Electronic Structure and Glass Forming Ability in Transition Metal Alloys

Recently we reported a correlation between the change in magnetic susceptibility upon crystallization of Cu-Zr, Hf metallic glasses and glass forming ability (GFA) in these alloys [1]. In particular we have shown that a small difference in magnetic susceptibilities of corresponding amorphous and crystalline alloys reflects high GFA (represented by high value of the reduced glass transition temperature Trg=Tg/Tl , where Tg and Tl are the glass transition and liquidus temperatures, respectively). Further, we have shown that this correlation stems from similar electronic structures, ES (represented by the electronic density of states at the Fermi level, N(EF)) of amorphous and corresponding crystalline alloy [1, 2]. Here we extended a study of this correlation by investigating the magnetic susceptibilities over a broad composition range in several Ti-Cu, Zr-Cu and Zr-Ni alloys. In particular we studied a change of magnetic susceptibility upon crystallization in five Ti-Cu and four selected Zr-Cu and Zr-Ni metallic glasses. Actual compositions of Zr-Cu and Zr-Ni alloys were selected to complete and verify the literature results for these alloy systems [3, 4]. The methods employed for magnetic susceptibility measurements and crystallization of studied alloys were the same as in our previous report [1]. The fully crystalline final state of all our alloys was verified by x-ray diffraction patterns. An important novel feature of a present study is that we use the experimental critical casting thickness dc which is directly related to GFA to describe the variation of GFA with composition in Ti-Cu, Hf-Cu and Zr-Cu alloys. (Since for Zr-Ni alloys dc data do not exist we described the variation of GFA in these alloys by using the empirical GFA criteria such as Trg.) For all four studied alloy systems, very good correlation between dc and / or other criteria for high GFA and the change in magnetic susceptibility upon crystallization of metallic glasses has been obtained. The correlation between ES and GFA in these alloys also showed up the best in Zr-Cu alloys (where also the data for the change in N(EF) upon crystallization are available [2]) and in Zr2Ni alloy which exhibits a local maximum in GFA due to virtually no difference between N(EF) of metallic glass and corresponding intermetallic compound. The applicability of this criterion for GFA (which provides a simple way to select the composition with high GFA) to other metal-metal metallic glasses (including ternary and multicomponent bulk metallic glasses) is briefly discussed. 1. R. Ristić et al, EPL 114, 17006 (2016). 2. P. Garoche and J. Bigot, Phys. Rev B 28, 6886 (1983). 3. Z. Altounian, T. Guo-Hua and J. O. Strom- Olsen, J. Appl. Phys. 53, 4755 (1982). 4. Z. Altounian, T. Guo-Hua and J. O. Strom- Olsen, J. Appl. Phys. 54, 3111 (1983).