阅读说明：本技术 一种含Ag、Ca的AZ91镁合金及其制备方法 (AZ91 magnesium alloy containing Ag and Ca and preparation method thereof ) 是由 周晓雷 晏昊立 王晓民 张闯 王云鹏 于 2021-09-16 设计创作，主要内容包括：本发明涉及一种含Ag、Ca的AZ91镁合金及其制备方法,属于金属材料技术领域。分别对AZ91镁合金和石墨坩埚进行加热干燥处理；然后将AZ91镁合金置于石墨坩埚中,通入CO-(2)和SF-(6)的混合气体,加热到温度为750℃使合金完全熔化并加入Ag、Ca,搅拌均匀得到熔融体；将得到的熔融体继续精炼,降温保温；降温出渣得到精炼熔融体；将得到的精炼熔融体浇铸预热后的金属模具中,待冷却后,开模取出,得到含Ag、Ca的AZ91镁合金。经本方法在AZ91镁合金的基础上添加少量的Ag、Ca,形成Ag-Ca合金而生成的产物,弥散分布在镁基体表面,这些数量之多的细小微粒均匀分布于基体中,提高了AZ91镁合金的力学性能。(The invention relates to an AZ91 magnesium alloy containing Ag and Ca and a preparation method thereof, belonging to the technical field of metal materials. Respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible; then placing the AZ91 magnesium alloy into a graphite crucible, and introducing CO 2 And SF 6 Heating the mixed gas to 750 ℃ to completely melt the alloy, adding Ag and Ca, and uniformly stirring to obtain a molten mass; refining the obtained molten mass, cooling and preserving heat; cooling and deslagging to obtain a refined molten mass; and casting the obtained refined molten mass into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca. By the method, a small amount of Ag and Ca is added on the basis of AZ91 magnesium alloy to form a product of Ag-Ca alloy, the product is dispersed and distributed on the surface of a magnesium matrix, and the large amount of fine particles are uniformly distributedIn the matrix, the mechanical property of the AZ91 magnesium alloy is improved.)

1. An AZ91 magnesium alloy containing Ag and Ca, which is characterized in that: comprises the following components in percentage by mass: 0.3 to 3 percent of Ags, 0.3 to 3 percent of Ca0 percent, and the balance of AZ91 magnesium alloy, wherein the sum of the Ag, the Ca and the AZ91 magnesium alloy is 100 percent.

2. The preparation method of the AZ91 magnesium alloy containing Ag and Ca according to claim 1, which is characterized by comprising the following specific steps:

(1) respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible;

(2) then placing the AZ91 magnesium alloy into a graphite crucible, and introducing CO₂And SF₆Heating the mixed gas to 750 ℃ to completely melt the alloy, adding Ag and Ca, and uniformly stirring to obtain a molten mass;

(3) continuously heating the molten mass obtained in the step (2) to 765-785 ℃, introducing Ar gas for refining for 30-45 min; then cooling to the temperature of 700-; continuously cooling to 680 ℃, and deslagging to obtain a refined molten mass;

(4) and (4) casting the refined molten mass obtained in the step (3) into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca.

3. The method for preparing AZ91 magnesium alloy containing Ag and Ca according to claim 2, wherein the method comprises the following steps: in the step (1), the heating and drying temperature of the AZ91 magnesium alloy is 450 ℃.

4. The method for preparing AZ91 magnesium alloy containing Ag and Ca according to claim 2, wherein the method comprises the following steps: the heating and drying temperature of the graphite crucible in the step (1) is 200 ℃.

5. The method for preparing AZ91 magnesium alloy containing Ag and Ca according to claim 2, wherein the method comprises the following steps: CO in said step 2₂And SF₆The volume ratio is 99: 1.

6. the method for preparing AZ91 magnesium alloy containing Ag and Ca according to claim 2, wherein the method comprises the following steps: the flow rate of Ar gas in the step (3) is 8-12L/min.

Technical Field

The invention relates to an AZ91 magnesium alloy containing Ag and Ca and a preparation method thereof, belonging to the technical field of metal materials.

Background

The magnesium alloy is an alloy formed by adding other elements on the basis of magnesium. The method is characterized in that: small density, high strength, large elastic modulus, good shock absorption, larger impact load bearing capacity than aluminum alloy, and good organic matter and alkali corrosion resistance. The main alloy elements comprise aluminum, zinc, manganese, cerium, thorium, a small amount of zirconium or cadmium and the like. Currently, the most widely used are magnesium-aluminum alloys, followed by magnesium-manganese alloys and magnesium-zinc-zirconium alloys. The method is mainly used in aviation, aerospace, transportation, chemical engineering, rocket and other industrial departments.

However, the magnesium alloy has the disadvantage of low strength, and the application range is greatly limited. Therefore, the disadvantages of magnesium alloys are to be improved as much as possible while taking advantage of the advantages of magnesium alloys. And the addition of other elements to magnesium alloys may serve to improve the properties of the alloys, such as AZ91 magnesium alloy.

The AZ91 magnesium alloy is processed mainly by a mode of pressure die casting assisted with post processing, A represents metal aluminum Al, Z represents metal zinc Zn, 9 represents that the content of aluminum is 9 percent, and 1 represents that the content of zinc is 1 percent, and the AZ91 magnesium alloy is characterized by high specific strength and is mainly used for shells of electric products, small-size thin or special-shaped brackets and the like. AZ91 belongs to the class of cast magnesium alloys, and can be modified in appearance by surface means such as electrophoresis.

Because the mechanical properties of the alloy are closely related to the matrix structure, the properties (such as hardness, strength and the like), the shape, the size, the distribution, the volume fraction and the like of the second phase. When the alloy is stretched, the hard and brittle phases in the alloy are generally difficult to plastically deform, so that stress concentration is generated around the hard phases, and cracks can be initiated and propagated in the hard phases firstly; meanwhile, the coarse hard and brittle phases can also crack the matrix, stress concentration is easily generated in the stretching process, and cracks are generated and spread along the interface of the second phase and the matrix grains. As a result of the two actions, the brittleness of the alloy material is increased, the alloy sample is subjected to early fracture, and the mechanical property of the material is reduced.

Disclosure of Invention

Aiming at the problems and the defects of the prior art, the invention provides the AZ91 magnesium alloy containing Ag and Ca and the preparation method thereof. According to the method, a small amount of Ag and Ca is added on the basis of the AZ91 magnesium alloy to form a product of Ag-Ca alloy, the product is dispersed and distributed on the surface of a magnesium matrix, and a large amount of fine particles are uniformly distributed in the matrix, so that the magnesium matrix is obviously strengthened, and the mechanical property of the AZ91 magnesium alloy is improved. The invention is realized by the following technical scheme.

An AZ91 magnesium alloy containing Ag and Ca comprises the following components in percentage by mass: 0.3 to 3 percent of Ags, 0.3 to 3 percent of Ca0 percent, and the balance of AZ91 magnesium alloy, wherein the sum of the Ag, the Ca and the AZ91 magnesium alloy is 100 percent.

A preparation method of AZ91 magnesium alloy containing Ag and Ca comprises the following specific steps:

(1) respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible;

(2) then placing the AZ91 magnesium alloy into a graphite crucible, and introducing CO₂And SF₆Heating the mixed gas to 750 ℃ to completely melt the alloy, adding Ag and Ca, and uniformly stirring to obtain a molten mass;

(3) continuously heating the molten mass obtained in the step (2) to 765-785 ℃, introducing Ar gas for refining for 30-45 min; then cooling to the temperature of 700-; continuously cooling to 680 ℃, and deslagging to obtain a refined molten mass;

(4) and (4) casting the refined molten mass obtained in the step (3) into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca.

In the step (1), the heating and drying temperature of the AZ91 magnesium alloy is 450 ℃.

The heating and drying temperature of the graphite crucible in the step (1) is 200 ℃.

CO in said step 2₂And SF₆In a volume ratio of99: 1, the introduction amount of the mixed gas is 0.1-0.5m³/h。

The flow rate of Ar gas in the step (3) is 8-12L/min.

The main reason that the hardness can be increased by adding Ca into the AZ91 magnesium alloy is caused by the fine crystal strengthening effect generated by the grain refinement of an alpha-Mg matrix; at the same time, coarse lamellar AgCa phase and coarse reticular beta-Mg₁₇Al₁₂The phases are gradually broken and relatively thinned, and certain contribution is made to improvement of tensile strength; in addition, a fine AgCa phase is precipitated along the grain boundaries, and can pin the grain boundaries and inhibit dislocation movement.

Therefore, a small amount of Ag and Ca is added on the basis of the AZ91 magnesium alloy to form a product of Ag-Ca alloy, the product is dispersed and distributed on the surface of the magnesium matrix, and the fine particles with large amount are uniformly distributed in the matrix, thereby playing a remarkable strengthening role for the magnesium matrix again and improving the mechanical property of the AZ91 magnesium alloy. It would be a meaningful attempt to use magnesium alloy materials on the furnace throat.

The invention has the beneficial effects that:

a small amount of Ag and Ca is added on the basis of AZ91 magnesium alloy to form a product of Ag-Ca alloy, the product is dispersed and distributed on the surface of a magnesium matrix, and the large amount of fine particles are uniformly distributed in the matrix, so that the magnesium matrix is obviously strengthened again, and the mechanical property of the AZ91 magnesium alloy is improved.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The invention is further described with reference to the following drawings and detailed description.

Example 1

The AZ91 magnesium alloy containing Ag and Ca comprises the following components in percentage by mass: 0.5 percent of Ag0, 0.5 percent of Ca0, the balance of AZ91 magnesium alloy, and the sum of Ag, Ca and AZ91 magnesium alloy is 100 percent.

As shown in fig. 1, the preparation method of the AZ91 magnesium alloy containing Ag and Ca comprises the following specific steps:

(1) respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible; heating and drying AZ91 magnesium alloy at 450 deg.C for 40 min; heating and drying the graphite crucible at 200 ℃ for 40 min;

(2) then 99gAZ91 magnesium alloy is put into a graphite crucible and CO is introduced₂And SF₆Mixed gas (mixed gas inlet amount is 0.1 m)³H), heating to 750 ℃ to completely melt the alloy, adding 0.5g of Ag and 0.5g of 0.5gCa, and uniformly stirring to obtain a molten mass; CO 2₂And SF₆The volume ratio is 99: 1;

(3) continuously heating the molten mass obtained in the step (2) to 765 ℃, introducing Ar gas (the flow of the Ar gas is 8L/min), and refining for 30 min; then cooling to 700 ℃ and preserving the temperature for 60 min; continuously cooling to 680 ℃, and deslagging to obtain a refined molten mass;

(4) and (4) casting the refined molten mass obtained in the step (3) into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca.

The AZ91 magnesium alloy containing Ag and Ca obtained in the example has hardness values of 75HV, 77HV and 76HV at three measuring points on a sample, the average value is 76HV, the applied load is 1.0, and the loading time is 10 s; compared with the pure AZ91 magnesium alloy with the hardness of 71 HV, the hardness is obviously improved.

Example 2

The AZ91 magnesium alloy containing Ag and Ca comprises the following components in percentage by mass: ag1%, Ca1%, and the balance of AZ91 magnesium alloy, wherein the sum of the Ag, the Ca and the AZ91 magnesium alloy is 100%.

As shown in fig. 1, the preparation method of the AZ91 magnesium alloy containing Ag and Ca comprises the following specific steps:

(1) respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible; heating and drying AZ91 magnesium alloy at 450 deg.C for 40 min; heating and drying the graphite crucible at 200 ℃ for 40 min;

(2) then 98gAZ91 magnesium alloy is put into a graphite crucible and CO is introduced₂And SF₆Mixed gas (mixed gas inlet amount is 0.5 m)³H), heating to 750 ℃ to completely melt the alloy, adding 1gAg and 1gCa, and stirringUniformly stirring to obtain a molten mass; CO 2₂And SF₆The volume ratio is 99: 1;

(3) continuously heating the molten mass obtained in the step (2) to 765 ℃, introducing Ar gas (the flow of the Ar gas is 12L/min), and refining for 30 min; then cooling to 700 ℃ and preserving the temperature for 60 min; continuously cooling to 680 ℃, and deslagging to obtain a refined molten mass;

(4) and (4) casting the refined molten mass obtained in the step (3) into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca.

The AZ91 magnesium alloy containing Ag and Ca obtained in the example has hardness values of 81HV, 79HV and 80HV at three measurement points on the sample, the average value is 80HV, the applied load is 1.0, and the loading time is 10 s, so that the hardness is obviously improved compared with the pure AZ91 magnesium alloy with the hardness of 71 HV.

Example 3

The AZ91 magnesium alloy containing Ag and Ca comprises the following components in percentage by mass: 1.5 percent of Ags, 1.5 percent of Ca1, the balance of AZ91 magnesium alloy, and the sum of Ag, Ca and AZ91 magnesium alloy is 100 percent.

As shown in fig. 1, the preparation method of the AZ91 magnesium alloy containing Ag and Ca comprises the following specific steps:

(1) respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible; heating and drying AZ91 magnesium alloy at 450 deg.C for 40 min; heating and drying the graphite crucible at 200 ℃ for 40 min;

(2) then 97gAZ91 magnesium alloy is put into a graphite crucible and CO is introduced₂And SF₆Mixed gas (mixed gas inlet amount is 0.2 m)³H), heating to 750 ℃ to completely melt the alloy, adding 1.5g of Ag and 1.5g of 1.5gCa, and uniformly stirring to obtain a molten mass; CO 2₂And SF₆The volume ratio is 99: 1;

(3) continuously heating the molten mass obtained in the step (2) to 765 ℃, introducing Ar gas (the flow of the Ar gas is 10L/min), and refining for 30 min; then cooling to 700 ℃ and preserving the temperature for 60 min; continuously cooling to 680 ℃, and deslagging to obtain a refined molten mass;

(4) and (4) casting the refined molten mass obtained in the step (3) into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca.

The AZ91 magnesium alloy containing Ag and Ca obtained in the example has hardness values of 85HV, 86HV and 86HV at three measurement points on the sample, the average value is 85.7HV, the applied load is 1.0, and the loading time is 10 s, so that the hardness is obviously improved compared with that of a pure AZ91 magnesium alloy with the hardness of 71 HV.

Example 4

The AZ91 magnesium alloy containing Ag and Ca comprises the following components in percentage by mass: ag2%, Ca2%, and the balance of AZ91 magnesium alloy, wherein the sum of the Ag, the Ca and the AZ91 magnesium alloy is 100%.

As shown in fig. 1, the preparation method of the AZ91 magnesium alloy containing Ag and Ca comprises the following specific steps:

(1) respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible; heating and drying AZ91 magnesium alloy at 450 deg.C for 40 min; heating and drying the graphite crucible at 200 ℃ for 40 min;

(2) then 96gAZ91 magnesium alloy is put into a graphite crucible and CO is introduced₂And SF₆Mixed gas (mixed gas inlet amount is 0.3 m)³Heating to 750 ℃ to completely melt the alloy, adding 2gAg and 2gCa, and uniformly stirring to obtain a molten mass; CO 2₂And SF₆The volume ratio is 99: 1;

(3) continuously heating the molten mass obtained in the step (2) to 785 ℃, introducing Ar gas (the flow of the Ar gas is 11L/min), and refining for 45 min; then cooling to 720 ℃ and preserving the temperature for 30 min; continuously cooling to 680 ℃, and deslagging to obtain a refined molten mass;

(4) and (4) casting the refined molten mass obtained in the step (3) into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca.

The AZ91 magnesium alloy containing Ag and Ca obtained in the example has hardness values of 89HV, 88HV and 89HV at three measurement points on the sample, the average value is 88.7HV, the applied load is 1.0, and the loading time is 10 s, so that the hardness is obviously improved compared with that of a pure AZ91 magnesium alloy with the hardness of 71 HV.

Example 5

The AZ91 magnesium alloy containing Ag and Ca comprises the following components in percentage by mass: ag2.5 percent, Ca2.5 percent, the balance of AZ91 magnesium alloy, and the sum of Ag, Ca and AZ91 magnesium alloy is 100 percent.

As shown in fig. 1, the preparation method of the AZ91 magnesium alloy containing Ag and Ca comprises the following specific steps:

(1) respectively carrying out heating and drying treatment on the AZ91 magnesium alloy and the graphite crucible; heating and drying AZ91 magnesium alloy at 450 deg.C for 40 min; heating and drying the graphite crucible at 200 ℃ for 40 min;

(2) then placing the 95gAZ91 magnesium alloy in a graphite crucible, and introducing CO₂And SF₆Mixed gas (mixed gas inlet amount is 0.3 m)³H), heating to 750 ℃ to completely melt the alloy, adding 2.5g of Ag and 2.5g of 2.5gCa, and uniformly stirring to obtain a molten mass; CO 2₂And SF₆The volume ratio is 99: 1;

(3) continuously heating the molten mass obtained in the step (2) to 775 ℃, introducing Ar gas (the flow of the Ar gas is 10L/min), and refining for 40 min; then cooling to 710 ℃ and preserving the temperature for 45 min; continuously cooling to 680 ℃, and deslagging to obtain a refined molten mass;

(4) and (4) casting the refined molten mass obtained in the step (3) into a preheated metal mold, cooling, opening the mold and taking out to obtain the AZ91 magnesium alloy containing Ag and Ca.

The AZ91 magnesium alloy containing Ag and Ca obtained in the example has the hardness values of 94HV, 92HV and 93HV at three measuring points on the sample, the average value of the hardness values is 93HV, the applied load is 1.0, and the hardness is obviously improved compared with the pure AZ91 magnesium alloy with the hardness of 71 HV when the applied load is 10 s.

While the present invention has been described in detail with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit and scope of the present invention.