CN104152775B - A kind of long-periodic structure strengthens magnesium alloy semisolid slurry and its preparation method - Google Patents

Abstract

The invention discloses a long-period structure reinforced magnesium alloy semi-solid slurry in the technical field of metal materials and a preparation method thereof. The composition of the semi-solid slurry is: 86.7% magnesium, 2.2% nickel, 5.8% gadolinium, 5.3% neodymium. The preparation of the semi-solid slurry is to mix Mg, Ni, Gd and Nd according to the required element composition ratio and melt under the protection of argon to obtain the Mg-Ni-Gd-Nd master alloy ingot; put the master alloy ingot into The stainless steel crucible is reheated and kept warm, and then the crucible is placed in a pulsed magnetic field to solidify, and finally the Mg-Ni-Gd-Nd semi-solid slurry is obtained. The semi-solid slurry belongs to high-strength and high-toughness magnesium alloy, and is suitable for preparing parts with complex shapes; the preparation method has the advantages of easy control over the process, relatively good component control, and no component pollution.

Description

A long-period structure reinforced magnesium alloy semi-solid slurry and its preparation method

technical field

The invention relates to an alloy semi-solid slurry in the technical field of metal materials and a preparation method thereof, in particular to a long-period structurally reinforced magnesium alloy semi-solid slurry and a preparation method thereof.

Background technique

Magnesium alloy is currently the lightest metal structural material in practical engineering applications. It has the characteristics of low density, high specific strength and specific stiffness, excellent casting, shock absorption, machinability and good dimensional stability, making it ideal for lightweight, It plays a significant role in reducing energy consumption and reducing environmental pollution, and is being increasingly widely used in industrial fields such as automobiles, national defense, aerospace, electronics, and machinery, as well as household goods and sports equipment. However, there are basic problems such as low strength, toughness and poor plasticity in the research and application of magnesium alloys. Finding effective strengthening methods is a key basic problem in the research and development of high-strength magnesium alloys. Designing the composition of magnesium alloys and introducing effective strengthening phases are important means to develop high-strength magnesium alloys. In the past ten years, a new long-period structurally strengthened magnesium alloy has attracted people's attention. The long-period structure-strengthened Mg-Y-Zn magnesium alloy prepared by the rapid solidification powder metallurgy method has a tensile yield strength of up to 610MPa at room temperature, and an elongation rate of more than 5%; at 423K, the yield strength also reaches 510MPa. The highest strength magnesium alloy ever prepared. With the deepening of research, researchers generally believe that magnesium alloys with long-term structural reinforcement can become a new generation of high-strength and high-toughness magnesium alloys.

Noto Kawamura's invention patent "High-strength and high-toughness magnesium alloy and its preparation method" (CN10145417B, May 25, 2011) proposed that Mg-Ni-RE magnesium alloy is a high-strength and high-toughness magnesium alloy with long-term structural reinforcement, and Two types of material processing methods for the magnesium alloy are proposed, one is rapid solidification, and the other is plastic processing methods. However, these two types of material processing methods cannot obtain products with complex shapes and large volumes. Recently, a new material processing technology has been paid attention to, which is called semi-solid forming technology. The basic principle of semi-solid forming technology is: use a certain method to obtain semi-solid slurry (blank) material with non-dendritic structure, and solidify and form it in different shapes of cavities by pressing. This method can obtain products with complex shapes and large volumes. At the same time, it can reduce casting defects in the formed parts and improve the mechanical properties of the parts. It is a near-net shape technology that can achieve less and no margin processing. Therefore, the application of semi-solid forming technology to the processing of long-period structure-reinforced magnesium alloys can further expand the application range of high-strength and high-toughness magnesium alloys and meet the increasingly stringent requirements for aerospace materials.

The key to semi-solid processing technology is how to make ideal semi-solid metal paste. That is to say, the key to realize the semi-solid processing of long-period structure-reinforced magnesium alloy is to prepare the semi-solid slurry of long-period structure-reinforced magnesium alloy. After searching the literature, there is no report on the study of semi-solid slurry of Mg-Ni-RE magnesium alloy reinforced with long-period structure.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the existing research, provide a long-period structure reinforced Mg-Ni-Gd-Nd magnesium alloy semi-solid slurry and its preparation method, and solve the key problem of semi-solid formation technology - semi-solid slurry The preparation provides technical support for the semi-solid forming of high-strength and high-toughness magnesium alloys.

The present invention is achieved through the following technical solutions:

The semi-solid slurry involved in the present invention is a semi-solid slurry of Mg-Ni-Gd-Nd alloy reinforced by long-period structure, which comprises the following components (by weight): 86.7% magnesium, 2.2% Nickel, 5.8% gadolinium, 5.3% neodymium.

The preparation method of the magnesium alloy semi-solid slurry involved in the present invention comprises the following steps:

(1) According to the alloy composition of 86.7% magnesium, 2.2% nickel, 5.8% gadolinium, and 5.3% neodymium, prepare magnesium, nickel and rare earth gadolinium and neodymium raw materials; the above-mentioned magnesium, nickel, gadolinium, and neodymium raw materials have a purity of more than 99.9% .

(2) Put the raw materials in step (1) into a graphite crucible, and use a high-frequency induction heating furnace for melting. The high-frequency induction heating current is gradually increased from 150 amperes to 400 amperes, so as to realize slow heating of the raw materials until they are melted. A master alloy ingot is obtained.

The smelting process was maintained at 45 minutes: the current was 150 amperes for the first 5 minutes, the current was 250 amperes for the next 10 minutes, and the current was 400 amperes for the last 30 minutes.

The smelting and melting are carried out in a sealed chamber, using a graphite crucible, the atmosphere is a pure argon atmosphere with a purity greater than 99.99%, and the atmosphere pressure is 1 atmosphere.

(3) Put the master alloy ingot obtained in step (2) into a stainless steel crucible, reheat to 600°C in a resistance furnace, and keep it warm for 20 minutes.

The heating process is carried out under the protection of argon, and the atmosphere is a pure argon atmosphere with an argon purity greater than 99.99%.

(4) Place the stainless steel crucible containing the master alloy reheated in step (3) in a pulsed magnetic field, and the alloy is solidified under the action of the pulsed magnetic field to obtain a magnesium alloy semi-solid slurry.

The intensity of the pulsed magnetic field is controlled by voltage, the voltage used is 350V; the frequency of the pulsed magnetic field is 20 Hz; the action time of the pulsed magnetic field is 5 minutes.

The magnesium alloy semi-solid slurry provided by the invention is a magnesium alloy semi-solid slurry with long-period structural reinforcement, which belongs to high-strength and high-toughness magnesium alloy; the preparation method of the semi-solid slurry provided by the invention is easy to control the process, and the composition control is relatively good , no component pollution, suitable for semi-solid forming technology to prepare parts with complex shapes.

Description of drawings

Fig. 1 is the XRD diffraction spectrum of embodiment;

Fig. 2 is a metallographic structure diagram of the embodiment.

detailed description

The embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings: this embodiment is implemented on the premise of the technical solution of the present invention, and provides detailed implementation methods and specific operating procedures.

Example: Mg-Gd-Nd-Ni magnesium alloy semi-solid slurry, the slurry contains the following components (by weight percentage): 86.7% magnesium, 2.2% nickel, 5.8% gadolinium, 5.3% neodymium.

In the first step, according to the alloy composition of 86.7% magnesium, 2.2% nickel, 5.8% gadolinium, and 5.3% neodymium, magnesium, nickel, and rare earth gadolinium and neodymium raw materials are prepared. The purity of the magnesium, nickel, gadolinium, and neodymium raw materials used is above 99.9%. , Nickel, gadolinium, and neodymium are small particles, the size of which is less than 1mm.

In the second step, put the raw material of the first step into a graphite crucible and melt it in a high-frequency induction heating furnace. Realize the slow heating of raw materials until they are melted to obtain master alloy ingots.

In the third step, the above-mentioned master alloy ingot was put into a stainless steel crucible, reheated to 600° C. in a resistance furnace, and kept warm for 20 minutes.

The fourth step is to place the stainless steel crucible with the master alloy reheated in the third step in a pulsed magnetic field, the voltage of the pulsed magnetic field is 350V, the frequency is 20 Hz, and the action time is 5 minutes. The alloy is solidified under the action of the pulsed magnetic field. A magnesium alloy semi-solid slurry is obtained.

It can be seen from the XRD diffraction spectrum of the example in Fig. 1 that the example is composed of a-Mg phase and long-period structural phase X-phase, that is to say, a magnesium alloy reinforced by a long-period structure. Figure 2 shows that the semi-solid slurry is composed of white a-Mg phase and gray long-period structure phase.

Claims (7)

1. A long-period structure reinforced magnesium alloy semi-solid slurry, the semi-solid slurry is a Mg-Ni-Gd-Nd alloy, and its composition (percentage by weight) is 86.7% magnesium, 2.2% nickel, 5.8% gadolinium, 5.3% neodymium. 2. A method for preparing a long-period structure reinforced magnesium alloy semi-solid slurry, comprising the steps of: The first step is to prepare magnesium, nickel, rare earth gadolinium and neodymium raw materials according to the alloy composition of 86.7% magnesium, 2.2% nickel, 5.8% gadolinium, and 5.3% neodymium; The second step is to put the raw materials of the first step into the graphite crucible and melt them in a high-frequency induction heating furnace. The high-frequency induction heating current is gradually increased from 150 amperes to 400 amperes to realize the slow heating of the raw materials until they are melted, and the parent material is obtained. alloy ingot; The third step is to put the master alloy ingot obtained in the second step into a stainless steel crucible, reheat it to 600°C in a resistance furnace, and keep it warm for 20 minutes; In the fourth step, the stainless steel crucible filled with the master alloy reheated in the third step is placed in a pulsed magnetic field, and the alloy is solidified under the action of the pulsed magnetic field to obtain a magnesium alloy semi-solid slurry. 3. The method for preparing a long-period structurally reinforced magnesium alloy semi-solid slurry according to claim 2, in the first step, the purity of the magnesium, nickel, gadolinium, and neodymium raw materials is above 99.9%. 4. the preparation method of the long-period structure reinforced magnesium alloy semi-solid slurry according to claim 2, in the second step, the smelting process time is 45 minutes: the electric current is 150 amperes in the first 5 minutes, and the electric current in the next 10 minutes is 250 amps and 400 amps for the last 30 minutes. 5. The preparation method of the long-period structure reinforced magnesium alloy semi-solid slurry according to claim 2, in the second step, the smelting and melting are carried out in a sealed chamber, using a graphite crucible, and the atmosphere has a purity greater than 99.99% The pure argon atmosphere, the atmosphere pressure is 1 atmosphere. 6. The preparation method of the long period structure reinforced magnesium alloy semi-solid slurry according to claim 2, in the third step, the heating process is carried out under the protection of argon, and the atmosphere is a pure argon atmosphere with an argon purity greater than 99.99% , the atmospheric pressure is 1 atmosphere. 7. The preparation method of the long-period structure reinforced magnesium alloy semi-solid slurry according to claim 2, in the fourth step, the solidification process is carried out under a pulsed magnetic field, and the intensity of the pulsed magnetic field is controlled by voltage, and the voltage used is is 350V; the frequency of the pulsed magnetic field is 20 Hz; the action time of the pulsed magnetic field is 5 minutes.