The High Magnetic-Field-Induced Thermodynamic Mechnism in the Interface between the Carbides and Martrix in Steel

Abstract

The physical mechanism of the magnetic field-induced phase transition for M23C6/α-Fe was investigated utilizing a combination of high-resolution transmission electron microscopy (HRTEM) with Micromagnetic theory. The HRTEM results revealed that the M23C6/α-Fe interface exhibited a specific magnetic field-induced phase transition under the action of a high-temperature magnetic field, which increased the interface thickness between the carbide and matrix. Micromagnetic modeling establishes the relationship between the boundary thickness and the external magnetic field. The magnetization curves of carbide and matrix under high magnetic field are significantly shifted toward high temperature, which contributes to the reduction of the magnetic structure difference between M23C6 and α-Fe. The application of a strong magnetic field has a notable effect on the magnetization curve, shifting it towards higher temperatures. This diminishes the discrepancy in magnetic structure between M23C6 and α-Fe, leading to a substantial reduction in magnetostatic energy while concurrently augmenting magnetic exchange energy. Consequently, this process results in an increased thickness of the boundary between M23C6 and α-Fe. Combination of experiment and theory verifies the physical mechanism of the phase transition of carbides by magnetic field to provide a new theoretical basis for the formation of carbides by magnetic field.

Keywords: High magnetic field, Phase transformation, Interface, Thermodynamic mechanism