Mechanical and Electrical Characteristics of WB₂ Synthesized at High Pressure and High Temperature

Single-phase tungsten diboride (WB₂) was synthesized at high pressure and high temperature. The different grain sizes ranging from 300 nm to 3 µm were successfully obtained in WB₂ by controlling the experimental conditions. The effects of grain size on hardness and resistivity properties were investigated. The Vickers hardness of WB₂ was modulated with grain size. The maximum asymptotic Vickers hardness is 25.5 GPa for WB₂ with a grain size of 300 nm which is a 10% increase compared to WB₂ with a grain size of 3 µm. The optimal electrical resistivity of WB₂ was 10^-7 Ωm with the biggest grain size of 3 µm, which is ascribed to low grain boundary density. The superior properties of hardness and electrical resistivity demonstrate that WB₂ should be a new functional hard material replacing WC which is widely used in industrial production.