CN101805860B - Spherical silicon phase aluminum-silicon alloy and technological method thereof - Google Patents

Abstract

The invention relates to a spherical silicon phase aluminum-silicon alloy and a technological method thereof. The alloy is characterized in that: (1) the Si content of the alloy is between 11 and 30 weight percent; spherical silicon phases are distributed in an aluminum substrate; and elements of Cu, Mg, Mn and the like can be added into the aluminum substrate for intensifying; and (2) alloying technology is characterized by comprising the following steps: founding an aluminum-silicon alloy melt with the Si content of about 4 weight percent; pouring the founded melt into a quantitative suspension pouring cup with a controllable temperature; implanting clean silicon particles of between 2 and 10 mu m by using clean argon gas or other inert gas; after the silicon is implanted, continually introducing the argon gas and stirring the melt for 10 to 30 seconds; and immediately pouring the melt from a pouring gate at the bottom of the suspension pouring cup into a metal mold with negative pressure to obtain a cast product or a cast ingot. The silicon in the aluminum-silicon alloy is a fine spherical phase, and the size, appearance and quantity of the silicon phase are easy to control, so the intensity and plasticity of the alloy are greatly enhanced and simple process and low cost are achieved.

Description

Spherical silicon-phase aluminum-silicon alloy and process method thereof

technical field

The invention relates to a spherical silicon-phase aluminum-silicon alloy and a process method thereof, belonging to the technical field of metal material preparation, in particular to aluminum-silicon alloy casting.

Background technique

Aluminum-silicon series casting alloy has the characteristics of low density, high specific strength, small thermal expansion coefficient, excellent wear resistance and corrosion resistance, and high temperature performance, and has good casting performance. It is widely used in automobiles, machinery and other industries. Ideal material for components such as pistons, cylinder blocks, and swash plates. With the increase of silicon content, the properties such as high-temperature strength are more excellent, and aluminum-silicon alloy has become one of the most valued structural materials in the manufacturing industry.

However, since the cooling rate of aluminum-silicon alloy is limited during the casting process, the microstructure is mainly composed of primary phase α-Al and eutectic structure (α-Al+Si) or primary silicon and eutectic structure. Among them, silicon has a significant impact on a series of properties of the alloy, and the silicon phase in the alloy is generally in the shape of a thick plate (primary silicon) or needle (eutectic silicon). Therefore, at home and abroad, various methods of refining or spheroidizing have been researched on changing the morphology of silicon to improve the microstructure of the alloy. Although the chemical modification agent treatment can change the morphology of the silicon phase in the aluminum-silicon alloy, it is difficult to make it spherical, and the size of the silicon phase is also relatively large, which is difficult to be smaller than 10 μm. Semi-solid technology, spray deposition, and solid-liquid mixed casting technology are currently the main methods with great application value. The solid-liquid mixed casting technology combines the characteristics of semi-solid casting and spray deposition. It is to add aluminum-silicon alloy powder with the same composition or close composition to the overheated aluminum-silicon alloy melt, and make the melt and The powder is mixed uniformly and solidified rapidly, and the average particle size of the silicon phase can be controlled below 5 μm (Chen Zhenhua, Yan Hongge, Kang Zhitao, etc., CN1262334A, August 9, 2000). However, due to the addition of alloy powders with the same composition or similar composition, the melting point is low and it is easy to melt, and complex electromagnetic or mechanical stirring systems are required for strong stirring to solve problems such as uniform distribution, and the control difficulty and cost are still high.

Contents of the invention

The purpose of the present invention is to provide a spherical silicon-phase aluminum-silicon alloy and its process method, that is: first melt the aluminum-silicon alloy melt with a Si content of about 4%, and add Cu, Mg, Mn and other strengthening elements to Aluminum matrix for reinforcement. Implant silicon particles into the melt through argon or other inert gases in a suspended sprue cup with controllable temperature, and then pour into a metal mold with negative pressure. After solidification, spherical silicon-phase aluminum-silicon alloy castings or castings are obtained. Ingot, the spherical silicon phase is uniformly distributed in the aluminum matrix, and its size and quantity vary with the size and quantity of implanted silicon particles, and the size is between 2-10 μm. The alloy has high strength and high toughness. The process is simple and easy to control, thereby overcoming the deficiencies of the prior art.

The technical solution of the present invention is a spherical silicon-phase aluminum-silicon alloy and its process method. The Si content in the alloy is 11-30 wt%, and the silicon is uniformly distributed in the aluminum matrix in the form of a fine spherical silicon phase, and the size of the spherical silicon phase is between 2-10 μm. Between, and Cu, Mg, Mn and other strengthening elements can be added to strengthen the aluminum matrix. This is achieved through the following process methods.

(1) First, an aluminum-silicon alloy melt with a Si content of about 4wt% is melted, and strengthening elements such as Cu, Mg, and Mn, which strengthen the aluminum matrix, may be added.

(2) It is poured into a temperature-controllable quantitative suspension sprue cup, and the melt temperature is controlled at 100-150° C. above the liquidus line. Then clean silicon particles are implanted with pure argon or other inert gas, the pressure of argon or other inert gas is 10-20MPa, the implanted amount of silicon particles is 7-26wt%, and the particle size is 2-10μm. Before implantation, carry out cleaning treatment under the conditions of 300-400°C and vacuum degree not lower than 4.0×10 ^-3 Pa.

(3) After silicon implantation, continue to pass through the argon gas to stir the melt for 10-30 seconds, and immediately pour the melt from the sprue at the bottom of the suspended sprue cup into a metal mold with negative pressure to obtain castings or ingots. The negative pressure of the metal type is not lower than 8.5×10 ^-2 Pa.

The advantages of the present invention are:

(1) The spherical silicon-phase aluminum-silicon alloy of the present invention has good comprehensive mechanical properties. The spherical silicon phase aluminum-silicon alloy structure is composed of an aluminum matrix and a uniformly distributed fine spherical silicon phase. The spherical silicon phase in the alloy is formed by implanting prefabricated silicon particles, and the silicon particles are melted in the alloy melt with sharp corners. Passivation further promotes the formation of spherical silicon phase, controlling the crystallization and solidification process to obtain a spherical silicon phase of 2-10 μm, its size and quantity can vary with the size and quantity of implanted silicon particles, so that the alloy has high strength while , and has high toughness.

(2) The process is simple and easy to control. The silicon particles are implanted with argon gas. While the silicon particles are implanted, the argon gas can also refine, stir and protect the melt, and mix evenly. The particle size and implantation amount of prefabricated silicon particles are easy to control, and spherical silicon phases of corresponding sizes are obtained after implanting into the melt, so that it is easy to control the size and quantity of spherical silicon phases in the alloy.

(3) No pollution to the alloy, energy saving and material saving. The invention does not use mechanical or electromagnetic stirring in the process of alloy smelting and silicon particle implantation, has no complicated mechanical or electromagnetic stirring system, and does not need to add various modifiers.

Description of drawings

Figure 1 is the as-cast structure (200×) of a spherical silicon-phase aluminum-silicon alloy. The chemical composition is (wt%): Si11.6, adding Cu 1.61, Mg 0.52, Mn 0.83 to strengthen the alloy aluminum matrix. The as-cast structure of the alloy is dense, and the spherical silicon phase is evenly distributed in the alloy matrix, with a size of about 5-8 μm. The particle size of the implanted silicon particles ranges from 5-10 μm, and the implanted amount is about 8% of the amount of the alloy melt.

Fig. 2 is the as-cast structure (200×) of spherical silicon-phase aluminum-silicon alloy. The chemical composition is (wt%): Si 26.3, without adding Cu, Mg, Mn, etc., which are strengthening elements for the alloy aluminum matrix. The as-cast structure of the alloy is similar to that in Figure 1, and the number of silicon phases is more than that in Figure 1, which is still uniformly distributed in the alloy matrix, and the size is below 5 μm. The silicon particle size of the implanted silicon particles ranges from 2-5 μm, and the implanted amount is about 24% of the amount of the alloy melt.

Detailed ways

The substantive features and remarkable progress of the present invention will be further elaborated below through specific implementation examples. But the present invention is not limited to this implementation case.

Example 1: Preparation of a spherical silicon-phase aluminum-silicon alloy with a silicon content of 12 wt%

First, an aluminum-silicon alloy melt with a Si content of about 4wt% is melted, and Cu 1.61, Mg 0.52, and Mn 0.83 strengthening elements for strengthening the aluminum matrix are added. It is poured into a temperature-controllable quantitative suspension sprue cup, and the melt temperature is controlled at 100-150°C above the liquidus line. Then use pure argon gas to implant clean silicon particles, the pressure of argon gas is 10MPa, the implanted amount of silicon particles is about 8wt% of the alloy melt, and the particle size range is 5-10μm. Carry out cleaning treatment under the condition that the vacuum degree is not lower than 4.0×10 ^-3 Pa. After the silicon is implanted, continue to pass through the argon gas to stir the melt for 10-30 seconds, and immediately pour the melt from the sprue at the bottom of the suspended sprue cup into the metal mold with negative pressure to obtain castings or ingots, the negative pressure metal mold The negative pressure is 7.4×10 ^-2 Pa. The chemical composition of the obtained spherical phase aluminum-silicon alloy casting or ingot is (wt%): Si11.6, Cu1.61, Mg0.52, Mn0.83.

The tensile test was carried out on the SHT4305 universal testing machine. The tensile strength σ _b = 377MPa and the elongation δ = 4.3% of the alloy T6 after treatment were much higher than the equivalent brand ZL108 alloy obtained by the ordinary casting method (σ _b = 261MPa, elongation δ =0.4%, T6 treatment) mechanical properties, high toughness. According to the metallographic analysis, the alloy structure is dense, and the spherical silicon phase is evenly distributed in the alloy matrix, with a size of about 5-8 μm.

Example 2: Preparation of a high-silicon spherical silicon-phase aluminum-silicon alloy with a silicon content of 27wt%

First, an aluminum-silicon alloy melt with a Si content of about 4wt% is melted, and poured into a temperature-controllable quantitative suspension sprue cup, and the melt temperature is controlled at 100-150° C. above the liquidus line. Then use pure argon gas to implant clean silicon particles, the pressure of argon gas is 10MPa, the implanted amount of silicon particles is about 24wt% of the alloy melt, and the particle size range of implanted silicon particles is 2-5μm. Carry out cleaning treatment under the condition of -400℃ and vacuum not lower than 4.0×10 ^-3 Pa. After the silicon is implanted, continue to pass through the argon gas to stir the melt for 10-30 seconds, and immediately pour the melt from the sprue at the bottom of the suspended sprue cup into the metal mold with negative pressure to obtain castings or ingots, the negative pressure metal mold The negative pressure is not lower than 7.4×10 ^-2 Pa.

The tensile test was carried out on the SHT4305 universal testing machine. The tensile strength of the alloy σ _b = 184MPa, the elongation δ = 6.6%, much higher than the aluminum-silicon alloy with a silicon content of 27% obtained by the ordinary casting method (σ _b = 38MPa, Elongation δ = 0%) mechanical properties, high strength and toughness. Metallographic analysis shows that the structure of the alloy is dense, and the spherical silicon phase is evenly distributed in the alloy matrix, with a size of about 2-4 μm.

Claims (1)

1. A spherical silicon-phase aluminum-silicon alloy, characterized in that: the Si content in the spherical silicon-phase aluminum-silicon alloy is 11-30wt%, silicon becomes a fine spherical silicon phase and is distributed in the aluminum matrix, and the size of the spherical silicon phase is 2- 10 μm, and adding Cu, Mg, and Mn strengthening elements to strengthen the aluminum matrix, the preparation method of the spherical silicon-phase aluminum-silicon alloy is as follows: (1) first melting the aluminum-silicon alloy melt containing 4wt% Si, and adding Cu, Mg, and Mn strengthening elements that strengthen the aluminum matrix; (2) Pour it into a temperature-controllable quantitative suspension sprue cup. The melt temperature is controlled at 100-150°C above the liquidus line, and then clean silicon particles are implanted with pure argon or other inert gases. Argon or The pressure of other inert gases is 10-20MPa, the implantation amount of silicon particles is 7-26wt%, the particle size is 2-10μm, and the conditions before implantation are 300-400℃ and the vacuum degree is not lower than 4.0×10 ^-3 Pa Under the cleaning treatment; (3) After silicon implantation, continue to pass through the argon gas to stir the melt for 10-30 seconds, and immediately pour the melt from the sprue at the bottom of the suspended sprue cup into a metal mold with negative pressure to obtain castings or ingots. The negative pressure of the metal type is not lower than 8.5×10 ^-2 Pa.

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