Speaker
Description
Metallic glasses are a promising class of materials for a variety of applications. In many ways these amorphous solids outperform their crystalline counterparts. Rapid cooling of metallic melts to temperatures below a characteristic glass-transition temperature is necessary to avoid crystallisation and to obtain the glassy state. However, the only very subtle changes of the atomic structure compared to tremendous changes of macroscopic properties like viscosity during cooling and glass formation constitute the main challenge for a deeper understanding of the prerequisites determining the glass-forming ability of a given alloy [1,2]. This, in turn, hampers the broader applicability of metallic glasses to date.
Here we discuss structural changes in glass-forming metallic liquids from temperatures well above the liquidus temperature to well below the glass transition temperature monitored in-situ by ultrafast high-energy X-ray diffraction in a containerless levitation setup. This enables a detailed investigation of the structural changes leading to the significant slowdown of the atomic kinetics during glass formation [1,2]. Analysis of the short and medium range order along the liquid alloy’s pathway to the glassy state also shows structural changes indicating possible liquid-liquid transitions [1] and the effect of global electronic interactions on structure formation [3].
[1] K. Georgarakis, L. Hennet, G.A. Evangelakis, J. Antonowicz, G.B. Bokas, V. Honkimaki, A. Bytchkov, M.W. Chen and A.R. Yavari, Probing the structure of a liquid metal during vitrification, Acta Mat. 87 (2015) 174.
[2] D.V. Louzguine-Luzgin, R. Belosludov, A.R. Yavari, K. Georgarakis, G. Vaughan, Y. Kawazoe, T. Egami and A. Inoue, Structural basis for supercooled liquid fragility established by synchrotron-radiation method and computer simulation, J. Appl. Phys. 110 (2011) 043519.
[3] M.E. Stiehler, M.R. Jolly, K. Georgarakis, On the impact of global interactions on the structure of metallic glasses, J. Alloys Compd. 782 (2019) 496.
| Speaker Country | United Kingdom |
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