阅读说明：本技术 一种合金快速热压成型方法 (Rapid hot-press forming method for alloy ) 是由 张文兴 许军锋 王鑫 王喜锋 李高宏 于 2021-07-09 设计创作，主要内容包括：本发明公开了一种合金快速热压成型方法,合金包括一种主要元素与至少一种合金元素,快速热压成型方法包括以下内容：S1、混粉：将主要元素的粉末与低熔点粉末混合,得到混合粉末；若合金元素的熔点低于主要元素粉末的熔点,则低熔点粉末为各种单一的合金元素粉末；当合金元素的熔点等于或高于主要元素粉末的熔点,则低熔点粉末为中间合金粉末,中间合金粉末由主要元素和至少一种的合金元素组成；S2、冷压：对经S1得到的混合粉末进行冷压成形得到冷压坯体,冷压坯体的致密度≤85％；S3、热压烧结制得合金。解决了现有金属基复合材料的粉末冶金制备方法或合金粉末冶金制备方法制得的产品生产效率低、生产成本高的问题。(The invention discloses a rapid hot-press forming method of an alloy, wherein the alloy comprises a main element and at least one alloy element, and the rapid hot-press forming method comprises the following steps: s1, mixing powder: mixing the powder of the main element with the powder with low melting point to obtain mixed powder; if the melting point of the alloying element is lower than that of the main element powder, the low-melting-point powder is various single alloying element powders; when the melting point of the alloying element is equal to or higher than that of the main element powder, the low-melting-point powder is master alloy powder which consists of the main element and at least one alloying element; s2, cold pressing: carrying out cold pressing forming on the mixed powder obtained in the step S1 to obtain a cold-pressed blank, wherein the density of the cold-pressed blank is less than or equal to 85%; and S3, hot-pressing and sintering to obtain the alloy. Solves the problems of low production efficiency and high production cost of products prepared by the existing powder metallurgy preparation method or alloy powder metallurgy preparation method of the metal-based composite material.)

1. A rapid hot press forming method for an alloy, which is characterized in that the alloy comprises a main element and at least one alloy element, and the rapid hot press forming method comprises the following steps:

s1, mixing powder:

mixing the powder of the main element with the powder with low melting point to obtain mixed powder; the melting point of the low-melting-point powder is more than 30 ℃ lower than that of the main element;

if the melting point of the alloying element is lower than that of the main element powder, the low-melting-point powder is various single alloying element powders;

when the melting point of the alloying element is equal to or higher than the melting point of the main element powder, the low-melting-point powder is master alloy powder, and the master alloy powder consists of the main element and at least one alloying element;

s2, cold pressing:

carrying out cold press forming on the mixed powder obtained by the step S1 to obtain a cold-pressed blank, wherein the density of the cold-pressed blank is less than or equal to 85%;

s3, hot-pressing and sintering:

s3.1, hot pressing earlier stage: putting the cold-pressed blank into a hot-pressing die capable of being rapidly heated, and heating the cold-pressed blank to a preset hot-pressing temperature within 3-5 minutes by using rapid heating equipment, wherein the hot-pressing temperature is 10-100 ℃ higher than the melting point of the low-melting-point powder, and the applied pressure is 3-10 MPa;

s3.2, hot pressing middle stage: after the temperature of the cold-pressed blank body reaches the preset hot-pressing temperature, reducing the applied pressure to 0.1-0.5MPa, and keeping for 5 minutes;

s3.3, hot pressing later stage: and increasing the applied pressure to 5-20MPa, keeping the temperature for 10-20 minutes, stopping heating, unloading when the temperature is reduced to be lower than the melting point of the low-melting-point powder by 100 ℃, and demoulding to obtain the alloy.

2. The rapid hot press molding method of alloy according to claim 1, wherein when the Al10Mg alloy is prepared, in the step S1, pure aluminum powder and master alloy powder are mixed to obtain mixed powder, and the master alloy powder is Al50Mg or Al35 Mg; wherein, Al: the mass ratio of Al50Mg is 4: 1, Al: the mass ratio of Al35Mg was 5: 2.

3. The rapid hot press molding method for alloy according to claim 2, characterized in that the mixed powder is cold pressed to obtain a cold pressed blank, the cold pressing pressure is 100MPa, and the blank is demolded after holding pressure for 3 minutes;

putting the cold-pressed green body into a hot-pressing die, applying 5MPa pre-pressurizing force, and heating the cold-pressed green body to the preset temperature of 460 ℃ by using high frequency for 5 minutes; then reducing the pressure to 0.1MPa, and keeping for 5 minutes; gradually increasing the pressure to 20MPa, keeping the pressure for 15 minutes, stopping heating, and taking out the cold-pressed blank to obtain a hot-pressed blank when the temperature of the cold-pressed blank is reduced to 350 ℃; and carrying out homogenization treatment or heat treatment on the hot pressed compact to obtain the alloy Al10 Mg.

4. The method for rapid hot press forming of alloy as claimed in claim 1, wherein in step S1, pure aluminum powder and Al33Cu powder are mixed to obtain mixed powder, and the ratio of Al: the mass ratio of Al33Cu was 5: 1.

After the mixed powder is processed through the steps S2-S3, Al5Cu alloy is prepared;

wherein, the predetermined hot pressing temperature before the hot pressing in step S3 is 600-640 ℃.

Technical Field

The invention belongs to the technical field of powder metallurgy materials, and particularly relates to a rapid hot-press forming method of an alloy.

Background

With the continuous development of modern science and technology, various novel materials, especially composite materials, are rapidly developed, for example, metal matrix composite materials, and composite materials also gradually become indispensable novel materials in the engineering field. There are many methods for preparing metal matrix composite materials, such as stirring casting method, vacuum or pressure infiltration method, spray deposition method, powder metallurgy method, etc., wherein the powder metallurgy method is one of the best methods for preparing new materials recognized in the research field. However, the methods adopted in the production of metal-based composite materials at home and abroad, particularly the methods adopted in mass products, are not used much in the powder metallurgy method, and the reasons are that the traditional powder metallurgy cold press molding pressure is large, the hot press time is long, and the like, so that the poor results that the product size cannot be too large, the production efficiency is low, and the like are caused, and the application of the powder metallurgy method in the field of the production of the metal-based composite materials is greatly limited. The reasons for this are in addition to the powder metallurgy process factors, the choice of the composite base metal is the root cause.

Disclosure of Invention

The invention aims to provide a rapid hot-press forming method of an alloy, which aims to solve the problems of low production efficiency and high production cost of products prepared by the existing powder metallurgy preparation method or alloy powder metallurgy preparation method of metal matrix composites.

The invention adopts the following technical scheme: a method for quickly hot-press forming alloy, which comprises a main element and at least one alloy element, comprises the following steps:

s1, mixing powder:

mixing the powder of the main element with the powder with low melting point to obtain mixed powder; the melting point of the low-melting-point powder is more than 30 ℃ lower than that of the main element;

if the melting point of the alloying element is lower than that of the main element powder, the low-melting-point powder is various single alloying element powders;

when the melting point of the alloying element is equal to or higher than that of the main element powder, the low-melting-point powder is master alloy powder which consists of the main element and at least one alloying element;

s2, cold pressing:

carrying out cold pressing forming on the mixed powder obtained in the step S1 to obtain a cold-pressed blank, wherein the density of the cold-pressed blank is less than or equal to 85%;

s3, hot-pressing and sintering:

s3.1, hot pressing earlier stage: putting the cold-pressed blank into a hot-pressing die capable of being rapidly heated, and heating the cold-pressed blank to a preset hot-pressing temperature within 3-5 minutes by using rapid heating equipment, wherein the hot-pressing temperature is 10-100 ℃ higher than the melting point of the low-melting-point powder, and the applied pressure is 3-10 MPa;

s3.2, hot pressing middle stage: after the temperature of the cold-pressed blank body reaches the preset hot-pressing temperature, reducing the applied pressure to 0.1-0.5MPa, and keeping for 5 minutes;

s3.3, hot pressing later stage: and increasing the applied pressure to 5-20MPa, keeping the temperature for 10-20 minutes, stopping heating, unloading when the temperature is reduced to be lower than the melting point of the low-melting-point powder by 100 ℃, and demoulding to obtain the alloy.

Further, when the Al10Mg alloy is prepared, in step S1, pure aluminum powder and master alloy powder are mixed to obtain mixed powder, the master alloy powder is Al50Mg or Al35 Mg; wherein, Al: the mass ratio of Al50Mg is 4: 1, Al: the mass ratio of Al35Mg was 5: 2.

Further, carrying out cold pressing on the mixed powder to obtain a cold-pressed blank, wherein the cold-pressing pressure is 100MPa, and demoulding is carried out after keeping the pressure for 3 minutes;

putting the cold-pressed green body into a hot-pressing die, applying 5MPa pre-pressurizing force, and heating the cold-pressed green body to the preset temperature of 460 ℃ by high frequency for 5 minutes; then reducing the pressure to 0.1MPa, and keeping for 5 minutes; gradually increasing the pressure to 20MPa, keeping the pressure for 15 minutes, stopping heating, and taking out the cold-pressed blank when the temperature of the cold-pressed blank is reduced to 350 ℃ to obtain a hot-pressed blank; and carrying out homogenization treatment or heat treatment on the hot-pressed blank to obtain the alloy Al10 Mg.

Further, in step S1, pure aluminum powder and Al33Cu powder are mixed to obtain a mixed powder, where Al: the mass ratio of Al33Cu was 5: 1.

After the mixed powder is processed through the steps S2-S3, Al5Cu alloy is prepared;

wherein, the predetermined hot pressing temperature before the hot pressing in step S3 is 600-640 ℃.

The invention has the beneficial effects that: according to the invention, a low-melting-point formula is added into powder raw materials, a rapid heating process (the temperature is raised to a hot pressing temperature and is generally only 3-5 minutes, the time required by conventional heating is generally more than 30 minutes) is adopted, the principle of the conventional powder metallurgy process is broken through, the highest pressure required during hot pressing is 20MPa (the conventional hot pressing is generally 100-200MPa), the required time is generally 15-30 minutes (the conventional hot pressing is generally 1-2 hours), the process flow of conventional powder metallurgy sintering and densification (hot pressing/hot extrusion) is simplified into rapid hot pressing, and the density of the obtained product can reach or exceed 98% through one-step low-pressure hot pressing. The powder metallurgy alloy developed by the technology can greatly enrich the matrix alloy of the powder metallurgy metal-based composite material, so that different matrix alloys can be selected according to the actual working condition requirement to obtain the optimized performance of the metal-based composite material, thereby expanding the application range of the metal-based composite material and making contribution to improving the international competitiveness of products in China.

Drawings

FIG. 1 is a microstructure photograph of an Al10Mg alloy at a low magnification, obtained in example S3 of the present invention;

FIG. 2 is a high magnification microstructure picture of Al10Mg alloy obtained in example S3 of the present invention;

fig. 3 is a comparison graph of the technical process and the compactness of the alloy obtained in the comparative example and the example 1.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention provides a rapid hot-press forming method of an alloy, wherein the alloy comprises a main element and at least one alloy element, and the rapid hot-press forming method comprises the following steps:

s1, mixing powder:

mixing the powder of the main element with the powder with low melting point to obtain mixed powder; the melting point of the low-melting powder is 30 ℃ or higher lower than that of the main element.

The mixing ratio of the main element powder and the low-melting-point powder is determined according to the alloy components. For example, an Al10Mg alloy is prepared from pure aluminum powder and Al50Mg powder, and assuming that the Al50Mg content is x, the pure aluminum powder is 1-x, 50% x is 10%, and x is calculated to be 0.2, so that the pure aluminum powder: al50Mg ═ 4: 1.

if the melting point of the alloying element is lower than that of the main element powder, the low-melting-point powder is various single alloying element powders;

if the melting point of the alloy element is equal to or higher than that of the main element powder, the low-melting-point powder is master alloy powder, the master alloy powder consists of the main element and at least one alloy element, and the content of the alloy element in the master alloy powder is higher than that of the alloy element in the alloy;

s2, cold pressing:

carrying out cold pressing forming on the mixed powder obtained in the step S1 to obtain a cold-pressed blank; the density of the cold-pressed green body is less than or equal to 85 percent;

s3, hot-pressing and sintering:

s3.1, hot pressing earlier stage: putting the cold-pressed blank into a hot-pressing die capable of being rapidly heated, and heating the cold-pressed blank to a preset hot-pressing temperature within 3-5 minutes by using rapid heating equipment, wherein the hot-pressing temperature is 10-100 ℃ higher than the melting point of the low-melting-point powder, and the applied pressure is 3-10 MPa;

s3.2, hot pressing middle stage: after the temperature of the cold-pressed blank body reaches the preset hot-pressing temperature, reducing the applied pressure to 0.1-0.5MPa, and keeping for 5 minutes;

s3.3, hot pressing later stage: increasing the applied pressure to 5-20MPa, keeping the temperature for 10-20 minutes, stopping heating, and unloading and demoulding when the temperature is reduced to 100 ℃ lower than the melting point of the low-melting-point powder; the hot-pressed billet after the mold release may be subjected to homogenization treatment or heat treatment as necessary to obtain an alloy.

In some embodiments, when preparing the Al10Mg alloy, in step S1, pure aluminum powder and master alloy powder are mixed to obtain mixed powder, the master alloy powder being Al50Mg or Al35 Mg; wherein, Al: the mass ratio of Al50Mg is 4: 1, Al: the mass ratio of Al35Mg was 5: 2.

The alloy Al10Mg can be prepared from pure aluminum powder and Al50Mg, or from pure aluminum powder and Al35Mg, the mixed powder of the two formulas is the same in the subsequent hot-press forming process, and only the mixture ratio of the raw materials needs to be adjusted to be different.

The aluminum silicon alloy can be prepared by the method, such as preparing an alloy Al7 Si: pure aluminum powder and Al12Si powder were mixed at a ratio of 5: 7, cold pressing, hot pressing at 590-640 ℃, and maintaining the pressure for 15-30 minutes to obtain powder metallurgy Al7Si with the component close to that of the cast aluminum 101; or 1.5 percent of Al35Mg can be added into the raw materials without changing the forming process, powder metallurgy Al7SiMg with the same composition as the cast aluminum 101 can be obtained, and the subsequent heat treatment can be carried out according to the process of the cast aluminum 101.

In some embodiments, the mixed powder is subjected to cold pressing to obtain a cold-pressed green body, the cold-pressing pressure is 100MPa, and the green body is demoulded after being kept for 3 minutes;

putting the cold-pressed green body into a hot-pressing die, applying 5MPa pre-pressurizing force, and heating the cold-pressed green body to the preset temperature of 460 ℃ by high frequency for 5 minutes; then reducing the pressure to 0.1MPa, and keeping for 5 minutes; gradually increasing the pressure to 20MPa, keeping the pressure for 15 minutes, stopping heating, and taking out the cold-pressed blank when the temperature of the cold-pressed blank is reduced to 350 ℃ to obtain a hot-pressed blank;

and carrying out homogenization treatment or heat treatment on the hot-pressed blank to obtain the alloy Al10 Mg.

In some embodiments, in step S1, the pure aluminum powder and the Al33Cu powder are mixed to obtain a mixed powder, where Al: the mass ratio of Al33Cu is 5: 1;

after the mixed powder is processed through the steps S2-S3, Al5Cu alloy is prepared;

wherein, the predetermined hot pressing temperature before the hot pressing in step S3 is 600-640 ℃.

Example (b):

s1, mixing pure aluminum powder and master alloy powder to obtain mixed powder, wherein the master alloy powder is Al50Mg or Al35 Mg; wherein, Al: the mass ratio of Al50Mg is 4: 1, Al: the mass ratio of Al35Mg is 5: 2;

s2, cold-pressing the mixed powder to obtain a cold-pressed blank, and cold-pressing the cold-pressed blank in a steel mould, wherein the size of the cold-pressed blank is phi 20 x 10mm, the cold-pressing pressure is 100MPa, and demoulding is carried out after the pressure is maintained for 3 minutes;

s3, placing the cold-pressed green body into a hot-pressing die, applying 5MPa of pre-pressing force, and heating the cold-pressed green body to the preset temperature of 460 ℃ by high frequency for 5 minutes; then reducing the pressure to 0.1MPa, and keeping for 5 minutes; and gradually increasing the pressure to 20MPa, keeping the pressure for 15 minutes, stopping heating, and taking out the cold-pressed blank when the temperature of the cold-pressed blank is reduced to 350 ℃ to obtain the hot-pressed blank. As shown in fig. 1 and 2, the tissue after heat pressing is dense and has no obvious holes.

And S4, carrying out homogenization treatment or heat treatment on the hot-pressed blank to obtain alloy Al10 Mg.

The hot green compact was measured to have a density of 97.8% and a hardness of 72.8 HBW.

Comparative example:

s1, mixing pure aluminum powder and Al50Mg in a mass ratio of 4: 1, mixing;

s2, cold-pressing the mixed powder to obtain a cold-pressed blank, and cold-pressing the cold-pressed blank in a steel mould, wherein the size of the cold-pressed blank is phi 20 x 10mm, the cold-pressing pressure is 400MPa, and demoulding is carried out after the pressure is maintained for 3 minutes;

and S3, putting the cold-pressed blank into a hot-pressing die, heating the blank by using a traditional resistance furnace for 30 minutes, raising the temperature to 460 ℃, applying 200MPa pressure, maintaining the pressure for 2 hours, cooling and demoulding to obtain the alloy Al10 Mg.

The hot green compact was measured to have a density of 98.2% and a hardness of 73 HBW.

According to the comparison graph of the main process parameters and the density of the hot-pressed blank of the embodiment of the invention and the comparative example in fig. 3, it can be seen that under the condition of quite large forming effect, the technical process requirement of the embodiment of the invention is lower, the process time is shorter, and the industrial production is more facilitated. According to the invention, a low-melting-point formula is added into powder raw materials, a rapid heating process (the temperature is raised to a hot pressing temperature and is generally only 3-5 minutes, the time required by conventional heating is generally more than 30 minutes) is adopted, the principle of the conventional powder metallurgy process is broken through, the highest pressure required during hot pressing is 20MPa (the conventional hot pressing is generally 100-200MPa), the required time is generally 15-30 minutes (the conventional hot pressing is generally 1-2 hours), the process flow of conventional powder metallurgy sintering and densification (hot pressing/hot extrusion) is simplified into rapid hot pressing, and the density of the obtained product can reach or exceed 98% through one-step low-pressure hot pressing.

The alloy rapid hot-press forming method has the following advantages: the process is simplified, and a main sintering process is reduced; the hot pressing pressure is low, is 1/10 of the conventional hot pressing and even lower, and 10 or more products can be produced by single hot pressing under the same pressure equipment through the design of a die; the hot pressing time is short; the heat pressing die is adaptive to hot pressing, the cold pressing pressure is reduced to 1/4-1/2 of conventional powder metallurgy, and the production efficiency can be improved by 2-4 times through die design. The powder metallurgy alloy produced by the technology can greatly reduce the die loss and prolong the service life of the die due to low cold pressing and hot pressing pressure, and can also reduce the die processing cost by selecting proper materials and processing technology, namely, the die processing and maintenance cost in large-scale production is reduced, so that the product price is reduced, and the product competitiveness is improved. The powder metallurgy alloy developed by the technology can greatly enrich the matrix alloy of the powder metallurgy metal-based composite material, so that different matrix alloys can be selected according to the actual working condition requirement to obtain the optimized performance of the metal-based composite material, thereby expanding the application range of the metal-based composite material and making contribution to improving the international competitiveness of products in China.