Microwave Plasma Synthesis of MoNbTaVW High Entropy Alloy: A Novel Approach

We investigate a novel approach for synthesis of the high entropy alloy MoNbTaVW from metal oxide precursors via microwave-induced plasma. The process involves ball milling of the metal-oxides, followed by microwave plasma annealing at 1800°C for a duration of 1 hour. Hydrogen is used as the plasma feedgas for efficient reduction of metal-oxides. Analysis through X-ray diffraction, scanning electron microscopy/energy dispersive x-ray analysis, and Vickers hardness testing has revealed the characteristic structure/properties of high-entropy alloy. This includes a single-phase body-centered cubic structure with a uniform distribution of all five metals, and measured hardness of 6.8 ± 0.9 GPa. This hardness aligns closely with findings reported in literature for high entropy alloys sharing the same five-metal configuration. In addition to rapid volumetric heating enabled by interaction of microwaves with the dielectric precursors, the microstructure exhibits clear evidence of localized microwave sintering. The outcomes highlight the promising potential of microwave plasma as a rapid, cost-effective, and versatile processing tool for the production of high entropy alloys.