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Atomic short range order and properties of (TiZrNbCu)_1-xNi_x glassy alloys

A comprehensive study of selected properties of (TiZrNbCu)1-xNix (x≤0.5) glassy alloys has been performed. The samples were ribbons about 20 μm thick and their fully amorphous state was verified by X-ray diffraction (XRD) and thermal analysis (DSC/DTA). The surface morphology, actual composition and the distribution of components were studied with Scanning electron microscope with an energy dispersive spectroscopy attachment. The properties studied were average interatomic distances and probable atomic short range order (SRO), thermal stability parameters, low temperature specific heat (LTSH), the magnetic susceptibility χ and the Young’s modulus. The XRD results for x≤0.25 (high entropy alloys, HEA) indicated [1] a bcc-like SRO (similar to that in corresponding crystalline HEA with x≤0.2 [2]), and the behaviour of their properties was similar to that observed in binary Ti, Zr- Ni, Cu glassy alloys [3]. In particular, electronic density of states at the Fermi level (dominated with d-states of TiZrNb [4]) and χ decreased on increasing x, whereas the properties associated with interatomic bonding (thermal, vibrational and elastic parameters) increased with increasing x. An extension of this study to x≤0.5 indicates a change in SRO from bcc-like to fcc-like for x≥0.25 (which is consistent with valence electron number, VEC≥7 criterion for stability of fcc structure in crystalline HEA [1]) which strongly affects the variation of all physical properties with x in these alloys. Here, we discuss parameters derived from XRD and DSC/DTA analyses. The glass forming ability and the applicability of the rule-of- mixtures are also briefly discussed. [1] K. Biljaković et al , J. Alloys Compd.. 695 (2017) 2661. [2] A. Cunliffe, J. Plummer, I. Figueroa, I. Todd, Intermetallics 23 (2012) 204. [3] R. Ristić, J. R. Cooper, K. Zadro, D. Pajić, J. Ivkov, E. Babić , J. Alloys Compd. 621 (2015) 136. [4] U. Mikšić., P. Pervan, UPS results, private comm. (2017).

Metallic glasses ; HEA ; SRO

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