Effect of solid solution of Si on mechanical properties of TiAl3 based on the multi-laminated Ti-(SiCP/Al) composite system

In the present work, TiAl3 layers were synthesized by reaction annealing of a multi-laminated Ti-(SiCP/Al) composite at 650 °C. It was found that Si dissolved in the TiAl3 layers during annealing. The effect of Si in the TiAl3 layers on mechanical properties was investigated both by experiment and theory. The experimental results show that after annealing at 650 °C for 3 h, the solid solubility of Si in the TiAl3 layer is about 6 at%, which leads to the lattice distortion of TiAl3. Due to the solid solution of Si in TiAl3, the elastic modulus and nanohardness increased up to 280 Gpa and 10.7 Gpa, respectively. Furthermore, the mechanism of increased modulus due to the solid solution of Si is verified by first-principles calculation of the theoretical elastic properties and can be explained from the electronic structure: (i) a new hybridization between Si3s and Al3s; (ii) primarily covalent interactions along Al3Si bonds.