Nonisothermal crystallization kinetics of Cr‐rich metallic glass Cr_29.4Fe_29.4Mo_14.7C_14.7B_9.8Y₂ with desirable properties

Abstract

The nonisothermal crystallization kinetics for the first crystallization event of Cr-rich metallic glass (MG) Cr 29.4 Fe 29.4 Mo 14.7 C 14.7 B 9.8 Y 2 with desirable properties was systematically studied by Kissinger, Ozawa, Kissinger-Akahira-Sunose (KAS), Ozawa-Flynn-Wall (OFW), and Vogel-Fulcher-Tammann approaches using differential scanning calorimeter. The apparent activation energy (E) for characteristic temperatures deduced by Kissinger approach is comparable with that deduced by Ozawa approach. The E g for the glass transition temperature is smaller than the E p1 for the peak temperature of the first crystallization event and larger than E for other characteristic temperatures, exhibiting that the glass transition is easier than the growth process of the first crystallization event and more difficult than other processes. The local activation energy estimated by KAS and OFW approaches shows approximate tendency of increasing initially and then gradually decreasing, which indicates that the crystallization process is difficult at first and then gradually becomes easy. The local Avrami exponent (n(x)) changes from n(x) > 2.5 to 1.5 < n(x) < 2.5 for crystallization under low heating rate and from n(x) > 2.5 to 0 < n(x) < 1.5 for crystallization under high heating rate, corresponding to a diffusion-governed crystallization changing from enhancing nucleation rate to reducing nucleation rate under low heating rate and from enhancing nucleation rate to preexisting nuclei under high heating rate, respectively. The kinetic fragility parameter shows that the glass-forming liquid of the present MG is intermediate type with moderate glass-forming ability. The results would provide comprehensive insights to understand the formation of Cr-rich MG.