Development and crystallization kinetics of novel near-equiatomic high-entropy bulk metallic glasses

In this study, alloying method has been adopted to develop novel near-equiatomic high-entropy bulk metallic glasses (HE-BMGs) with high glass-forming ability (GFA). A class of quinary Zr₃₁Ti₂₇Be₂₆Cu₁₀M₆ (M = Ag, Al, Ni, V, Cr, and Fe) and senary Zr₂₈Ti₂₄Be₂₃Cu₉Ni₁₀N₆ (NV, Cr, Fe, Ag, and Al) alloys were designed. Based on the phase formation rules of high entropy alloys (HEAs), all the developed compositions fall into the zone in which bulk metallic glasses will form. Accordingly, fully glassy rod samples with diameters ranging from 6 to 15 mm have been successfully prepared by copper mould casting. The developed HE-BMGs also possess high specific strength and certain compressive plasticity. Compared with the senary alloys, the quinary alloys possess higher GFA, better plasticity but lower strength. Among these alloys, Zr₃₁Ti₂₇Be₂₆Cu₁₀Ni₆, Zr₃₁Ti₂₇Be₂₆Cu₁₀V₆ and Zr₃₁Ti₂₇Be₂₆Cu₁₀Ag₆ HE-BMGs have been chosen for further non-isothermal analyses according to their large glass forming ability. The apparent activation energies were calculated using Kissinger, Moynihan, Ozawa and Boswell methods. The local Avrami exponents and kinetic fragility were also studied. Based on the experimental results, we have discussed the high entropy effect on the GFA, mechanical properties and crystallization kinetics of developed HE-BMGs.