Viscosity and Structure Studies of Iron-Based Quaternary Melts: The Effect of S

This study systematically explores the foundational principles and mechanisms governing viscosity across the entirety of Fe-4.5wt%C-0.1wt%Ti-xS melts. The element sulfur (S) imparts discernible effects on system viscosity at diverse temperature intervals. In the solid-liquid phase boundary, an increase in S content precipitates a more pronounced formation of solid-phase particles within the system, consequently resulting in an elevated viscosity during this phase as S content increases. Conversely, within the pure liquid phase, S functions as an interstitial atom, inducing the breakdown of transient atomic clusters. This process induces a notable reduction in the cluster size of the original system and a simultaneous increase in free volume. As a corollary, in the pure liquid phase, system viscosity undergoes a reduction with an escalating S content. However, the influence of further increments in S content on the system’s clusters and free volume gradually diminishes. Therefore, within the pure liquid phase domain, a continued increase in S content progressively mitigates its impact on viscosity.