Feb/March_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | F E B R U A R Y / M A R C H 2 0 2 1 1 1 DEFYING CONVENTIONAL METALLURGY Researchers from the University of New South Wales, Sydney, along with international collaborators, dis- covered that diverse types of patterns occur at the surface of solidified metal alloys. The team used two-component metallic mixes, such as gallium-based alloys containing small amounts of bis- muth. With electron microscopy, they were able to observe a kaleidoscope of highly ordered patterns including alternating stripes, curved fibers, dot arrays, and some exotic stripe-dot hybrids on the metallic surfaces. The team found that, when these pat- terns are formed, the abundance of the low-concentration element bis- muth at the surface region was notably increased. Such surface enrichment found in this study defies conventional metallurgical understandings. The researchers related the magic behind this newly observed solidifica- tion phenomenon to the unique surface structures of liquid metals. “This pre- viously ignored surface solidification phenomenon improves our fundamen- tal understanding of liquid metal alloys and their phase transition processes. In addition, this autonomous surface pro- cess can be used as a patterning tool for designing metallic structures and creat- ing devices for advanced applications in future electronics and optics,” says Prof. Kourosh Kalantar-Zadeh, corres- ponding author. www.unsw.edu.au . Stripes, dots, and other exotic patterns on the surface of liquid metal after solidifica- tion. Courtesy of Jialuo Han/UNSW.