Structural Modification and Electromagnetic Response of Ball-Milled Nd-Fe-C Alloys

With the rapid development of communication technologies, electromagnetic pollution has become increasingly serious, driving the urgent demand for high-performance low-frequency microwave absorbers. This work focuses on Nd-Fe-C powders prepared by high-energy ball milling, aiming to explore low-cost, mass-producible absorbing materials with excellent low-frequency microwave absorption performance. The Nd10.2Fe84.6C5.2 alloy was synthesized via arc melting, and its powders were subsequently fabricated by high-energy ball milling for different milling durations. X-ray diffraction, scanning electron microscopy, and vector network analysis were employed to investigate the effect of high-energy ball milling on the microwave absorption properties of the Nd10.2Fe84.6C5.2 alloy. As the ball milling time increased, the particle size decreased, and the minimum reflection loss shifted to a lower frequency. Additionally, increasing the thickness of the absorbing coating also moved the minimum reflection loss toward the low-frequency region. The Nd10.2Fe84.6C5.2 alloy after 12 h of ball milling had good performance in the C (4.0–8.0 GHz) band when the coating thickness was in the range from 1.4 to 2.2 mm. A minimum reflection loss of −19.2 dB was achieved at 5.2 GHz, and the effective absorption bandwidth (RL < −10 dB, corresponding to a microwave absorption efficiency of 90%) reached 1.8 GHz at a matching thickness of 2.2 mm.