Mechanisms of producing anisotropy in NdFeB material during HDDR process

The microstructure, magnetic property and anisotropic mechanism of NdFeB as-cast powder and the material in different HDDR treatment stages were investigated. It is found that the anisotropy of NdFeB as-cast powder is greater than that of HDDR NdFeB materiacs. The anisotropy of HDDR NdFeB material decreases monotonously and finally disappears with the disproportionation time prolonging, which means that the anisotropy of HDDR NdFeB material originates from as-cast texture. Short disproportionation time is helpful for the anisotropy attainment. As an anisotropy passing medium, the disproportionation lamella microstructure transfers the anisotropy of as-cast powder to the final HDDR NdFeB material by means of crystallographic orientation.