Effect of Antimony on the Reaction of Hafnium Diboride with Iridium

Ternary borides of iridium and hafnium were prepared by a facile method by reacting iridium with hafnium diboride in the presence of metallic antimony at 1500°С. The product is comprised of elongated Hf 2 Ir 5 B 2 crystals and grains up to 10–15 µm in size consisting of other Hf–Ir–B ternary borides. Antimony addition to the reaction mixture changes the reaction scheme and yields compounds that do not melt in the range 1000–1300°С, thereby helping to produce a free-flowing product. The nascent IrSb 2 decomposes at 1500°С; the released iridium is consumed in the production of ternary borides, while the antimony evaporates and can be completely removed from the reaction zone. The high evaporation rate of antimony prevents the consolidation of ternary boride particles, and ensures the formation of a free-flowing product. The proposed strategy can be used to produce Hf–Ir–B ternary boride powders for use in various materials science fields.