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 (N=V, 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, Zr31Ti27 Be26Cu10Ni6, 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. (C) 2018 Elsevier B.V. All rights reserved.