 better resistance to degradation than NbB2. Compared to Al-Nb-B, Al-Ti-Nb-B, containing Ti, produces Al-Si grains with smaller sizes. However, these grain refiners do not completely solve the Si poisoning problem; therefore, the search for novel heterogeneous nucleation phases is essential.

[0005] Patent document CN114807871A, "Preparation Method and Application of a Grain Refining Agent for Silicon Poisoning-Resistant Aluminum Alloys," discloses a method for preparing nanoscale AlTiCB coatings using vacuum deposition technology. This technology utilizes an arc discharge generated between the cathode target and the coating chamber shell to excite the metal evaporation and ionization of the target (Al, Ti), which then reacts chemically with ionized gaseous ions (C, B), subsequently depositing a surface coating (AlTiBC) on the substrate. However, this technology is not suitable for industrial production. Patent document CN116356175A, "An Al-Sc-Ti Grain Refining Agent Resistant to Silicon Poisoning and Its Application," discloses an Al-Sc-Ti grain refining agent that forms a new heterogeneous nucleation phase (Al,Si)3(Ti,Sc), resulting in significant refinement of the α-Al grains in aluminum-silicon alloys. However, Sc is expensive and not suitable for large-scale production. Summary of the Invention

[0006] The purpose of this invention is to provide an aluminum-based multi-component boride grain refiner resistant to Si poisoning and its preparation method.

[0007] The technical solution to achieve the objective of this invention is: a method for preparing an aluminum-based multi-component boride grain refiner resistant to Si poisoning, comprising the following steps:

[0008] Step (1): Weigh the raw materials: Weigh industrial pure aluminum, aluminum-boron master alloy, titanium, niobium, vanadium and boron in proportion;

[0009] Step (2): Smelting: Industrial pure aluminum, aluminum-boron master alloy, titanium, niobium, vanadium and boron elements are placed in a water-cooled copper crucible of a vacuum electric arc furnace and smelted to obtain a grain refiner.

[0010] Furthermore, the specific raw material ratio in step (1) is as follows:

[0011] The molar ratio of elements Ti, Nb, V, and B satisfies Ti:Nb:V:B = 1:1:1:6, and the ratio of elements Ti, Nb, V, and B satisfies the formation of (Ti 0.33 Nb 0.33 V 0.33 B2, with boron content ranging from 1% to 2% of the total mass.

[0012] Furthermore, in step (1), the raw materials are ground and ultrasonically cleaned before being weighed.

[0013] Furthermore, step (2) includes the following steps:

[0014] Step (21): Place the raw material weighed in step (1) into a water-cooled copper crucible of a vacuum arc furnace; place the pure Ti particles after removing the residual oxygen into another water-cooled copper crucible;

[0015] Step (22): Evacuate the electric arc furnace until the vacuum level is greater than 5×10⁻⁶. -3 At Pa, argon protective gas is introduced until the furnace pressure is negative 0.05 Pa; the DC power switch for melting is turned on, and pure Ti particles are melted first to absorb the remaining oxygen in the furnace cavity; then the raw materials are melted until the reaction is complete, and after cooling and solidification, aluminum alloy ingots are obtained.

[0016] Step (23): Repeat the melting and flipping of the aluminum alloy ingot 3 to 5 times to obtain an aluminum alloy ingot with a uniform structure.

[0017] Furthermore, step (22) "then melt the raw materials until the reaction is complete" specifically means: first melt for 1 min to 3 min under a current of 50 to 250 A, and then melt for 1 min to 3 min under a current of 250 A to 500 A.

[0018] A silicon-poisoning-resistant aluminum-based multi-component boride grain refiner, prepared by the above method, consists of an aluminum matrix and hexagonal plate-like (Ti) compounds uniformly distributed within the aluminum matrix. 0.33 Nb 0.33 V 0.33 Composed of B2 particles, (Ti 0.33 Nb 0.33 V 0.33 The particle size of B2 particles is 1–3 μm.

[0019] A method for refining aluminum-silicon alloys using the aforementioned refining agent includes the following steps:

[0020] Step S1: Ingredients: Weigh out aluminum-silicon alloy ingots and the above-mentioned aluminum-based multi-component boride grain refiner that resists Si poisoning according to the proportion;

[0021] Step S2: Smelting:

[0022] Step S21: Place the aluminum-silicon alloy ingot weighed in step S1 into a graphite clay crucible, and place it together with the crucible into a pit-type resistance furnace. Heat and maintain the temperature of the pit-type resistance furnace until the aluminum ingot is completely melted, and stir with a graphite rod.

[0023] Step S22: Wrap the refining agent weighed in step S1 in aluminum foil and add it to the molten metal in step S21. Stir and keep warm with a graphite rod to obtain a molten metal containing the refining agent.

[0024] Step S23: Solidification: The molten metal containing the refining agent obtained in step S22 is poured into a preheated metal mold and allowed to cool and solidify to obtain the refined aluminum alloy ingot.

[0025] Furthermore, in step S1, the mass fraction of the aluminum-silicon alloy ingot weighed is 99% to 99.9%, and the mass fraction of the refining agent weighed is 0.1% to 1%.

[0026] Furthermore, the step S21 of "heating and holding the well-type resistance furnace" specifically refers to: heating the well-type resistance furnace to 720℃~750℃ and holding it for 1h~2h.

[0027] The "stirring with a graphite rod and keeping warm" in step S22 specifically means: stirring with a graphite rod for 30s to 60s and keeping warm for 10min to 60min.

[0028] An aluminum-silicon alloy is prepared using the method described above.

[0029] Compared with the prior art, the significant advantages of this invention are:

[0030] The Ti, Nb, V, and B elements added in this invention can form heterogeneous particles. The lattice constants of these heterogeneous particles can be well matched with the lattice constants of aluminum alloys. In the metal solution, Ti, Nb, V, and B atoms will combine with each other or with Al atoms to form TiAl3, TiB2, NbB2, and VB2 as heterogeneous nucleation phases of α-Al, which can play the role of heterogeneous nucleation cores and achieve a significant grain refinement effect.

[0031] The elements of the present invention simultaneously form a core-shell structure, with a central layer of (NbTiV)B2 and an outer layer of (TiV)B2. No Si enrichment was found on the

[011] surface, which plays a certain role in resisting Si "poisoning".

[0032] The refining agent prepared using this invention can achieve a good refining effect, is inexpensive, has high preparation efficiency, and the raw materials for the refining agent are readily available. Attached Figure Description

[0033] Figure 1 SEM image of the anti-Si "poisoning" multi-component boride aluminum-based grain refiner prepared in Example 1.

[0034] Figure 2 The image shows the SEM image of the anti-Si "poisoning" multi-component boride aluminum-based grain refiner prepared in Example 2.

[0035] Figure 3 Macroscopic image of aluminum-silicon alloy without added refining agent.

[0036] Figure 4 0.1 wt% Al to Ti was added to Example 3 0.33 Nb 0.33 V 0.33 Macroscopic microstructure of aluminum-silicon alloy with B2 refining agent.

[0037] Figure 5 0.2 wt% Al-(Ti) was added to Example 4 0.33 Nb 0.33 V 0.33 Macroscopic microstructure of aluminum-silicon alloy with B2 refining agent.

[0038] Figure 6 0.5 wt% Al~(Ti) was added to Example 5 0.33 Nb 0.33 V 0.33 Macroscopic microstructure of aluminum-silicon alloy with B2 refining agent.

[0039] Figure 7 Add 1 wt% Al to (Ti) in Example 6 0.33 Nb 0.33 V 0.33 Macroscopic microstructure of aluminum-silicon alloy with B2 refining agent. Detailed Implementation

[0040] The present invention will now be described in further detail with reference to the accompanying drawings.

[0041] Example 1

[0042] A method for preparing a multi-component boride grain refiner resistant to Si poisoning.

[0043] Step (1): Weigh the raw materials: Weigh 8.33 grams of Al-3B master alloy, 0.18 grams of Ti elemental, 0.35 grams of Nb elemental, 0.19 grams of V elemental and 1 gram of B elemental.

[0044] Step (2) Smelting: Industrial pure aluminum, titanium, niobium, vanadium, and boron are placed in a water-cooled copper crucible of a vacuum electric arc furnace and smelted to obtain the grain refiner Al-3.9(Ti 0.33 Nb 0.33 V 0.33 B2. The prepared refining agent, such as... Figure 1 As shown.

[0045] Example 2

[0046] A method for preparing a multi-component boride grain refiner resistant to Si poisoning.

[0047] Step (1): Weigh the raw materials: Weigh 16.66 grams of Al-3B master alloy, 0.37 grams of Ti elemental, 0.70 grams of Nb elemental, 0.38 grams of V elemental and 2 grams of B elemental.

[0048] Step (2) Smelting: Industrial pure aluminum, titanium, niobium, vanadium, and boron are placed in a water-cooled copper crucible of a vacuum electric arc furnace and smelted to obtain grain refiner Al-7.8 (Ti 0.33 Nb 0.33V 0.33 B2. The prepared refining agent, such as... Figure 2 As shown.

[0049] Example 3

[0050] A method for applying a multi-component boride grain refiner that resists Si “poisoning” includes the following steps.

[0051] Ingredients: Weigh out 99.9% aluminum-silicon alloy ingots and 0.1% (by mass) Al-3.9(Ti) multi-component boride grain refiner to resist Si poisoning. 0.33 Nb 0.33 V 0.33 B2; Place the weighed aluminum-silicon alloy ingot into a graphite clay crucible, and place the crucible together in a pit-type resistance furnace. Heat the pit-type resistance furnace to 720℃~750℃ and hold for 1h~2h until the aluminum ingot is completely melted. Wrap the weighed refining agent in aluminum foil and add it to the molten metal. Stir with a graphite rod for 30s~60s and hold for 10min~60min to obtain a molten metal containing the refining agent. Finally, pour the molten metal containing the refining agent into a preheated metal mold according to different holding times. After cooling and solidification, the refined aluminum alloy ingot is obtained.

[0052] Example 4

[0053] A method for applying a multi-component boride grain refiner that resists Si “poisoning” includes the following steps.

[0054] Ingredients: Weigh out 99.8% aluminum-silicon alloy ingots and 0.2% (by mass) Al-3.9(Ti) multi-component boride grain refiner to resist Si poisoning. 0.33 Nb 0.33 V 0.33 B2; Place the weighed aluminum-silicon alloy ingot into a graphite clay crucible, and place the crucible together in a pit-type resistance furnace. Heat the pit-type resistance furnace to 720℃~750℃ and hold for 1h~2h until the aluminum ingot is completely melted. Wrap the weighed refining agent in aluminum foil and add it to the molten metal. Stir with a graphite rod for 30s~60s and hold for 10min~60min to obtain a molten metal containing the refining agent. Finally, pour the molten metal containing the refining agent into a preheated metal mold according to different holding times. After cooling and solidification, the refined aluminum alloy ingot is obtained.

[0055] Example 5

[0056] A method for applying a multi-component boride grain refiner that resists Si “poisoning” includes the following steps.

[0057] Ingredients: Weigh out 99.5% aluminum-silicon alloy ingots and 0.5% (by mass) Al-3.9 (Ti) multi-component boride grain refiner to resist Si poisoning. 0.33 Nb 0.33 V 0.33 B2; Place the weighed aluminum-silicon alloy ingot into a graphite clay crucible, and place the crucible together in a pit-type resistance furnace. Heat the pit-type resistance furnace to 720℃~750℃ and hold for 1h~2h until the aluminum ingot is completely melted. Wrap the weighed refining agent in aluminum foil and add it to the molten metal. Stir with a graphite rod for 30s~60s and hold for 10min~60min to obtain a molten metal containing the refining agent. Finally, pour the molten metal containing the refining agent into a preheated metal mold according to different holding times. After cooling and solidification, the refined aluminum alloy ingot is obtained.

[0058] Example 6

[0059] A method for applying a multi-component boride grain refiner that resists Si “poisoning” includes the following steps.

[0060] Ingredients: Weigh out 99% aluminum-silicon alloy ingots and 1% (by mass) Al-3.9(Ti) multi-component boride grain refiner to resist Si poisoning. 0.33 Nb 0.33 V 0.33 B2 1%; Place the weighed aluminum-silicon alloy ingot into a graphite clay crucible, and place the crucible together in a pit-type resistance furnace. Heat the pit-type resistance furnace to 720℃~750℃ and hold for 1h~2h until the aluminum ingot is completely melted; Wrap the weighed refining agent in aluminum foil and add it to the molten metal, and stir with a graphite rod for 30s~60s and hold for 10min~60min to obtain a molten metal containing the refining agent; Finally, pour the obtained molten metal containing the refining agent into a preheated metal mold according to different holding times, and wait for it to cool and solidify to obtain the refined aluminum alloy ingot.

[0061] Figure 1 and Figure 2 These are SEM images of the prepared refining agent, from... Figure 1-2 It can be found that (Ti) 0.33 Nb 0.33 V 0.33 B2 particles are hexagonal plates with a large surface area, which provides more nucleation sites and is beneficial for grain refinement.

[0062] Figures 3 to 7 This is a schematic diagram of the macrostructure of the surface of an aluminum-silicon ingot after etching. Observation clearly shows a reduction in grain size. Further statistical analysis of grain size revealed that a grain size of 173.26 μm was achieved with a 1% addition of a grain refiner. (See [link to relevant documentation]). Figure 7 .

Claims

1. A method for preparing an aluminum-based multinary boride grain refiner resistant to Si poisoning, characterized in that, It comprises the following steps: Step (1): weighing raw materials: weighing industrial pure aluminum, aluminum-boron intermediate alloy, titanium element, niobium element, vanadium element, boron element according to the proportion; the raw material ratio in step (1) is specifically: The molar ratio of Ti, Nb, V and B satisfies Ti:Nb:V:B=1:1:1:6, and the ratio of Ti, Nb, V and B satisfies generating (Ti 0.33 Nb 0.33 V 0.33 )B2, and the mass fraction of boron accounts for 1% to 2% of the total mass fraction of the aluminum-based multicomponent boride grain refiner. Step (2): smelting: putting industrial pure aluminum, aluminum-boron intermediate alloy, titanium element, niobium element, vanadium element and boron element into a water-cooled copper crucible of a vacuum arc furnace, smelting to obtain a grain refiner, the grain refiner is composed of an aluminum matrix and (Ti 0.33 Nb 0.33 V 0.33 )B2 particles uniformly distributed in the aluminum matrix in the form of hexagonal platelets, the particle size of the (Ti 0.33 Nb 0.33 V 0.33 )B2 particles is 1-3 μm.

2. The method of claim 1, wherein, The raw materials in step (1) are polished and ultrasonically cleaned before weighing.

3. The method of claim 2, wherein, Step (2) comprises the following steps: Step (21): placing the raw materials weighed in step (1) into a water-cooled copper crucible of a vacuum arc furnace; placing pure Ti particles with removed residual oxygen into another water-cooled copper crucible; Step (22): vacuumize the arc furnace until the pressure in the furnace is lower than 5 x 10 -3 Pa, then introduce argon protection gas to make the pressure in the furnace 0.05 Pa lower than the atmospheric pressure; turn on the smelting direct current power switch, first smelt the residual oxygen in the pure Ti particle absorption furnace cavity; then smelt the raw material until complete reaction, and obtain an aluminum alloy ingot after cooling and solidification; Step (23): repeatedly turning and melting the aluminum alloy ingot for 3-5 times to obtain an aluminum alloy ingot with uniform structure.

4. The method of claim 3, wherein, The "then melting the raw materials to complete reaction" in step (22) is specifically: first melting for 1-3 min under the condition of 50-250 A current, and then melting for 1-3 min under the condition of 250 A-500 A current.

5. An aluminum-based multiboride grain refiner resistant to Si poisoning, characterized in that, Prepared by the method of any one of claims 1-4.

6. A method of refining an aluminium-silicon alloy with the refining agent of claim 5, characterised in that, It comprises the following steps: Step S1: batching: weighing aluminum-silicon alloy ingot and the Si-poisoning-resistant aluminum-based multinary boride grain refiner of claim 5 according to the proportion; Step S2: melting: Step S21: placing the aluminum-silicon alloy ingot weighed in step S1 into a graphite clay crucible, and placing the graphite clay crucible together with the crucible in an electric resistance furnace, heating and keeping the electric resistance furnace until the aluminum ingot is completely melted, and stirring with a graphite rod; Step S22: wrapping the refiner weighed in step S1 with aluminum foil and adding it into the metal liquid in step S21, and stirring and keeping with a graphite rod to obtain a metal liquid containing the refiner; Step S23: solidification: pouring the metal liquid containing the refiner obtained in step S22 into a preheated metal mold, and cooling and solidifying to obtain a refined aluminum alloy ingot.

7. The method of claim 6, wherein, The mass fraction of the aluminum-silicon alloy ingot weighed in step S1 is 99%-99.9%, and the mass fraction of the refiner weighed is 0.1%-1%.

8. The method of claim 7, wherein, The "heating and keeping the electric resistance furnace" in step S21 is specifically: heating the electric resistance furnace to 720-750 ℃ and keeping for 1-2 h; The "stirring and keeping with a graphite rod" in step S22 is specifically: stirring with a graphite rod for 30-60 s and keeping for 10-60 min.

9. An aluminium silicon alloy, characterised in that Prepared by the method of any one of claims 6-8.

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