Amorphous alloys (Amorphous Alloys), also known as metallic glass, refer to a class of alloy materials with long-range disorder and short-range order arranged on the atomic scale. Its microstructure is different from traditional crystalline alloys, and there are no grains and grain boundaries inside. The unique material structure makes the alloy have high specific strength, large elastic deformation capacity, strong corrosion resistance, low thermal expansion coefficient, high wear resistance, excellent soft magnetic properties, and can be widely used in electronic information, aerospace, biomedical, etc. In the field, the market demand is large, and the prospect of industrialization is very broad.
Various countries attach great importance to research and development in the field of amorphous alloys. From 1994 to 2018, the number of published patents in the world was counted every five years as a time node, and the number of patent applications in Japan, the United States, Germany, and China was counted. In the past 15 years, the number of global applications has shown a steady upward trend. Japan, the United States and Germany started earlier in this field, and China has also begun to work hard since the early 2000s, gradually surpassing Japan, the United States and Germany.
Internationally, the United States, Japan, Germany and other countries have invested a lot of money to support the research of amorphous alloys and promote industrial development. Among them, the research and development level, market competitiveness and industrial scale of enterprises represented by Liquidmetal Technologies, Glasmetal Technologies, Hitachi Metals Co., Ltd., Germany, and VAC in Germany are all at the global leading level. On October 16, 2018, Liquidmetal Technologies of the United States successfully used an amorphous alloy LM105 to manufacture a pacemaker housing, which makes it have excellent strength and elasticity, can withstand huge pressure, and greatly reduce costs. Will cause harm to the body.
At present, China's industrialized amorphous alloys are mainly presented in the form of strips, and the most mature application of iron-based amorphous alloys in distribution transformers. The technology of amorphous strips in China is basically the same as that of foreign countries. The quality of strips is very competitive, and the energy saving effect in the application of distribution transformers is very obvious. At present, domestic companies producing amorphous alloys mainly include BJAT Technology Co., Ltd., QDYL New Energy Technology Co., Ltd., DGYA Technology Co., Ltd. and so on. Among them, BJAT Technology Co., Ltd., QDYL Advanced Materials Technology Co., Ltd. and other enterprises mainly focus on the R & D and production of amorphous and nanocrystalline strips, while DGYA Technology Co., Ltd. is an enterprise with large amorphous metal forming capabilities.
Since 2018, there have been many foreign research teams that have made new progress in amorphous alloy preparation, structural cognition, and mechanism research. In order to replace the expensive Pd / Pd-Ag separation membrane, the S.Sarker team of the University of Nevada, USA developed the Ni-Nb-Zr amorphous alloy, which exhibits a high hydrogen permeability at 200 ℃ ~ 400 ℃. Atomic probe tomography confirmed that there was indeed phase separation inside the amorphous alloy, and a nano-scale Nb-rich and Zr-rich amorphous composite structure was formed on the ternary amorphous substrate. Based on density functional theory (DFT) simulations, it is found that these local atomic cluster structures mostly consist of icosahedrons.
In addition, some research teams focus on the service performance and deformation mechanism of amorphous alloys. In October 2018, the team of Sergey V. Ketov of Tohoku University in Japan studied the effect of low-temperature thermal cycle treatment on the mechanical properties of metallic glass with different compositions. Studies have found that low-temperature thermal cycling can both induce structural activation and may lead to relaxation of the metallic glass structure, resulting in increased or decreased plasticity of the material.
In recent years, Chinese scientific research workers have kept pace with the world's development frontiers, and have made breakthroughs in many directions in the field of amorphous alloys, with considerable scientific research achievements. On May 1, 2019, a team of academicians Wang Weihua and Liu Yanhui from the Institute of Physics of the Chinese Academy of Sciences designed an amorphous alloy composed of three metals of iridium (Ir), nickel (Ni) and tantalum (Ta) and boron. The transition temperature is as high as 1162K, and the supercooled liquid region is 136K, which is wider than most metallic glasses. At the same time, the strength of this alloy at 1000K is 3.7 GPa. The author uses a simplified high-throughput combination method to screen some promising alloys by using the correlation between glass forming ability and resistivity. This design method is practical and provides a way to find other high-performance glassy alloys. New ideas; On January 19, 2019, Professor Lu Zhaoping and Associate Researcher Li Hongxiang from the University of Science and Technology Beijing presented a review article that presented the research progress and achievements of iron-based bulk amorphous alloys over the past 20 years, including preparation, Glass forming ability, crystallization characteristics, mechanical properties, corrosion behavior, magnetic properties and industrial applications. In addition, the article points out the future development direction of this subject area based on the author's understanding; in addition, China has made some progress in the design of iron-based amorphous alloys, the simulation research of amorphous alloys, and the deformation mechanism of amorphous alloys.
Industrially, ferromagnetic amorphous alloys have gradually replaced traditional silicon steel sheets due to their excellent magnetic properties, and are widely used as magnetic cores for transformers. In aerospace applications, amorphous alloys can adapt well to changes in space temperature due to their low expansion coefficients, and can be used to prepare disc compression rods and support bars for satellite detectors. However, since the application of bulk amorphous alloys and composite materials still faces many difficulties in composition, structure, performance, process, cost, etc., its initial industrialization is still only the tip of the iceberg in the process of amorphous applications.
In scientific research, the amorphous formation mechanism, performance control and plastic deformation mechanism of amorphous alloys are still the focus of future research, and the auxiliary role played by computer simulation is becoming more and more important. Continue to develop amorphous alloys with more excellent soft magnetic properties and prepare high corrosion-resistant and wear-resistant coatings will remain the focus of the future in the amorphous field. At the same time, the application scope of amorphous alloys will be broadened, seeking biomedical applications, sewage degradation, catalysis, etc The application of more fields will be the basis for the long-term development of amorphous disciplines.