Glass-forming liquids exhibit unique dynamic transition behavior during temperature changes. The system undergoes a transition from the fragile liquid to the strong liquid, known as the fragile-to-strong transition as the temperature decreases. Addressing the issue of poor glass-forming ability (GFA) in Fe-based alloys, by studying the kinetic behavior of the Fe-Zr-B-M (M = Nb、Ti、Al) alloy system, we aim to reveal the mechanism of ductile-brittle transition and establish the relationship between the degree of ductile-brittle transition and the GFA. In this study, through viscosity measurements, we reveal a pronounced fragile-to-strong transition behavior in this system. Using crystallization activation energy as an evaluation criterion, we establish a negative correlation between the degree of the fragile-to-strong transition and the GFA in the Fe-Zr-B-M system. The results indicate that the crystal-like clusters play a critical role in the solidification process of the Fe-Zr-B-M metallic glasses. Based on this, we propose a fragile-to-strong transition mechanism involving the structural transformation from the icosahedral clusters to the crystal-like clusters. Through theoretical calculations of mixing enthalpy and mismatch entropy, combined with microstructural characterization, we find that alloy compositions with more negative mixing enthalpy and higher mismatch entropy can effectively suppress the tendency of icosahedral structures to transform into crystal-like structures, thereby hindering crystallization and promoting the formation of a more disordered amorphous structure. This structural feature not only corresponds to superior glass-forming ability but also manifests as a weaker fragile-to-strong transition phenomenon. In this work, the intrinsic correlation between viscosity characteristics and the GFA is revealed, providing a theoretical basis for the development of Fe-based metallic glass with high GFA.
Wang et al. (Wed,) studied this question.