Low‐temperature synthesis of high‐entropy (Hf 0.2 Ti 0.2 Mo 0.2 Ta 0.2 Nb 0.2 )B 2 powders combined with theoretical forecast of its elastic and thermal properties

Abstract A theoretical calculation combined with experiment was used to study high‐entropy (Hf 0.2 Ti 0.2 Mo 0.2 Ta 0.2 Nb 0.2 )B 2 (HEB‐HfTiMoTaNb). The theoretical calculation suggested HEB‐HfTiMoTaNb could be stable over a wide temperature range. Then, a novel solvothermal/molten salt‐assisted borothermal reduction method was proposed to efficiently pre‐disperse transitional metal atoms in a precursor and synthesize (Hf 0.2 Ti 0.2 Mo 0.2 Ta 0.2 Nb 0.2 )B 2 nanoscale powders at 1573 K for 6 h, which is nearly 300 K lower than previous reports. The characterization results indicated that the as‐synthesized nanoscale HEB‐HfTiMoTaNb powder was hexagonal single‐phase with homogeneous elements distribution and uniform size, and the oxygen content of the particles is 0.97 wt%. Simultaneously, the mechanical properties, anisotropic nature, and thermal properties of HEB‐HfTiMoTaNb were investigated by density functional theory (DFT) calculations. The Cannikin's law was adopted to explain the improvement of comprehensive mechanical properties. In addition, a significant reduction of thermal conductivity was observed for HEB‐HfTiMoTaNb and it only was 1/15 of the value of HfB 2 . This work suggests a reliable technique for synthesis of nanosized HEB powders and discovery of high‐entropy materials under the guidance of first‐principle theory.