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Material Migration in Sintered NdFeB

      The above changes depend on the sintering stage, the temperature, the particle size of the powder, and the material composition. Although the above process is not easily observed, it does exist. This phenomenon was observed when the author observed the sintered magnet film using a JEM-1000kV ultrahigh-voltage electron microscope.

      There are two types of material migration mechanisms in the sintering process. The migration of substances caused by the flow of substances on the surface of the particles is called the surface migration of the sintered materials, such as surface diffusion and evaporation-agglomeration. The two types of arsenic are shown in Figure 8-2. Fig. 8-Z's Shangshangfenyi's erroneously-swept note 7 Heart Assemblage, the right part shows the schematic diagram of evaporation-coagulation, surface diffusion and volume diffusion. The lower part is the intention of volume migration, and the right part shows grain boundary diffusion and plastic flow path. Diagram has been deleted.

Surface diffusion and evaporation-agglomeration are the two most important components in controlling the surface migration of sintered materials. The volume diffusion from the surface source to the surface well is possible. The volumetric migration of the material during sintering can cause a change in the basic size of the sintered body. Most of the volume migration process of the material is in the final stage of sintering. Volume diffusion, grain boundary diffusion, viscous flow, and plastic flow are all within the scope of the volumetric migration mechanism of matter. The importance of the sintering mechanism can be seen from the material, powdery degree, sintering stage, sintering temperature, and other process parameters.