Novel Microwave Plasma Synthesis of High Entropy Borides

This research focuses on the benefits of microwave-induced plasma as a means to synthesize high entropy transition metal borides. This synthesis route allows rapid heating/cooling rates and investigation into potential heating mechanisms and reaction pathways offered by MW-plasma. The microwave plasma approach relies on metal oxide thermal reduction (borothermal or boro/carbothermal) for precursor powders containing metal oxides with graphite, boron, and B₄C as reducing agents. This precursor powder mixture allows efficient microwave energy absorption contributing to rapid and uniform sample heating. The results show that boro/carbothermal reduction coupled with MW-plasma results in higher measured hardness compared to previous studies and when compared to the borothermal reduction approach. The potential interactions of the low-temperature microwave plasma with the precursor powder will be discussed in the context of metal oxide thermal reduction methods and mechanical properties.