Novel Ti3SiC2-(Ti, Zr)B2 toughened (Ti, Zr)C-based composites with enhanced mechanical properties fabricated by dual in situ reactions hot-pressing at low temperature

The fully dense Ti 3 SiC 2 -(Ti, Zr)B 2 toughened (Ti, Zr)C-based composites were fabricated at 1400-1600 degrees C for the first time by dual in situ reactions hot -pressing with TiC, ZrB 2 , and Si as the initial powders. The influence of ZrB 2 , Si content and sintering temperature on the microstructure and mechanical properties of the composite was reported. When 10 mol% ZrB 2 was added, Si combined with residual TiC to form Ti 3 SiC 2 and SiC. However, with the addition of ZrB 2 increase to 20 mol% and 30 mol%, Si participated in the formation of ZrSi and was not enough to react with TiC to form Ti 3 SiC 2 . The low -temperature in situ reactions, multiphase coupling effects, and the pinning effect of nano-SiC refine the microstructure of the composites. There are specific crystal orientation relationships between (Zr, Ti)C and (Ti, Zr)B 2 , as well as between (Ti, Zr)C and SiC. The layered Ti 3 SiC 2 and plate -like (Ti, Zr)B 2 by dual in situ reactions effectively improve the fracture toughness of the composites. The 10 ZB-15 possesses a highest fracture toughness of 6.1 MPa center dot m 1/2 . The 30 ZB-16 has the good comprehensive mechanical properties. The fracture toughness, flexural strength, and hardness of 30 ZB-16 is 5.6 MPa center dot m 1/2 , 679 MPa, and 26.4 GPa, respectively. The Ti 3 SiC 2 and TiB 2 formed during dual in situ reactions enables the composite to exhibit excellent oxidation resistance and wear resistance.