Abstract
The practical applications of ZrC are restricted by its low fracture toughness and resistance to sintering densification. This study reports the in-situ precipitation behavior of (Zr,W)C solid solution precipitates induced by Ti. The (Zr 0.7 W 0.3 )C solid solution powder was prepared via carbothermic reduction using pressureless sintering at 2200 °C for 1 h. Varying quantities of TiH 2 were reacted with the (Zr 0.7 W 0.3 )C matrix, to precipitate the second phase in-situ, via hot-pressing sintering (50 MPa) at 1600 °C for 1 h. When the content of TiH 2 was 10 mol%, W and W 2 C were the second phases precipitated. As the TiH 2 concentration increased, the precipitates converted into W 2 C and the (Ti,Zr)C solid solution. Furthermore, nano-scale dot-like W precipitates gradually increased inside the crystal grains of the (Zr,W,Ti)C matrix. The optimized comprehensive mechanical properties of (Zr,W,Ti)C-based multiphase ceramics were obtained by adding 40 mol% TiH 2 ; the relative density was 99.7%, the Vickers hardness was 24.68 GPa, and the fracture toughness was 5.76 MPa·m 1/2 . The precipitates (of varying type and concentration) exhibited distinct toughening effects relative to the (Zr,W)C solid solution. • TiH 2 significantly promoted the densification process of (Zr,W)C, and the grain size was refined from 65 to 0.84 μm. • As the Ti content increased, nano-scale point-like W precipitates appeared in the crystals of the (Zr,W,Ti)C matrix. • The prepared (Zr,W,Ti)C multiphase ceramic exhibits high hardness (24.68 GPa) and high fracture toughness (5.76 MPa·m 1/2 ).
Published Version
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