Speaker
Description
Metallic glasses (MGs) are an advance class of engineering alloys in which the atoms, mainly of metallic elements, are arranged disorderly without creating a crystalline structure. The lack of long-range ordering gives rise to various advantageous mechanical (high yield strength, hardness, large elastic limit…), chemical (corrosion and radiation resistance), electronic and/or magnetic (low coercivity, high saturation magnetization, low core loss, high permeability) properties in comparison to their crystalline counterparts. To understand the glass forming ability[1], the temperature stability and devitrification[2], the deformation mechanism[3], radiation resilience[4], the Invar effect in Fe-based MGs[5] and other characteristics, probing the local atomic arrangement and its evolution is essential.
High-energy X-ray diffraction (HEXRD) has proven to be a suitable tool to determine the local atomic structure of MGs. Time-resolved in situ HEXRD experiments performed at high-brilliance synchrotron radiation sources can detect subtle modifications of the amorphous structure when it is exposed to a variety of external factors (low and high temperature, tensile and compressive forces, heavy ions, different chemical environments…). However, to unambiguously identify the contributions of individual atomic pairs in multicomponent systems, the involvement of other complementary atomic-sensitive techniques is usually crucial. Among them, neutron diffraction has a special position due to its ability to provide scattering contrast that differs from that of HEXRD for various elements[6]. Finally, neutron and diffraction datasets may be employed together in simulation techniques such as the Reverse Monte Carlo method to provide a real-space information at the atomic level[6].
References
[1] A. Lachová et al., ‘Modification of structural, mechanical, corrosion and biocompatibility properties of Ti40Zr10Cu36Pd14 metallic glass by minor Ga and Sn additions’, J. Alloys Compd., vol. 940, p. 168776, Apr. 2023, doi: 10.1016/j.jallcom.2023.168776.
[2] Š. Michalik et al.,‘In situ HEXRD study of a Ca61Al39 metallic glass’, J. Alloys Compd., vol. 687, pp. 188–196, Dec. 2016, doi: 10.1016/j.jallcom.2016.06.094.
[3] J. Bednarcik et al.,‘In situ tensile deformation of Fe-rich metallic glass at elevated temperatures using hard X-ray diffraction’, J. Alloys Compd., vol. 509, pp. S92–S94, 2011.
[4] Š. Michalik et al.,‘The effects of swift Xe ion bombardment on the amorphous structure of a VITROPERM type alloy’, J. Alloys Compd., vol. 795, pp. 69–78, Jul. 2019, doi: 10.1016/j.jallcom.2019.04.328.
[5] A. Firlus et al., ‘Atomic structure evolution related to the Invar effect in Fe-based bulk metallic glasses’, Nat. Commun., vol. 13, no. 1, p. 1082, Dec. 2022, doi: 10.1038/s41467-022-28650-9.
[6] Š. Michalik et al., ‘Short range order and crystallization of Cu–Hf metallic glasses’, J. Alloys Compd., vol. 853, p. 156775, Feb. 2021, doi: 10.1016/j.jallcom.2020.156775.
