Superhard single‐phase (Ti,Cr)B2 ceramics

Abstract A nominally pure and dense (Ti 0.9 Cr 0.1 )B 2 ceramic was produced by spark plasma sintering of powders synthesized by boro/carbothermal reduction of oxides. The synthesized powders were a single phase and had an average particle of 0.4 ± 0.1 μm and an oxygen content of 1.2 wt%. Average Vickers hardness values of the resulting ceramics increased from 25.9 ± 0.8 GPa at a load of 9.81 N, to 46.3 ± 0.8 GPa at a load of 0.49 N. Compared to the nominally pure TiB 2 ceramic obtained under the same processing conditions, the (Ti 0.9 Cr 0.1 )B 2 ceramic had higher values under the same load due to the finer average grain size (2.4 ± 1.0 μm), higher relative density, and solid solution hardening. The results indicated that the Cr addition promoted densification, suppressed grain growth, and improved the hardness of TiB 2 ceramics. This is the first report for dense and single‐phase (Ti,Cr)B 2 ceramics as superhard materials.