Preparation and Microwave Absorption Properties of Melt-Spun Nd2Co17 Alloys with Different Post-Treatment Processes

Nd2Co17 alloy particles were prepared by melt-spinning and high-energy ball-milling techniques. Vacuum heat treatment or crushing was added during the fabrication period to obtain absorbing powders. The microstructure and electromagnetic properties of the absorbing powders were studied. The electromagnetic parameters were investigated using an Agilent vector network analyzer. The size and thickness of the crushed alloy powders was distinctly decreased compared with that of the uncrushed sample. The reduced size and thickness of alloy powers can significantly enhance electromagnetic matching for absorbing powders. Consequently, the microwave absorption properties of the crushed alloys were significantly improved. The reflection loss (RL), which is based on transmission line theory, shows that the vacuum heat treatment sample had an RL peak in the C-band. However, the crushed sample had an RL peak between the C-band and the X-band. The minimum RL value of −8.1 dB was obtained at 8.2 GHz for the crushed Nd2Co17 alloy, and the absorption bandwidth at less than −5 dB reached 9.4 GHz. In contrast, the RL peak of the Nd2Co17 alloys without post-treatment was located in the S-band. These results prove that proper post-treatment is the key to regulating electromagnetic matching, whereby optimal microwave absorption properties of the alloys can be obtained in different bands.