Crystallization kinetics of Hf28Be18Ti17Zr17Cu7.5Ni12.5 high-entropy bulk metallic glass

Abstract

Crystallization kinetics of Hf28Be18Ti17Zr17Cu7.5Ni12.5 high-entropy bulk metallic glass (HE-BMG) in the non-isothermal and isothermal conditions were investigated by differential scanning calorimetry (DSC). In non-isothermal crystallization condition, DSC traces exhibited three crystallization processes. The apparent activation energies of peak crystallization temperatures were calculated by Kissinger methods and found to be Ep1 > Ep2 > Ep3. The dependence of local activation energy on crystallized volume fraction was summarized by the Kissinger-Akahira-Sunose (KAS) method. The non-isothermal crystallization reaction was described mathematically using the Šesták-Berggren model. In the isothermal crystallization condition, with the increase of annealing temperature, the incubation time and crystallization time become shorter and the crystallization peak becomes higher. All Avrami indices were less than 2.5, indicating that crystallization of glassy alloy is dominated by a diffusion-controlled three-dimensional growth with a decreasing nucleation rate.