On September 25, Wang Weihua, academician of the Chinese Academy of Sciences and director of the Songshan Lake Materials Laboratory, delivered a speech titled "Industrial Application and Development Opportunities of Amorphous Materials" at the "2020 China New Materials Capital Technology Conference".
Obtaining new materials by modulating the "order" or "entropy" of the material structure is a new concept and new way to explore new materials in recent years.
Among them, the atomic arrangement of amorphous materials is microstructure and long-range disorder, which overturns the thinking and methods of traditional metal materials processing and preparation, and is playing more and more in high-tech fields such as energy, information, national defense, aerospace, medical and health. The more important the role.
Because it is a cutting-edge new material, the biggest key problem of amorphous materials is insufficient formation ability. "Not all metals can be made into amorphous materials. Amorphous alloys require a fast cooling rate, so conditions such as high vacuum, high purity, and high cooling are required, resulting in high material costs."
Academician Wang Weihua believes that the forming ability of amorphous alloys is a key shortcoming of technology and application, and he and his team are currently working on key issues. "Our goal is decimeter-level amorphous alloys. By introducing new concepts, core designs, high throughput, and advanced manufacturing methods, we will develop new systems and break through size limitations."
The magical amorphous alloy
As we all know, the microstructure determines the material properties.
The atoms or molecules of crystalline materials are arranged repeatedly in space according to a certain regular cycle, while the atomic arrangement of amorphous materials is chaotic and disorderly, and there are many differences in performance between the two.
Based on crystalline materials, a cross-scale relationship between micro-scale atomic structure and macro-scale properties can be established, and the material properties can be adjusted by modulating the structure. The disordered system of amorphous materials is difficult to establish cross-scale relationships.
"But for this reason, in addition to being a material, amorphous materials are also a model system that allows researchers to study materials science in a deeper and more extensive way." Academician Wang Weihua said that the history of amorphous materials is very old. After the metal is made into an amorphous state, the category of amorphous materials is expanded. "Amorphous alloys are a new type of metal material developed in the past five to sixty years."
The preparation method of amorphous alloys is different from that of metal materials by melting first and then casting. Academician Wang Weihua explained: “The current rapid cooling technology is developing rapidly, and the disordered metal atoms under high temperature are “fixed” before they can be arranged neatly. In this way, amorphous alloys are obtained. Of course, there are many preparation methods, such as amorphous Strips, amorphous bars, amorphous samples, etc."
Developed along this line of thinking, when steel, aluminum alloy, and titanium alloy are prepared into amorphous materials, the performance changes greatly. Soft magnetic, degradable, large elasticity, high strength and high toughness, catalysis, thermoplasticity, corrosion resistance and wear resistance, etc. are the properties obtained after being made into amorphous alloys, which has opened up many paths for the application of amorphous alloys and formed huge applications Group, "Soft-magnetic amorphous alloy is currently the most effective and most abundant material."
Academician Wang Weihua emphasized that the new materials are ultimately used in the industry and must be made into corresponding shapes as needed before they can be used. The reason why metals and plastics are widely used in various fields of modern industry and life, in the final analysis, lies in the merits and subtleties of plastic processing. Amorphous alloys also have processing and forming characteristics and can undergo superplastic processing deformation in the supercooled liquid phase region.
Regarding the use of this characteristic of amorphous alloys, Academician Wang Weihua revealed: “In 2005, the new metallurgical process that we studied in the extreme environment of the laboratory can make amorphous alloys blow molded like glass, perform micro and nano processing, and make More complicated shapes."
This may provide new ideas and methods for short-process, near-formed energy-saving metal material processing, and it is a way of subverting traditional metal material processing and preparation.
"Treasure" materials in the high-tech field
Amorphous alloys are widely used in high-tech fields. Consumer electronics, key components of aerospace, high-end manufacturing, and new energy fields are all available "stages".
Academician Wang Weihua said that the team’s research results have been implemented in the field of consumer electronics. “We have successfully cooperated with Dongguan enterprises. For example, the use of amorphous alloy die-casting into wireless earphones can not only be precisely die-cast into complex shapes like plastic, but also can obtain more High intensity and better sound effects are welcomed by overseas markets."
In the key components of aerospace, high expectations are placed on the application of amorphous alloys. It is also the main research direction of Academician Wang Weihua and his team in the Songshan Lake Materials Laboratory, covering the research of flexible gears, mirror components and other components.
The elasticity of amorphous alloys is dozens of times higher than that of conventional metals. It is uniquely used for flexible gears. It can work normally even in harsh environmental conditions such as space, without the need to add lubricating oil after entering the sand. "We have developed this type of flexible gear in the Songshan Lake Materials Laboratory, which has obvious advantages over traditional metal materials," said Academician Wang Weihua.
Amorphous mirrors are another direction for academician Wang Weihua’s team in Songshan Lake Materials Laboratory. This is a mirror installed on a space vehicle to image the ground. In the future, as space exploration deepens, it will have a wider range of applications. When the amorphous alloy is used in this equipment, it can meet the requirements of smooth and good reflectivity of the mirror surface, and significantly improve the resolution of ground imaging.
Academician Wang Weihua revealed that the current research on amorphous alloy mirrors has made progress, and the imaging effect in the laboratory is ideal. He hopes that this research can be applied to lunar exploration projects in the future.
Amorphous alloys have more applications. For example, high-strength, high-toughness amorphous alloys are candidates for the third-generation armor-piercing and armor-piercing projectiles. Amorphous alloys with high specific strength and high elastic limit are expected to be used in key components of spacecraft. In addition to these defense applications, amorphous alloys also have application value in high-end manufacturing equipment such as high-speed and high-frequency motors for new energy vehicles, wireless charging devices for mobile phones, and robots.
Making amorphous alloys "bigger" is the key
In the process of new materials from birth to industrialization and even large-scale use, there will always be various problems, which require researchers to continuously explore and verify.
The same is true for amorphous alloys, whose forming ability is weak, and their small size is already a barrier to large-scale applications.
Compared with alloys such as iron and steel, the currently achievable size of amorphous alloys is still at the centimeter level, and the preparation process requires high vacuum, high purity, high cooling, etc., and the cost is extremely high, which greatly limits the expansion of applications. So far, only 10 amorphous alloys have achieved commercial applications.
"One of the keys to the development of amorphous alloys is to find a forming system that can be'made bigger'." Academician Wang Weihua emphasized.
He believes that the current environment is favorable for research on amorphous alloys. "It is hoped that with the help of my country's current development trends, policies and attitudes that strongly support scientific research, a breakthrough in size can be achieved in amorphous alloys."