Recently, a European research team used the X-ray of the European synchrotron to study the formation process of metallic glass, and revealed the "glass transition" process of the alloy from liquid to solid from a microscopic perspective. This leap in understanding will have an important impact on the research of metallic glass and other materials in the world.
Metallic glass (also known as amorphous alloy) is an alloy that does not crystallize during rapid (eg, less than 1 second) cooling. Unlike traditional alloys that slowly cool and crystallize, the atoms of metallic glass do not form a regular crystal structure, but rather generally maintain their position in the melt. This makes metallic glass as strong as steel and as elastic as plastic. Since its inception in 1960, due to its high strength, large elastic limit, excellent wear resistance, corrosion resistance, radiation resistance and soft magnetic properties, it has shown broad application prospects in various fields such as national defense, electronic information, and energy high technology.
However, what exactly happened at the atomic level in this "glass transition"? So far it has not been fully clarified. Over the past few decades, understanding how glass is formed has been an important challenge in the field of materials science. Similar research failed more than ten years ago for technical reasons.
Recently, a research team led by Dr. Isabella Galino, a material scientist at the University of Saarland, Germany, has made significant progress in this area. The Galino team conducted unprecedented detailed research with Dr. Xavier Monil and Dr. Daniel Kanjalosi of Spain, and Dr. Beatrice Ruta of France. They used the high-energy X-rays of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France to study a special supercooled melt of gold alloys, especially when it "frozen" from about 150 ° C (liquid) to about 115 ℃ (glass state) this process. They used a new "rapid calorimeter" to study the freezing process itself, and finally succeeded, revealing how its mobility is reduced from the atomic level of the alloy.
Dr. Galino said that it has always been believed that as the atomic mobility decreases, the properties of liquids decrease correspondingly, while the properties of solids increase steadily, but this one-to-one correlation is not entirely correct. Because the alloy melt is composed of different atoms of different sizes. Although large atoms like gold atoms have been frozen, small atoms like silicon can still move. This collective flow means that mobility still exists at this point in time, so the material still behaves like a liquid. Only when the smaller atoms also freeze, the liquid eventually solidifies into glass.
Researchers' understanding of the key process of "glass transition" can help create new materials or understand the characteristics of existing materials. In addition to metallic glass, it will also promote the research of other glass materials (such as polymers and ionic liquids) worldwide.