Preparation and microwave absorption properties of NdFeB alloys

In order to improve the microwave absorbing properties of NdFeB alloys, as-jet milled powders were further processed in a planetary mill. The phase structure, morphology and particle size of the alloy powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser diffraction-based particle size analyzer, respectively. The saturation magnetization and electromagnetic parameters of the powders were determined by a vibrating sample magnetometer (VSM) and a vector network analyzer (VNA), respectively. The results showed that the saturation magnetization decreased as the milling time increased. The minimum absorption peak frequency shifted towards the lower region and the reflection loss values increased with increasing the ball milling time. The minimum absorption peak value of the powders milled for 15 h on the basis of jet milling reached −44.4 dB at 11.04 GHz, and the bandwidth of R<-10 dB was 1.2 GHz with the best matching thickness of 1.8 mm.

Reflection loss of the NdFeB powderFigure optionsDownload as PowerPoint slide