Mechanical properties and microstructure of Ti5Si3 based composites prepared by combination of MASHS and SPS in Ti-Si-Ni and Ti-Si-Ni-C systems
Abstract Mechanical properties, synthesis behavior, microstructure and oxidation resistance of Ti 5 Si 3 -based composites prepared by combination of mechanically activated self-propagating high-temperature synthesis (MASHS) and spark plasma sintering (SPS) in Ti-Si-Ni and Ti-Si-Ni-C systems were investigated. Ti 5 Si 3 -Ti 2 Ni composite was synthesized in Ti-Si-Ni system while Ti 5 Si 3 -TiC-Ti 2 Ni was formed in the Ti-Si-Ni-C. Microstructural analyses showed that Ni and C extensively distributed in Ti 5 Si 3 phase and formed interstitial and substitutional solid solution titanium silicide. The activation energy values of 126 and 135 kJ/mol were calculated for initiation of combustion reaction in Ti-Si-Ni and Ti-Si-Ni-C systems, respectively. The isothermal oxidation behavior of the samples in air atmosphere was studied by TGA analysis and near the same oxidation resistance was detected. The fracture toughness of fabricated composites in Ti-Si-Ni and Ti-Si-Ni-C systems reached to 5 ± 0.1 and 6.1 ± 0.12 MPam 1/2 , respectively. The higher fracture toughness in Ti-Si-Ni-C system is related to the uniform distribution of TiC in the composite.