Synthesis and electromagnetic wave absorbing properties of high-entropy metal diboride-silicon carbide composite powders.

Pure and fine high-entropy metal diboride-silicon carbide composite powders, namely (V,Ti,Ta,Nb)B2-SiC (HEB-S), were successfully synthesized via a facile high-energy ball milling-assisted boro/carbothermal reduction method at 1600 °C. The as-prepared HEB-S powders exhibited low‐oxygen impurity content of 0.36 wt%; (V,Ti,Ta,Nb)B2 powders had a single-crystalline hexagonal structure of metal diborides and simultaneously possessed high compositional uniformity. Short rod-like SiC particles were well distributed in the (V,Ti,Ta,Nb)B2 matrix. The formation mechanisms were well interpreted by analyzing the thermodynamics of the possible chemical reactions. The electromagnetic wave (EMW) absorption of the HEB-S powders was studied by a vector network analyzer. The HEB-S powders displayed a minimum reflection loss of − 44.9 dB at the thickness of 4.4 mm and the effective absorption bandwidth of 1.28 GHz at 4.0 mm thickness (Minimum RL was − 29.4 dB). This work will open up a new way to synthesize high-entropy metal diboride composite powders, and the obtained powders are expected to play an important role in the EMW absorption applications. [ABSTRACT FROM AUTHOR]