Maximum supercooling studies in Ti_39.5Zr_39.5Ni₂₁, Ti₄₀Zr₃₀Ni₃₀, and Zr₈₀Pt₂₀ liquids - Connecting liquid structure and the nucleation barrier

Almost three quarters of a century ago, Charles Frank proposed that the deep supercooling observed in metallic liquids is due to icosahedral short-range order (ISRO), which is incompatible with the long-range order of crystal phases. Some evidence in support of this hypothesis had been published previously. However, those studies were based on a small population of maximum supercooling measurements before the onset of crystallization. Here, the results of a systematic statistical study of several hundred maximum supercooling measurements on Ti_39.5Zr_39.5Ni₂₁, Ti₄₀Zr₃₀Ni₃₀, and Zr₈₀Pt₂₀ liquids are presented. Previous X-Ray and neutron scattering studies have shown that the structures of these liquid alloys contain significant amounts of ISRO. The results presented here show a small work of critical cluster formation (W^∗ = 31-40 k_BT) from the analysis of the supercooling data for the Ti_39.5Zr_39.5Ni₂₁ liquid, which crystallizes to a metastable icosahedral quasicrystal. A much larger value (W^∗ = 54-79 k_BT and W^∗ = 60-99 k_BT) was obtained for the Ti₄₀Zr₃₀Ni₃₀ and Zr₈₀Pt₂₀ liquids, respectively, which do not crystallize to an icosahedral quasicrystal. Taken together, these results significantly strengthen the validity of Frank's hypothesis.