Diffusion Behavior Of Different Magnetic Component Under High Magnetic Fields

Diffusion of atoms is a main kind of transportation of substance. The microstructure and properties of material could be improved by controlling the diffusion of atoms. Various metallurgical phenomenon, such as solid phase transformation, recrystallization, grain boundary migration, are closely related with the diffusion of atoms. High magnetic fields affect these processes significantly. High magnetic fields can transfer high intensity magnetization energy to substances on the scale of atom or molecule, and change arrangement, matching and migration of atom and even change the thermodynamics state of the materials without any contact. Under high magnetic field conditions, materials will be affected by the strong magnetic force which is large enough even for non-ferrous magnetic materials. Therefore, the study on the diffusion under high magnetic field will make great contribution to found and complete the theory of material science under high magnetic fields. On the other hand, some metallurgical phenomena under high magnetic fields could be find answers or guides from such studies.By means of optical microscope, electronic microprobe analyzer, scanning electronic microscope etc, the solid diffusion behavior of Mg-Al and Cu-Co were researched under high magnetic fields. In the view of kinetics, we calculated the effective diffusion coefficient of Mg-Al from the examination on the thickness of diffusion layer and the distance of interface migration and Boltzmann-Matano plane solution method was used to calculate the interdiffusion coefficient of Cu-Co. And then in the view of thermodynamics, we also calculated the diffusion constant and diffusion activation energy of Mg-Al under high magnetic field.The research of Mg-Al diffusion couple under high magnetic fields showed that two intermetallics compounds (y, P) formed at the interface. The diffusion layer thickened and the exponential relationship between the thickness of diffusion layer and time matched under high magnetic fields. Whatever the magnetic field existed or not, the growth of γ and β layers were controlled by the volume diffusion. High magnetic field could increase the effective diffusion coefficient D by increasing diffusion activation energy Q, and the promoted the growth of Mg-Al diffusion layer.The research of Cu-Co diffusion couple under high magnetic fields showed that when the diffusion couples annealing at different temperatures, the diffusion distance was increased with the increasing temperature. The diffusion layer thickness changes with high magnetic fields. High uniform magnetic fields could promote the interdiffusion coefficient in copper substrate and inhibit it in cobalt substrate, which means that high uniform magnetic fields could promote the interdiffusion of atoms in copper substrate and inhibit it in cobalt substrate.