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Properties of (TiZrNbCu)_1-xNi_x Metallic Glasses

Recent study of the electronic structure and properties of (TiZrNbCu)1-xNix (x≤0.25) amorphous high entropy alloys (a-HEA [1]) has been extended to x=0.5 in order to compare the behaviours of a- HEA and a conventional Ni-base metallic glasses (MG). All samples were ribbons about 20 μm thick and their fully amorphous state was verified by thermal analysis and X-ray diffraction (XRD). XRD patterns were also used in order to deduce the nearest neighbour distances and probable local atomic arrangements [1, 2]. Precise composition and the distribution of components were studied with a scanning electron microscope (SEM) with an energy dispersive spectroscopy (EDS) attachment. Here we studied thermal parameters (the glass transition temperature Tg, the first crystallisation temperature Tx and the melting and liquidus temperatures Tm and Tl respectively), the low temperatures specific heat (LTSH [1]), the magnetic susceptibility χexp and the Young's modules E. Except for E which was measured both for as-cast and relaxed ribbons (after a short anneal close to Tg) all other properties were measured on as-cast samples only. The LTSH showed that the electronic density of states of the Fermi level N(EF) decreases with increasing x, whereas the Debye temperature ΘD increases with x [1]. This is similar to what observed in binary and ternary MGs [2, 3] of early transition metals (TE) with late transition metals and indicates that N(EF) is dominated with the d-electrons of TE . Like ΘD , E, Tx and Tl increased with increasing x indicating the enhanced inter- atomic bonding on addition of Ni (similar to that observed in binary TE-Ni MGs [2, 4]). However Tx and Tl tend to saturate for x≥0.25 which seems to support a change in local atomic arrangement around x=0.25 deduced from the analysis of XRD patterns. The usual parameters associated with glass forming ability (GFA) showed little variation with x, thus no real change in GFA when going from a-HEA to conventional MGs in the studied system. As expected [1], the rule of mixtures gave poor description for most properties of our alloys. 1. K. Biljaković et al, J. Alloys Compd. 695, 2661 (2017). 2. R. Ristić et al, J. Alloys Compd. 621, 136 (2015). 3. R. Ristić et al, Solid State Commun. 151, 1014 (2011). 4. R. Ristić , M. Stubičar, E. Babić, Phil. Mag. 87, 5629 (2007).

Metallic glasses, HEA

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