Particle refinement of ZrB 2 by the combination of borothermal reduction and solid solution

Flexible synthesis of ultra‐fine ZrB 2 powders was achieved by borothermal reduction in a mixture of ZrO 2 , boron, and TiO 2 . Without TiO 2 additive, coarse ZrB 2 powders with particle size of 0.81 μm were obtained, presumably due to good wettability and solubility of ZrB 2 in the byproduct B 2 O 3 . It was found that the particle growth of ZrB 2 was effectively inhibited by the solid solution of TiB 2 (≥1 mol%). The refinement mechanism was that the solid solution of in situ formed TiB 2 presumably lowered the wettability and solubility of ZrB 2 in the B 2 O 3 liquid and significantly inhibited the coarsening of ZrB 2 . The average particle size of resulting powders decreased to 0.37 μm with the addition of 10 mol% TiO 2 .