CN107130159B - A kind of Ignition-proof Magnesium Alloy and preparation method thereof - Google Patents

Abstract

The invention relates to a flame-retardant magnesium alloy material and a preparation method thereof, belonging to the technical field of magnesium-based alloys and their manufacture. The flame-retardant magnesium alloy material of the present invention is composed of the following components in mass percentage: Gd 8.6-10.4%, Nd 2.6-3.4%, Ce 1.6-2.9%, Al 1.1-1.5%, Sb 1.1-1.6%, Sr 0.26 ～0.38%, Ca 0.78～1.0%, the balance is Mg and unavoidable impurities. Compared with the prior art, the flame-retardant magnesium alloy material of the present invention can significantly improve its overall performance through reasonable matching of different components, especially the mechanical properties and flame-retardant properties at room temperature and high temperature are significantly improved, and its resistance The tensile strength has an abnormal temperature effect, that is, as the stretching temperature increases, the tensile strength also increases.

Description

A kind of flame retardant magnesium alloy material and preparation method thereof

technical field

The invention relates to a flame-retardant magnesium alloy material and a preparation method thereof, belonging to the technical field of magnesium-based alloys and their manufacture.

Background technique

In the existing metal structure material system, magnesium alloy has high specific strength and specific stiffness, excellent casting performance and high damping and anti-vibration performance, is easy to recycle, has environmental protection characteristics, and has a very wide application prospect. Aerospace, electronic communication, and automobile industries are favored, and it has become one of the most promising metal structural materials at present. However, the application of magnesium alloys is restricted by the following factors: First, the strength and toughness of magnesium alloys are not ideal, which limits their widespread use. The second is that magnesium alloys are very flammable. Because magnesium is relatively active, magnesium alloys are prone to oxidative combustion during smelting and processing. Generally, magnesium alloys are smelted in flame-retardant solvents or protective atmospheres. This characteristic of being easy to oxidize and burn brings great difficulties to the production, processing and treatment of alloys, which greatly hinders the wide application of magnesium alloys. Obtaining ideal high-strength flame-retardant magnesium alloys has always been an important topic in the field of magnesium alloy research. .

At present, the flux covering method and the gas protection method are generally used in the industry to solve the combustion problem in the magnesium alloy smelting process, but the existing flame retardant methods have the problems of environmental pollution and reduction of alloy properties. A lot of research has been done on flame-retardant magnesium alloys at home and abroad. Relevant literatures have reported flame-retardant magnesium alloys prepared by alloying elements such as Ca, Be, and Re, and achieved certain results. Chinese patent ZL99113861.9 "Casting flame-retardant magnesium alloy and its melting and casting process" proposes a flame-retardant magnesium alloy containing Al, Sr, Be and rare earth elements. Its ignition temperature can reach 740 ° C, but its tensile The strength is only 160MPa, and the elongation is only 2%, and its strength and elongation cannot meet the current industrial applications. Chinese patent ZL200810155894.6 "A new flame-retardant high-strength heat-resistant magnesium alloy and its preparation method" adds Al-Ca, Al-RE, Al-Sr master alloys to molten magnesium alloy AZ91D to prepare flame-retardant properties A new type of magnesium alloy with excellent mechanical properties. Patent ZL02132441.7 reports a strong and tough flame-retardant magnesium alloy whose main components are Al, Zn, Mn, RE, and Mg. At this stage, the organic combination of improving the flame retardancy of magnesium alloys and improving the microstructure and mechanical properties of magnesium alloys at room temperature and high temperature has become the focus of current scholars' research. The Chinese invention patent application with the application publication number CN104233026A discloses a heat-resistant magnesium alloy, which consists of the following components in mass percentage: 3-8% Al, 0.5-1.5% Zn, 0.1-0.7% Sr, 0.3-1.5% %CaO, balance Mg and unavoidable impurities. The tensile strength and flame retardancy of the heat-resistant magnesium alloy are difficult to meet production needs.

Contents of the invention

The object of the present invention is to provide a flame-retardant magnesium alloy material with excellent mechanical properties at room temperature and high temperature.

The present invention also provides a preparation method of the flame-retardant magnesium alloy material.

In order to achieve the above object, the technical scheme adopted by the flame-retardant magnesium alloy material of the present invention is:

A flame-retardant magnesium alloy material, which is composed of the following components in mass percentage: Gd 8.6-10.4%, Nd 2.6-3.4%, Ce 1.6-2.9%, Al 1.1-1.5%, Sb 1.1-1.6%, Sr 0.26- 0.38%, Ca 0.78～1.0%, the balance is Mg and unavoidable impurities.

The sum of the mass percentages of the impurity elements Fe, Cu and Ni is less than 0.2%.

The technical scheme adopted in the preparation method of the flame-retardant magnesium alloy material of the present invention is:

A preparation method of the above-mentioned flame-retardant magnesium alloy material, comprising the following steps:

1) melting raw materials magnesium, aluminum, strontium and antimony under the protection of a mixed gas of _CO2 and _SF6 to obtain melt A;

2) Under the protection of a mixed gas of CO ₂ and SF ₆ , heat the melt A to 740-750°C, then add Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles, and wait for the intermediate After the alloy is completely melted, remove the scum on the surface, stir evenly and heat up to 760-770°C, then cool down to 710-730°C, and then pour to obtain the cast alloy;

3) heat-treating the obtained as-cast alloy.

The particle size of the CaO particles is 3-5 μm.

Magnesium, aluminum, strontium, antimony, Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles are preheated before use. The temperature of the preheating treatment is 230-260° C., and the time is 1-3 hours.

When removing surface scum, the generated MgO can be removed at the same time.

Casting adopts the mold to carry out preheating treatment before pouring, and the temperature of preheating treatment is 300～350 ℃.

The heat treatment is to carry out solid solution treatment and aging treatment on the as-cast alloy in sequence.

The temperature of the solution treatment is 540-550° C., and the time is 5-8 hours. Solution treatment is carried out under the cover of magnesium oxide powder. This can prevent the occurrence of oxidative combustion. After solution treatment, it was quenched to room temperature with hot water. The temperature of the hot water is 80-90°C.

The temperature of the aging treatment is 230-250° C., and the time is 10-14 hours. After aging treatment, it can be cooled to room temperature by air cooling.

The flame-retardant magnesium alloy material of the present invention adopts Gd as the first component, and Gd has a very large solid solubility in the Mg solid solution, and the maximum solid solubility reaches 20.3%, and the solid solubility of Gd changes significantly with temperature, The solid solubility in Mg solid solution at 200°C is 3.8%. Gd can form a good aging precipitation strengthening effect in magnesium alloys. In order to ensure good aging precipitation strengthening and solid solution strengthening effects of the alloy, the addition of Gd is not low. 8%, and in order to reduce alloy cost, prevent alloy density from increasing too much and excessive embrittlement of alloy, so the Gd addition range of the present invention is 8.6～10.4%; Add 2.6～ 3.4% Nd and 1.6-2.4% Ce are used as the second component and the third component. The addition of Nd and Ce can significantly reduce the solid solubility of Gd in Mg, thereby increasing the aging precipitation strengthening effect of Gd; as a light The combination of Nd and Ce of rare earth elements and Gd of heavy rare earth elements can achieve a better aging strengthening effect. Sb is a magnesium alloy strengthening element and surface active element, which can refine the magnesium alloy grain and form a stable hexagonal structure Mg ₃ Sb ₂ compound. An appropriate amount of Sb can also improve the fluidity of the alloy liquid. Addition improves the normal and high temperature mechanical properties of the alloy, and effectively improves the high temperature creep resistance of the alloy. The addition of a small amount of Al in Mg-RE alloys can significantly refine the microstructure of the alloy, which is an important element to improve the heat resistance of magnesium alloys, and the addition of a small amount of CaO particles can improve the heat resistance and flame retardancy of magnesium alloys. The addition of Ca element in the flame-retardant magnesium alloy of the present invention is realized by adding CaO, the oxide of alloy element Ca, to the magnesium alloy liquid, and CaO is reduced to Ca through reduction reaction, and forms precipitated phases with Mg and other elements. The reduction reaction is:

CaO+Mg→Ca+MgO.

The addition of a small amount of CaO particles can improve the heat resistance and flame retardancy of the magnesium alloy on the one hand, and reduce the cost of the alloy on the other hand. Sr has a low density, and the addition of a small amount of Sr can significantly improve the room temperature and high temperature mechanical properties of flame-retardant magnesium alloys. In addition, it can increase the melting point of the solid solution of flame-retardant magnesium alloys and slow down the diffusion of elements in flame-retardant magnesium alloys. And significantly improve the flame retardant performance of flame retardant magnesium alloy, and the addition of a small amount of Sr has no obvious effect on the fluidity of the alloy.

Compared with the prior art, the flame-retardant magnesium alloy material of the present invention can significantly improve its overall performance through reasonable matching of different components, especially the mechanical properties and flame-retardant properties at room temperature and high temperature are significantly improved, and its resistance The tensile strength has an abnormal temperature effect, that is, as the stretching temperature increases, the tensile strength also increases.

The preparation method of the flame-retardant magnesium alloy material of the present invention comprehensively utilizes rare earth elements Gd, Nd and Ce, other elements Al, Sb and Sr, and adds a small amount of CaO particles to modify the alloy, and heat-treats the obtained cast alloy , will improve the comprehensive mechanical properties and flame retardancy of magnesium alloys effectively. Compared with the prior art, the smelting and heat treatment process of the flame-retardant magnesium alloy material of the present invention is simple, the microstructure of the magnesium alloy can be optimized through alloying, the strengthening phase can be formed to improve its mechanical properties, and the prepared magnesium alloy material has good mechanical properties and flame retardancy.

Detailed ways

The technical solution of the present invention will be further described below in combination with specific embodiments.

The pure magnesium, pure aluminum, pure strontium, pure antimony, Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles used in the preparation of flame-retardant magnesium alloy materials are commercially available. sell products. Wherein, the quality of Gd in the Mg-Gd master alloy is 25% of the Mg-Gd master alloy, the quality of Nd in the Mg-Nd master alloy is 30% of the Mg-Nd master alloy, and the quality of Ce in the Mg-Ce master alloy is 25% of Mg-Ce master alloy.

Example 1

The flame retardant magnesium alloy material of this embodiment is composed of the following components in mass percentage: Gd 8.6%, Nd 3.0%, Ce 2.2%, Al 1.3%, Sb 1.5%, Sr 0.33%, Ca 0.93%, and the balance is Mg and unavoidable impurities, the total mass fraction of impurity elements Fe, Cu and Ni is less than 0.2%.

The preparation method of the flame retardant magnesium alloy material of the present embodiment comprises the following steps:

1) Preheat the raw materials of pure magnesium, pure aluminum, pure strontium, pure antimony, Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles with a particle size of 3-5 μm. The preheating temperature is 240℃, preheating time is 2h;

2) melting the preheated pure magnesium, pure aluminum, pure strontium, and pure antimony under the protection of a mixed gas of _CO2 and _SF6 to obtain a melt A;

3) Under the protection of the mixed gas of _CO2 and _SF6 , add Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles with a particle size of 3-5 μm when the melt A is heated to 740 °C After the intermediate alloy is completely melted, remove the scum on the surface, stir evenly and heat up to 760°C, keep it warm for 15 minutes, then lower it to 720°C, keep it still for 13 minutes, and then pour the alloy liquid into the preheated metal mold to obtain the cast alloy ;The preheating temperature of the metal mold is 330°C;

4) The as-cast alloy is subjected to solution treatment at 540°C for 8 hours, then quenched with hot water at 80°C to room temperature, then subjected to aging treatment at 230°C for 14 hours, and air-cooled to room temperature. Carry out under cover to prevent oxidative combustion.

Example 2

The flame retardant magnesium alloy material of this embodiment is composed of the following components in mass percentage: Gd 9.0%, Nd 3.4%, Ce 1.6%, Al 1.5%, Sb 1.3%, Sr 0.38%, Ca 0.86%, and the balance is Mg and unavoidable impurities, the total mass fraction of impurity elements Fe, Cu and Ni is less than 0.2%.

The preparation method of the flame-retardant magnesium alloy material of this embodiment is the same as that of Embodiment 1.

Example 3

The flame retardant magnesium alloy material of the present embodiment is made up of the following components by mass percentage: Gd 10.0%, Nd2.8%, Ce 2.4%, Al 1.1%, Sb 1.6%, Sr 0.26%, Ca 1.0%, the balance is Mg and unavoidable impurities, the total mass fraction of impurity elements Fe, Cu and Ni is less than 0.2%.

The preparation method of the flame-retardant magnesium alloy material of this embodiment is the same as that of Embodiment 1.

Example 4

The flame retardant magnesium alloy material of the present embodiment is made up of the following components by mass percentage: Gd 10.4%, Nd2.6%, Ce 2.9%, Al 1.2%, Sb 1.1%, Sr 0.30%, Ca 0.78%, the balance is Mg and unavoidable impurities, the total mass fraction of impurity elements Fe, Cu and Ni is less than 0.2%.

The preparation method of the flame-retardant magnesium alloy material of this embodiment is the same as that of Embodiment 1.

Example 5

The flame retardant magnesium alloy material of this embodiment is composed of the following components in mass percentage: Gd 9.4%, Nd 3.2%, Ce 2.0%, Al 1.25%, Sb 1.4%, Sr 0.35%, Ca 0.88%, and the balance is Mg and unavoidable impurities, the total mass fraction of impurity elements Fe, Cu and Ni is less than 0.2%.

The preparation method of the flame retardant magnesium alloy material of the present embodiment comprises the following steps:

1) Preheat the raw materials of pure magnesium, pure aluminum, pure strontium, pure antimony, Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles with a particle size of 3-5 μm. The preheating temperature is 260℃, preheating time is 1h;

2) melting the preheated pure magnesium, pure aluminum, pure strontium, and pure antimony under the protection of a mixed gas of _CO2 and _SF6 to obtain a melt A;

3) Under the protection of the mixed gas of _CO2 and _SF6 , add Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles with a particle size of 3-5 μm when the melt A is heated to 750 °C After the intermediate alloy is completely melted, remove the scum on the surface, stir evenly and heat up to 765°C, keep it warm for 13 minutes, then lower it to 710°C, keep it still for 15 minutes, and then pour the alloy liquid into the preheated metal mold to obtain the cast alloy ;The preheating temperature of the metal mold is 350°C;

4) The as-cast alloy is subjected to solution treatment at 550°C for 5 hours, then quenched with hot water at 85°C to room temperature, then subjected to aging treatment at 240°C for 12 hours, and air-cooled to room temperature to obtain; solution treatment is covered with magnesium oxide powder to prevent oxidative combustion.

Example 6

The flame retardant magnesium alloy material of this embodiment is composed of the following components in mass percentage: Gd 9.7%, Nd 3.1%, Ce 2.6%, Al 1.4%, Sb 1.2%, Sr 0.28%, Ca 0.97%, and the balance is Mg and unavoidable impurities, the total mass fraction of impurity elements Fe, Cu and Ni is less than 0.2%.

The preparation method of the flame retardant magnesium alloy material of the present embodiment comprises the following steps:

1) Preheat the raw materials of pure magnesium, pure aluminum, pure strontium, pure antimony, Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles with a particle size of 3-5 μm. The preheating temperature is 230℃, preheating time is 3h;

2) melting the preheated pure magnesium, pure aluminum, pure strontium, and pure antimony under the protection of a mixed gas of _CO2 and _SF6 to obtain a melt A;

3) Under the protection of the mixed gas of _CO2 and _SF6 , add Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles with a particle size of 3-5 μm when the melt A is heated to 740 °C After the intermediate alloy is completely melted, remove the scum on the surface, stir evenly and heat up to 770°C, keep it warm for 10 minutes, then lower it to 730°C, keep it still for 10 minutes, and then pour the alloy liquid into the preheated metal mold to obtain the cast alloy ;The preheating temperature of the metal mold is 300°C;

4) The as-cast alloy is subjected to solution treatment at 545°C for 7 hours, then quenched with hot water at 90°C to room temperature, then subjected to aging treatment at 250°C for 10 hours, and air-cooled to room temperature. Carry out under cover to prevent oxidative combustion.

Experimental example

The mechanical properties and ignition points of the flame-retardant magnesium alloy materials in Examples 1-6 were tested respectively, and the test results are shown in Table 1. It can be seen from the data in the table that the flame-retardant magnesium alloy materials of Examples 1-6 have high tensile strength and yield strength at room temperature and 250°C, and their tensile strength has an abnormal temperature effect, that is, with As the stretching temperature increases, the tensile strength also increases. The results of the ignition point test show that the alloy has excellent flame retardancy.

The mechanical properties and flame retardant performance of the flame retardant magnesium alloy material of table 1 embodiment 1～6

Claims (10)

1. A flame-retardant magnesium alloy material, characterized in that: it consists of the following components in mass percentage: Gd 8.6-10.4%, Nd 2.6-3.4%, Ce 1.6-2.9%, Al 1.1-1.5%, Sb 1.1- 1.6%, Sr 0.26-0.38%, Ca 0.78-1.0%, and the balance is Mg and unavoidable impurities. 2. The flame retardant magnesium alloy material according to claim 1, characterized in that the sum of the mass percentages of the impurity elements Fe, Cu and Ni is less than 0.2%. 3. A preparation method of flame-retardant magnesium alloy material as claimed in claim 1, characterized in that: comprising the following steps: 1) melting raw materials magnesium, aluminum, strontium and antimony under the protection of a mixed gas of _CO2 and _SF6 to obtain melt A; 2) Under the protection of a mixed gas of CO ₂ and SF ₆ , heat the melt A to 740-750°C, then add Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particles, and wait for the intermediate After the alloy is completely melted, remove the scum on the surface, stir evenly and heat up to 760-770°C, then cool down to 710-730°C, and then pour to obtain the cast alloy; 3) heat-treating the obtained as-cast alloy. 4 . The method for preparing flame-retardant magnesium alloy material according to claim 3 , characterized in that: the particle diameter of the CaO particles is 3-5 μm. 5. the preparation method of flame-retardant magnesium alloy material according to claim 3 is characterized in that: magnesium, aluminum, strontium, antimony, Mg-Gd master alloy, Mg-Nd master alloy, Mg-Ce master alloy and CaO particle Preheat before use. 6 . The preparation method of flame-retardant magnesium alloy material according to claim 5 , characterized in that: the temperature of the preheating treatment is 230-260° C. and the time is 1-3 hours. 7 . The preparation method of the flame retardant magnesium alloy material according to claim 3 , characterized in that the casting adopts a mold to perform preheating treatment before casting, and the temperature of the preheating treatment is 300-350° C. 7 . 8 . The method for preparing flame retardant magnesium alloy material according to claim 3 , characterized in that: the heat treatment is sequentially performing solution treatment and aging treatment on the as-cast alloy. 9 . The method for preparing a flame-retardant magnesium alloy material according to claim 8 , characterized in that: the temperature of the solution treatment is 540-550° C. and the time is 5-8 hours. 10 . The method for preparing a flame-retardant magnesium alloy material according to claim 8 , characterized in that: the temperature of the aging treatment is 230-250° C. and the time is 10-14 hours. 11 .