We have all learned about the methods of amorphous welding before, and now we have researched many methods of preparing amorphous welding alloys. These methods are based on the different states of amorphous alloys. Now these methods can be roughly summed up. There are eight types. Each method has its own advantages and scope of application, please see the detailed introduction below.

1. Direct condensation method

The direct condensation method firstly melts and mixes the master alloy evenly, and then selects the method of purification and rapid cooling to make the alloy liquid quenched in a short time. To a large extent, it will be constrained by the ability of the alloy to form amorphous. The direct condensation methods mainly include: water quenching method, copper mold casting method, high pressure die casting method, suction casting method, die casting method, etc.

2. Water quenching method

The water quenching method is to first place the alloy in a quartz tube, and then quench it together with the quartz tube into active water to complete rapid cooling and form a bulk amorphous alloy. There are two ways to complete this process: one is to heat the quartz tube in a closed maintenance atmosphere system (the mouth of the quartz tube should be opened), and the water quenching process is also carried out in a closed maintenance atmosphere system; the other It is to heat the quartz tube directly in the air (the mouth of the quartz tube must be closed at this time), and the tube must be filled with maintenance gas. After the alloy is melted, the quartz tube is quenched into the active water. This method can achieve a higher cooling rate, which is conducive to the formation of bulk amorphous alloys, but there are many problems. For example, the heating and water quenching processes are all carried out in a closed system, and the equipment will be more complicated and expensive; and when the alloy is sealed in a quartz tube, it is not conducive to exhaust gas, and it is easy to form pores. Moreover, in some cases, the quartz tube and the alloy are likely to react to cause the quartz tube to break, and the products after the reaction not only affect the cooling rate of the liquid alloy during water quenching, but also easily form non-uniform nucleation, so that eventually Affects the composition of bulk amorphous alloys. Therefore, the use of this method has great limitations, and I hope everyone should consider this method carefully.

3. Jet forming method

The jet forming method is to place the master alloy in a quartz tube with a small hole at the bottom. After the master alloy is melted, hydrogen is introduced above the quartz tube, and the liquid master alloy will be ejected from the small hole under the effect of pressure and injected into the lower part. The water-cooled copper mold cavity is rapidly cooled to obtain an amorphous alloy. This method has a higher cooling rate and a stronger ability to form amorphous. However, this method is more complicated and technically difficult, and it is possible to obtain amorphous powder in the end.

4. Copper mold suction casting method

This method is generally used for the preparation of amorphous alloy bulk materials. After the master alloy is melted, the melt is sucked and cast from the crucible into a water-cooled copper mold to form a bulk material with a certain shape and size. The master alloy can be melted by induction heating or arc melting. In order to reduce the heterogeneous nucleation of the cavity in the copper mold, the surface of the cavity of the mold can be specially treated. The problem with this method is that the surface of the sample is shortened due to the rapid condensation of the alloy melt in the copper mold. The cavities form voids, which then result in a decrease in the cooling rate of the sample or insufficient lubrication on the surface of the sample.

5. Induction heating copper mold casting method

In this method, the alloy is placed in a quartz tube with a hole at the bottom, and the alloy is rapidly melted by the eddy current heating in the alloy by the induction coil. Because the surface tension prevents the liquid alloy from actively dripping, it is necessary to apply a positive air pressure from the top of the quartz tube to blow it into the copper mold. Compared with the arc heating suction casting method, the induction heating casting method has the advantages of strong controllability of heating temperature, and the copper mold is not directly heated, but it is easier to mix maintenance gas during casting, and finally form pores.

6. Pressure model casting method

First, the alloy is melted in the melting cavity, and then the molten alloy is pressed into the metal mold cavity at a certain speed and pressure to complete the rapid cooling to form a bulk amorphous alloy. Because the liquid metal fills the metal mold cavity quickly and maintains a large pressure, compared with metal mold casting, this method has a faster cooling rate, which is more conducive to the formation of bulk amorphous alloys. The liquid metal is well filled, and it can directly make large-scale amorphous alloy devices with complex shapes. However, this kind of craftsmanship is more difficult than the previous methods, and the skills are more complicated and not easy to operate.

7. Maglev smelting copper mold cooling method

There is no contact or soft touch between the melt and the crucible, the temperature of the melt can be measured by a non-contact method, and the melt is sprayed into the lower copper mold at a suitable temperature. The advantage of this method is that the melt does not touch or softly touch the tower wall, which prevents heterogeneous nucleation in the quenched state, which is conducive to glass formation. The disadvantage is that due to the suspension ability and constraints, only relatively small samples can be prepared. Magnesium-based and zirconium-based alloys can be made into plate-shaped thoroughly amorphous samples with a diameter of 4mm or a cross-section of 4mmx6mm, and various mechanical property tests can be carried out.

8. Directional condensation casting method

This method needs to control the directional condensation rate and the liquid phase temperature gradient at the front of the solid/liquid interface. The theoretical cooling rate that directional condensation can achieve can be budgeted by the product of two parameters, namely R=GV. It can be seen that the larger the temperature gradient G, the higher the directional condensation. The faster the rate V, the greater the cooling rate, and the larger the cross-sectional size of the amorphous that can be prepared. This method is suitable for producing samples with small but relatively long cross-sectional areas.

The comparison and analysis of various amorphous welding alloy preparation methods are as follows:

The water quenching method is simple in operation, simple in equipment, and simple in process control, but has certain limitations. This method should not be used for alloy melts that have a strong reaction with quartz tubes. In addition, its melt cooling rate is not as high as that of copper molds. Arc melting copper mold suction casting method, arc melting alloy has no pollution, good uniformity, fast cooling rate of copper mold, high preparation efficiency, but the prepared sample size is relatively small; induction heating copper mold casting method, in the process of preparing alloy The sealed quartz tube system is selected, which has a fast cooling rate, but is easy to form pores, and the size of the sample is limited; the jet forming method is suitable for preparing small-scale metallic glass samples, and the water-cooled copper mold is used for cooling, and the sample has no significant pores; The pressure model casting method has great potential in improving the quality of castings. In the process of preparing metallic glass, the cooling rate is fast, which can effectively prevent defects such as pores and shortening. The directional condensation method is suitable for samples with small but relatively long cross-sectional areas. , and requires a higher glass composition. Amorphous alloys prepared by powder metallurgy are not only required to be dense, but also required to prevent crystallization, so they are greatly restricted in terms of purity, density, size and shape.

In summary, we can see that the copper mold suction casting method and the amorphous bar direct composite blasting welding method are widely used in industrial production. Therefore, in the preparation of amorphous welding alloys, these two methods can be selected, which will make the prepared amorphous alloys better, which is more conducive to the use of industry and everyone, and thus also makes the production rate more efficient.