Influence of W-doped concentration on the structural stability, elastic properties, hardness and brittle-or-ductile behavior of ZrB2 high-temperature ceramics

Abstract

To improve the mechanical properties of ZrB2 ceramics, the influence of W-doping on the structural stability, elastic properties, hardness and brittle-or-ductile behavior of ZrB2 is studied by the first-principles calculations. Three W-doped concentration are considered. The result shows that although W-doped ZrB2 exhibits both thermodynamic and dynamical stability, the structural stability of W-doped ZrB2 becomes weak with increasing W-doping concentration, particularly showing a reduction in dynamical stability. Furthermore, the W-doping can enhance the volume deformation resistance of ZrB2, while it reduces the shear deformation resistance and Vickers hardness of ZrB2. In particular, the W-doping results in the trends of brittle-to-ductile transition for ZrB2 ceramics. Essentially, the improvement of brittle-to-ductile transition is that the introduction of W-doping weakens the electronic interaction between B and B atoms along the shear direction. Therefore, we believe that the metal W is a useful element to improve the mechanical properties of ZrB2 high-temperature ceramics.