Bulk metallic glass manufacturing process: technological innovation leads future material development

The bulk metallic glass manufacturing process has achieved significant technological breakthroughs in recent years, which not only improves the performance of the material, but also significantly reduces production costs, allowing it to be used in more fields. This article will introduce in detail the technical principles and methods of the bulk metallic glass manufacturing process.

1.Overview of bulk metallic glass

Bulk metallic glass, also known as amorphous alloy, is a material with a unique atomic structure. Its atomic arrangement is not as orderly as traditional crystals, but appears in a disordered state. Due to the particularity of its structure, this material exhibits many excellent physical and chemical properties, such as high strength, good corrosion resistance, and excellent magnetism.

2.Development background of bulk metallic glass manufacturing process

Research on metallic glasses began in the 1960s, when scientists at the California Institute of Technology successfully prepared the first metallic glass through rapid solidification technology. With the development of materials science, the types and application fields of metallic glasses continue to expand. Especially in the 1980s, Japanese scientists developed a series of bulk metallic glasses that did not contain precious metals, which greatly promoted the practical application of this material. In recent years, with the continuous advancement of bulk metallic glass manufacturing processes, its performance and production costs have been further optimized, and its applications in fields such as electronics, aerospace, and sports equipment have become increasingly widespread.

3.Technical principles of bulk metallic glass manufacturing process

(1) Formation of amorphous structure

The key to the bulk metallic glass manufacturing process is the cooling rate. When a metal or alloy cools rapidly from its liquid state, the atoms do not have time to form an ordered crystal structure and instead form a disordered solid-state structure. The formation of this structure requires avoiding the formation and growth of crystal nuclei, which is usually achieved by controlling the cooling rate. Rapid cooling does not allow enough time for the atoms to arrange into long-range order, resulting in an amorphous structure.

(2) Cooling rate and critical size

The critical size refers to the smallest sample size that can form a completely amorphous structure. This size is closely related to the material’s glass-forming ability. Materials with strong glass-forming abilities can form larger bulk metallic glasses at lower cooling rates. The cooling rate is one of the key factors affecting the formation of amorphous state. The faster the cooling rate, the easier it is to form an amorphous structure. Therefore, in actual production, controlling the cooling rate is one of the key steps in the bulk metallic glass manufacturing process.

4.Bulk metallic glass manufacturing process – traditional method

(1) Rapid cooling method

The rapid cooling method is a common method in the bulk metallic glass manufacturing process. Its basic principle is to cool the metal liquid at an extremely fast speed so that it has no time to form a crystal structure during the solidification process, thereby forming an amorphous structure. This method is usually implemented by spraying the metal liquid onto a high-speed rotating cooling drum, or spraying it into cold water through high pressure. This technology can effectively control the cooling rate and is the main method for producing thin ribbons and filaments of metallic glass.

(2) Melt spin quenching method

The melt spin quenching method is a method that sprays the metal melt onto a high-speed rotating cooling surface and uses centrifugal force to disperse the melt into thin sheets, thereby rapidly cooling it to form metallic glass. This process is suitable for producing larger area metallic glass sheets. By adjusting the spray speed and rotational speed of the cooling surface, the thickness and properties of the metallic glass can be controlled. The melt spin quenching method is widely used in industry to produce high-performance metallic glass materials.

5.Bulk metallic glass manufacturing process – key methods

(1) Metal mold casting method

Metal mold casting is a commonly used bulk metallic glass manufacturing process. This method injects molten alloy liquid into a water-cooled metal mold, usually a copper mold, because copper has good thermal conductivity and can help achieve rapid cooling. This method enables the production of relatively large-sized metallic glass products that are suitable for a variety of alloy systems. The advantages of the metal mold casting method are simple equipment, easy operation, and suitable for industrial-scale production.

(2) High pressure mold casting method

High-pressure die casting involves injecting molten alloy into a metal mold under high pressure. This approach can further increase the cooling rate, allowing even weak glass-forming alloys to form bulk metallic glasses. The high-pressure mold casting method can produce parts with complex shapes and precise dimensions, and is suitable for the manufacturing of high-precision, high-performance products. By optimizing process parameters, efficient and low-cost mass production can be achieved.

(3) Water quenching method

The water quenching method is to put the molten alloy into a quartz tube and then quickly immerse it in water to cool it. This method can provide very fast cooling rates and is suitable for making small-sized bulk metallic glasses. The advantage of the water quenching method is that it has a high cooling rate and can obtain high-quality bulk metallic glass, but the equipment cost is high and the operation is complicated. Suitable for laboratory research and production of small quantities of high-precision products.

(4) Copper mold casting method

Copper mold casting is also a commonly used bulk metallic glass manufacturing process. This method injects molten metal liquid into a copper mold and uses copper’s high thermal conductivity to quickly absorb heat and cool the metal liquid quickly to form an amorphous structure. The copper mold casting method can produce larger metallic glass parts and is widely used in industrial fields that require high strength and corrosion resistance.

(5) Pour casting method

The pour casting method is a method of tilting the casting mold to slowly drip the molten metal into the mold, which avoids the impurity problem in traditional casting methods and helps to improve the purity and quality of metallic glass. This method is suitable for producing high-purity, high-performance bulk metallic glass. By controlling the pouring speed and mold temperature, uniform cooling is achieved and internal defects are avoided.

(6) Squeeze casting method

The squeeze casting method squeezes molten metal into a mold under high pressure and is suitable for manufacturing parts with complex shapes and high strength requirements. This method can effectively improve the density and mechanical properties of metallic glass. The advantage of the squeeze casting method is that it has high production efficiency and is suitable for mass production. By optimizing process parameters, high-quality, high-performance product manufacturing can be achieved.

6.Manufacturing challenges and solutions for bulk metallic glass manufacturing processes

(1) Impurity control and purity issues

During the preparation process of bulk metallic glass, the presence of impurities can seriously affect the quality and performance of the product. Therefore, controlling the content of impurities is an important challenge in the bulk metallic glass manufacturing process. The use of high-purity raw materials and strict process control can effectively reduce the impact of impurities. In addition, the use of advanced purification technologies, such as electron beam melting and zone melting, can also further improve the purity of the material. Electron beam melting heats materials with high-energy electron beams and can remove impurities at high temperatures; zone melting purifies materials through local heating and solidification.

(2) Heat treatment and performance optimization

Heat treatment is a key step in tuning the properties of bulk metallic glasses. By precisely controlling heating temperature and cooling rate, the mechanical properties and stability of metallic glasses can be optimized. For example, proper heat treatment can release internal stress and improve the toughness and strength of the material. Heat treatment can also adjust the microstructure of metallic glasses, thereby improving their physical and chemical properties. By studying the impact of different heat treatment processes on material properties, the optimal heat treatment plan can be formulated to optimize performance.

(3) Cost control and economic benefits

The production cost of bulk metallic glass is relatively high, mainly due to the special equipment and processes required for its manufacturing process. Therefore, reducing production costs is the key to promoting its widespread application. By optimizing the bulk metallic glass manufacturing process and improving production efficiency and product qualification rate, production costs can be effectively controlled. In addition, the development of new low-cost manufacturing technologies is also an important way to achieve economic benefits. For example, the use of high-efficiency production technologies such as high-pressure mold casting and copper mold spray casting can reduce production costs and improve economic benefits while ensuring product quality.

(4) Improvement of amorphous formation ability

Improving the amorphous formation ability of metallic glasses is an important topic in materials science. To achieve this, scientists often design multi-element alloy systems by adding multiple elements to suppress crystal formation. In addition, by optimizing the bulk metallic glass manufacturing process, such as adjusting the cooling rate and melt processing conditions, the amorphous formation capability can also be effectively improved. The design of multi-element alloy systems requires consideration not only of the types and proportions of elements, but also of their interactions and their impact on overall properties.

(5) Methods to avoid crystallization

Crystallization is an important issue that needs to be avoided during the manufacture and use of bulk metallic glasses. Crystallization causes the material to degrade and lose its unique amorphous properties. In order to prevent crystallization, the heating temperature and time can be controlled to avoid the material staying in the sensitive temperature range for a long time. In addition, adding certain elements, such as rare earth elements, can effectively inhibit the formation and growth of crystal nuclei and maintain the amorphous structure of the material. Through reasonable composition design and process control of the bulk metallic glass manufacturing process, the service life and application scope of metallic glass can be effectively extended.

7.Summary

As a material with unique properties, bulk metallic glass’s manufacturing processes and application fields are constantly developing and expanding. By optimizing the manufacturing process of bulk metallic glass and improving material properties, bulk metallic glass will play a more important role in the high-tech field in the future.