Synthesis of high‐purity high‐entropy metal diboride powders by boro/carbothermal reduction

Synthesis of high‐purity high‐entropy metal diboride powders is critical to implementing their extensive applications. However, the related studies are rarely reported. Herein we first theoretically studied the synthesis possibility of high‐purity high‐entropy diboride powders, namely (Hf 0.25 Ta 0.25 Nb 0.25 Ti 0.25 )B 2 (HTNTB), via boro/carbothermal reduction by analyzing the thermodynamics of the possible chemical reactions and then successfully synthesized the high‐purity and superfine HTNTB powders via boro/carbothermal reduction for the first time. The as‐prepared powders exhibited low‐oxygen impurity content of 0.49 wt% and small average particle size of 260 nm. Meanwhile, they possessed good single‐crystal hexagonal structure of metal diborides and high‐compositional uniformity from nanoscale to microscale. This work will open up a new research field on the synthesis of high‐purity high‐entropy metal diboride powders.