The Effect of Nickel on the Viscosity of Iron-Based Multicomponent Melts

Abstract

In this work, we investigated the temperature dependence of the kinematic viscosity of multicomponent Fe72.5−xNixCu1Nb2Mo1.5Si14B9 melts with a Ni content of up to 12.7 at. %. The peculiarities of the temperature dependence of Ni-containing melts were explained by the tendency of Ni atoms to surface segregation. Ni atoms are concentrated near the interfaces of the liquid and solid phases in the mushy zone at the stage of melting and restrain the melting of the solid phase. With increasing Ni content, the Arrhenius type of viscous flow begins at a higher temperature. Ni atoms are concentrated at the periphery of clusters, increasing their size and decreasing their mobility. The movement of Ni-containing clusters increases the activation energy and decreases the kinematic viscosity. The change in the activation energy at a temperature of about 1700 K was associated with a liquid-liquid structure transition (LLST). This structural transition is reversible since it is observed both at the heating and cooling stages. The increase in kinematic viscosity at temperatures above 1900 K was associated with the decomposition of high-temperature clusters based on cementite and silicon oxides.

Melting, Solidification, and Viscosity Properties of Multicomponent Fe-Cu-Nb-Mo-Si-B Alloys with Low Aluminum Addition

“…Anomalies in fluid flow manifest themselves in changes in the activation energy of viscous flow during the transition from a low-temperature region to a high temperature and vice versa. Moreover, the activation energy increases with the increasing size of clusters participating in the viscous flow of the melt [13].…”

Rheological Characteristics of Fe–C–Cr(Ni) Alloys

“…Nickel was found to decrease viscosity within this range, which was related to the change in the primary solidification structure from a body-centered cubic unit cell to a face-centered cubic unit cell [ 27 ]. The effect of nickel on the viscosity of Fe-based multicomponent melts was evaluated in [ 28 ], where nickel decreased the viscosity and increased the activation energy, with the change in viscosity being related to structural changes and decomposition of high-temperature clusters of cementite and silicon oxides. A large amount of published data on the viscosity of metals, alloys, and intermetallic compounds is given in [ 19 ].…”