Mass transport driving forces under electric current in the liquid Sn-Zn system

TL;DR

This paper investigates how electric currents influence mass transport in liquid Sn-Zn alloys, revealing that magnetic forces, rather than electrostatic ones, primarily drive the process under high current densities, clarifying mechanisms in the field.

Contribution

The study demonstrates that in liquid Sn-Zn systems, magnetic forces dominate mass transport under electric currents, distinguishing magnetoconvection from electroconvection and resolving literature confusion.

Findings

Magnetic forces drive mass transport at high current densities.

Electroconvection and magnetoconvection mechanisms are distinguishable.

Magnetoconvection is the primary mechanism in the studied system.

Abstract

Significant effects of electric currents on mass transport in liquid metals have been observed for long, but the origin of the corresponding driving forces remains unclear in the literature. Without current, two driving forces induce mass transport in liquid metals. (i) A chemical force, coming from concentration gradients. In that case, mass transport occurs by diffusion. (ii) A physical force, resulting from density gradients thermally and/or chemically induced. Here, mass transport occurs by thermal and/or solutal convection. Under electric currents, these driving forces are modified, either by electrostatic or magnetic forces, the corresponding mechanisms being referred to as electroconvection and magnetoconvection, respectively. However, these mechanisms cannot easily be distinguished from each other, leading to confusion in literature. Here, it has been shown that, in the liquid Sn-Zn system, the driving force induced by 500-1000 A/cm 2 electric current densities is magnetic rather than electrostatic, the mechanism being therefore magnetoconvection.