An Al-Sc-Ti grain refiner capable of resisting silicon poisoning and its application

Abstract

The present invention proposes an Al-Sc-Ti grain refiner capable of resisting silicon poisoning and an application thereof, belonging to the technical field of casting; the chemical composition and mass percentage of the grain refiner are Sc: 10-50wt.%; Ti: 3-10wt.%; and the balance is Al; the Al-Sc-Ti grain refiner is used for grain refinement of aluminum-silicon alloys; after the Al-Sc-Ti grain refiner is introduced into the aluminum-silicon alloy, a heterogeneous nucleation phase (Al, Si)3(Ti, Sc) is formed in the solution and serves as a nucleation site for α-Al. The generation of the heterogeneous nucleation phase (Al, Si)3(Ti, Sc) greatly refines the α-Al grains in the aluminum-silicon alloy, greatly improving the efficiency of the grain refiner; the heterogeneous nucleation phase (Al, Si)3(Ti, Sc) is not affected by Si in the aluminum-silicon alloy, thereby avoiding the influence of silicon poisoning in the aluminum-silicon alloy.

Description

Technical Field

[0001] The invention belongs to the technical field of casting, and in particular relates to an Al-Sc-Ti grain refiner capable of resisting silicon poisoning and application thereof. Background Art

[0002] Al-Si casting alloys, such as A356 and A357, are widely used in the automotive manufacturing field due to their low thermal expansion coefficient, high wear resistance and low cost. Grain refinement is one of the important methods to improve the performance of Al-Si alloys. Grain refiners not only redistribute the porosity of the casting, but also reduce the porosity of the casting. Generally, the selection of grain refiners should meet the two requirements of promoting nucleation and hindering grain growth. Al-Ti-B master alloys have been widely used as grain refiners in aluminum alloys because Al3Ti and TiB2 can act as heterogeneous nucleation sites for α-Al, and during solidification, excess Ti atoms can dissolve in the solid-liquid interface to limit grain growth.

[0003] Ti-containing grain refiners are perfectly suitable for aluminum alloys other than aluminum-silicon alloys. This is because the Ti, B, and C atoms in the grain refiner will combine with each other or with Al atoms in the metal solution to form Al3Ti, TiB2, and TiC. Al3Ti, TiB2, and TiC, as heterogeneous nucleation phases of α-Al, can precipitate before α-Al begins to solidify and provide nucleation sites for the subsequent growth of α-Al. However, in aluminum-silicon alloys, when the silicon content exceeds 3wt.%, poisoning occurs, that is, Ti atoms will preferentially combine with Si atoms to form TiSi compounds, and the surface of TiB2 and TiC will be covered by a layer of Si atoms, resulting in an increase in the interfacial energy and mismatch between TiB2, TiC, and α-Al. At this time, TiB2 and TiC can no longer provide nucleation sites for the growth of α-Al. Although Al3Ti, TiB2, and TiC cannot produce heterogeneous nucleation due to silicon poisoning, Ti atoms can restrict the growth of α-Al during its growth, thereby achieving the effect of α-Al grain refinement. However, this grain refinement effect is limited. Therefore, in order to improve the efficiency of grain refiners, it is necessary to provide new heterogeneous nucleation phases for the growth of α-Al in aluminum-silicon alloys.

[0004] For decades, scientists have devoted significant effort to preventing silicon poisoning in aluminum-silicon alloys. However, a definitive solution remains elusive. Some researchers have attempted to mitigate the poisoning effect by varying the Ti:B ratio, such as in Al-3Ti-3B and Al-3Ti-1B, increasing the content of refiners, and exploring new master alloys, such as Al-Ti-BC, Al-Ti-Nb-B, and Al-Nb-B. However, these efforts have not completely resolved the silicon poisoning problem in aluminum-silicon alloys.

[0005] Patent number CN 114717453 A discloses a high-strength and tough cast aluminum-silicon alloy. During the preparation of the aluminum-silicon alloy, an Al-Ti-C-CuO mixed powder is added, which reacts in the melt to generate a large number of small and uniform TiC ceramic particles. The eutectic silicon phase is effectively modified with the help of rare earth elements Eu and La. This technology improves the toughness and plasticity of the material by changing the morphology of the silicon phase and reducing stress concentration at the tip of the silicon phase.

[0006] Patent number CN 104328300 B discloses a method for preparing a refiner for scrap aluminum can alloy. The refiner, Al-Ti-Sc, can not only refine the cast grains and dendrite structure to meet the requirements for recycling and grade preservation of scrap aluminum can alloy, but also significantly increase the recrystallization temperature of the can plate. Summary of the Invention

[0007] The present invention overcomes the deficiencies of the prior art and provides an Al-Sc-Ti grain refiner capable of resisting silicon poisoning and application thereof.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions.

[0009] An Al-Sc-Ti grain refiner capable of resisting silicon poisoning, wherein the chemical composition and mass percentage of the grain refiner are Sc: 10-50wt.%; Ti: 3-10wt.%; and the balance is Al.

[0010] Preferably, the mass ratio of Sc to Ti is ≥3.

[0011] More preferably, the mass ratio of Sc to Ti is 5:1.

[0012] Preferably, the method for preparing the grain refiner comprises the following steps:

[0013] 1) Prepare the ingredients according to the designed Al-Sc-Ti grain refiner: weigh the required Sc-containing material, Ti-containing material and Al-containing material according to the mass ratio;

[0014] 2) Melting: Place the weighed raw materials into the melting furnace, melt them into liquid metal, and stir them thoroughly to form a melt;

[0015] 3) pouring the melt into a mold and solidifying it to form a grain refiner.

[0016] More preferably, the smelting temperature in step 2) is greater than 650° C., and after the smelting is completed, the holding time is ≥ 0.5 h, and stirring and slagging are performed to form a fully reacted melt.

[0017] The invention discloses an Al-Sc-Ti grain refiner capable of resisting silicon poisoning, which is used for grain refinement of aluminum-silicon alloy.

[0018] An application of an Al-Sc-Ti grain refiner capable of resisting silicon poisoning comprises the following steps:

[0019] 1) Weigh the aluminum-silicon alloy to be refined, dry it, and then heat and melt it;

[0020] 2) Calculate and weigh the required Al-Sc-Ti grain refiner according to mass percentage, dry it, and add it to the aluminum-silicon alloy melt;

[0021] 3) After the Al-Sc-Ti grain refiner is completely melted, degassing and slag removal are carried out, and then the aluminum-silicon alloy melt is poured into the mold. After cooling, the desired casting is obtained.

[0022] Preferably, the mass of Sc in the added Al—Sc—Ti grain refiner is ≥ 0.5 wt.% of the mass of the aluminum-silicon alloy to be refined.

[0023] The beneficial effects of the present invention compared to the prior art are:

[0024] In the grain refiner prepared by the present invention, the Sc content is greater than three times the Ti content. When the new Al-Sc-Ti grain refiner is introduced into the aluminum-silicon alloy, a new heterogeneous nucleation phase (Al, Si)3(Ti, Sc) is formed in the solution and serves as a nucleation site for α-Al. The generation of the new heterogeneous nucleation phase (Al, Si)3(Ti, Sc) greatly refines the α-Al grains in the aluminum-silicon alloy, greatly improving the efficiency of the grain refiner. At the same time, the new heterogeneous nucleation phase (Al, Si)3(Ti, Sc) is not affected by the Si in the aluminum-silicon alloy, avoiding the effects of silicon poisoning in the aluminum-silicon alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the metallographic image of the ZL114A alloy grains with 20g of Al-10Ti grain refiner added.

[0026] Figure 2 This is the metallographic image of the ZL114A alloy grains with 100g of Al-5Sc-1Ti grain refiner added.

[0027] Figure 3 This is the metallographic image of the ZL114A alloy grains with 140g of Al-5Sc-1Ti grain refiner added. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. The technical solutions of the present invention will be described in detail below with reference to the embodiments and the accompanying drawings, but the scope of protection is not limited thereto.

[0029] Example 1

[0030] A method for preparing an Al-5Sc-1Ti grain refiner comprises the following steps:

[0031] Ingredients: Weigh 200g of Al-10Sc master alloy, 40g of Al-10Ti master alloy, and 165g of pure aluminum, dry them, heat and melt them, and stir them thoroughly after melting into metal liquid to form a fully reacted melt; pour the fully reacted melt into a mold and solidify it to form a refiner alloy material Al-5Sc-1Ti.

[0032] Example 2

[0033] An application method of an Al-5Sc-1Ti grain refiner comprises the following steps:

[0034] 1000g of ZL114A alloy was weighed, dried, and then heated to melt. Once completely melted, 100g of the Al-5Sc-1Ti grain refiner prepared as in Example 1 was weighed and placed into the molten metal. After the grain refiner was completely melted, degassing and slag removal were performed. After standing for 20 minutes, the molten metal was poured into a mold and cooled to obtain the desired casting.

[0035] Under the same conditions, 1000g of ZL114A alloy with 20g of Al-10Ti grain refiner was cast as a comparison. According to statistics, the grain size of ZL114A alloy with 20g of Al-10Ti grain refiner is 545.5μm (see Figure 1 ), while the grain size of ZL114A alloy with 100g of Al-5Sc-1Ti grain refiner is 219.2μm (see Figure 2 ). It can be seen that the Al-Sc-Ti grain refiner prepared in Example 1 has a greater improvement than the traditional Al-10Ti grain refiner.

[0036] Example 3

[0037] An application method of an Al-5Sc-1Ti grain refiner comprises the following steps:

[0038] 1000g of ZL114A alloy was weighed, dried, and then heated to melt. Once completely melted, 140g of the Al-5Sc-1Ti grain refiner prepared as in Example 1 was weighed. After complete drying, the alloy was placed into the molten metal. After the grain refiner was completely melted, degassing and slag removal were performed. After standing for 20 minutes, the molten metal was poured into a mold and cooled to obtain the desired casting.

[0039] Under the same conditions, 1000g of ZL114A alloy with 20g of Al-10Ti grain refiner was cast as a comparison. According to statistics, the grain size of ZL114A alloy with 20g of Al-10Ti grain refiner is 545.5μm (see Figure 1 ), while the grain size of ZL114A alloy with 140g of Al-5Sc-1Ti grain refiner is 153.8μm (see Figure 3 ), it can be seen that the Al-Sc-Ti grain refiner prepared in Example 1 has a significant improvement over the traditional Al-10Ti grain refiner. At the same time, as the addition amount of Al-Sc-Ti grain refiner increases, the grain refining effect on the aluminum-silicon alloy is also significantly improved.

[0040] Example 4

[0041] A method for preparing an Al-5Sc-1Ti grain refiner comprises the following steps:

[0042] Ingredients: Weigh 120g of Al-10Sc master alloy, 40g of Al-10Ti master alloy, and 165g of pure aluminum, dry them, heat and melt them, and stir them thoroughly after melting into metal liquid to form a fully reacted melt; pour the fully reacted melt into a mold and solidify it to form a refiner alloy material Al-3Sc-1Ti.

[0043] Example 5

[0044] A method for preparing an Al-5Sc-1Ti grain refiner comprises the following steps:

[0045] Ingredients: Weigh 120g of Al-10Sc master alloy, 30g of Al-10Ti master alloy, and 1000g of pure aluminum, dry them, heat and melt them, and stir them thoroughly after melting into metal liquid to form a fully reacted melt; pour the fully reacted melt into a mold and solidify it to form a refiner alloy material Al-4Sc-1Ti.

[0046] Example 6

[0047] A method for preparing an Al-5Sc-1Ti grain refiner comprises the following steps:

[0048] Ingredients: Weigh 120g of Al-10Sc master alloy, 12g of Al-10Ti master alloy, and 268g of pure aluminum, dry them, heat and melt them, and stir them thoroughly after melting into metal liquid to form a fully reacted melt; pour the fully reacted melt into a mold and solidify it to form a refiner alloy material Al-10Sc-1Ti.

[0049] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be considered that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the present invention, which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims

1. Application of an Al-Sc-Ti grain refiner resistant to silicon poisoning, characterized in that: Preparation method of Al-5Sc-1Ti grain refiner The following steps are involved: Ingredients: Weigh 200g of Al-10Sc master alloy, 40g of Al-10Ti master alloy, and 165g of pure aluminum, dry them, heat and melt them, and stir them thoroughly to form a fully reacted melt. Pour the fully reacted melt into a mold and solidify it to form a refiner alloy material Al-5Sc-1Ti. The Al-5Sc-1Ti grain refiner is used for grain refinement of aluminum-silicon alloy: 1000g of ZL114A alloy is weighed, dried, and then heated to melt. After it is completely melted, 140g of the prepared Al-5Sc-1Ti grain refiner is weighed; after it is completely dried, it is placed in the metal liquid. After the grain refiner is completely melted, degassing and slag removal operations are performed. After standing for 20 minutes, the metal melt is poured into a mold and cooled to obtain the desired casting.

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