A New Method to Improve the High-Temperature Mechanical Properties of Ti3SiC2 by Substituting Ti with Zr, Hf, or Nb

Ti3SiC2 shows a unique combination of the properties of both metals and ceramics. However, its stiffness and strength lose rapidly above 1050 degrees C, which is the main obstacle for the high-temperature application of this material. To improve the high-temperature mechanical properties of Ti3SiC2, Zr, Hf, or Nb were used as dopants in Ti-3(SiAl)C-2. At room temperature, the Zr-, Hf-, or Nb-doped Ti-3(SiAl)C-2 ceramics have comparable stiffness, hardness, strength, and fracture toughness with those of Ti-3(SiAl)C-2. At high temperatures, however, a significant improvement in stiffness and strength has been achieved for (Ti1-xTx)(3)(SiAl)C-2 (T=Zr, Hf, or Nb). (Ti1-xTx)(3)(SiAl)C-2 can retain high degrees of stiffness and strength up to 1200 degrees C, which is 150 degrees C higher than those for Ti-3(SiAl)C-2.