Defect-induced ordering and disordering in metallic glasses

AS Makarov and RA Konchakov and J Qiao and AN Vasiliev and NP Kobelev and VA Khonik, INTERMETALLICS, 163, 108041 (2023).

DOI: 10.1016/j.intermet.2023.108041

On the basis of shear modulus measurements on a Pt-based glass, we calculated temperature dependence of the defect concentration c using the Interstitialcy theory. This temperature dependence is compared with temper-ature dependence of the normalized full width at half maximum (FWHM) & gamma; of the first peak of the structure factor S(q) for the same glass available in the literature. It is found that & gamma; above the glass transition temperature Tg linearly increases with c in the same way for both initial and relaxed (preannealed) samples providing the ev-idence of defect-induced disordering in the supercooled liquid region independent of glass thermal prehistory. For both states of the samples, the derivative d & gamma;/dc is close to unity. Below Tg, the interrelation between & gamma; and c is entirely different for initial and relaxed samples. In the former case, strong defect-induced ordering upon approaching Tg is observed while relaxed samples do not reveal any clear ordering/disordering. Possible reasons for these observations are discussed. To further investigate the relationship between the normalized FWHM and defect concentration, we per-formed molecular dynamic simulation of & gamma; (c)-dependence in a high-entropy FeNiCrCoCu model glass. It is found that & gamma; also linearly increases with c while the derivative d & gamma;/dc is again close to unity just as in the case of Pt-based glass.

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