Dual plate-like grains of (Ti, Zr)B2 and W2B5 toughened solid solution composites fabricated via in-situ reaction spark plasma sintering of (Ti, W)C and ZrB2 powders

Abstract

Novel dual plate-like grains of (Ti, Zr)B2 and W2B5 toughened solid solution composites were fabricated by the in-situ reaction spark plasma sintering at 1800 °C using (Ti, W)C and ZrB2 powders. The composites were predominated and composed of the (Zr, Ti, W)C solid solutions and plate-like (Ti, Zr)B2. In the (Ti, W)C-ZrB2 reaction system, W promotes the anisotropic growth of (Ti, Zr)B2 grains, while Ti makes the formation reactions of WxBy thermodynamically feasible. When the addition of ZrB2 exceeds 40 mol%, W begins to be boronized into WxBy which is mainly composed of plate-like W2B5. The (Ti, W)C-50 mol% ZrB2 composite with dual plate-like grains of (Ti, Zr)B2 and W2B5 exhibited the best comprehensive mechanical properties of hardness of 26.5 GPa, flexural strength of 620 MPa, and fracture toughness of 6.6 MPa·m1/2, which provide a new approach for the enhanced toughness without the introducing of metal impurities.