Fig. 4 shows the propagation of crack in the polished surface of SiC/(Mo, W)Si2 composite. With the existence of SiC particles and whiskers in (Mo, W)Si2 matrix, clear deflection of crack by tilting and twisting around SiC is observed. The deflection of crack would lead to the increase of fracture toughness. And it is also observed in Fig. 4 that the whiskers bridge the crack. Consequently, the traction force of bridging whiskers could efficiently stop the propagation of crack and increase the fracture toughness.