Scientists discover metallic liquid alloys with zebra or leopard patterns

Around 1952, the famous mathematician Alan Turing developed a conceptual model to explain the process

formation of patterns of a two-component system. Such patterns are hereinafter also referred to as Turing patterns.

Pattern formation is also widely used inartificial systems and industry, especially in the field of metallurgy. There is a whole area called "metallography", which specializes in the study of microscale structures and compositions of metals and alloys. If you split a multicomponent alloy and look at its cross-sections, it is likely that you will see alternating stripes or overlapping spots of different metal components in the cut. However, despite the fact that the structure and models of solidification of liquid alloys have been known for a long time, the phenomenon of the formation of their surface pattern has remained unexplored for a long time.

Jialuo Han, UNSW

Researchers examined exactly what types of patternsare found on the surface of solidified metal alloys. The team used two-component metallic mixtures: gallium-based alloys containing small amounts of bismuth. These alloys melt easily in the hand, making experimental observation and control easier.

“We could observe the solidification processsurface under a conventional optical microscope, and I was surprised when I first saw a solidification front on the surface of a liquid metal, creating continuous patterns behind it, ”says Dr. Jianbo Tang, lead author of the work.

Using electron microscopes, scientists studiedhighly ordered patterns, including alternating stripes, curved fibers, dot arrays, and some exotic strip and dot hybrids. The researchers were surprised that during the formation of these structures, the content of bismuth with a low concentration in the surface region increased significantly. Such surface enrichment found in this study is contrary to conventional metallurgical concepts.

Researchers have linked the discovered phenomenonsolidification with a unique surface structure of liquid metals, and supercomputers were used to simulate this process. In computer simulations, few bismuth atoms, apparently randomly moving in the sea of ​​gallium atoms, accumulated on the alloy surface.

“This previously ignored phenomenonSurface solidification improves our fundamental understanding of liquid metal alloys and their phase transition processes. This self-contained surface process can be used as a drawing tool to design metal structures and create devices for advanced applications in future electronics and optics, ”added Professor Kurosh Kalantar-Zade, co-author of the study.