Abstract:The nano-SiO2 particle reinforced NiTi matrix composites (SiO2%=1%~4%, mass fraction) were fabricated by Spark Plasma Sintering (SPS) method, and the effects of the contents of SiO2 nano-particles on the microstructure, the phase transformation points, the mechanical properties and the fracture feature were investigated. The results indicate that the microstructures of the composites mainly consist of the phases of B2-NiTi, B19'-NiTi, Ni3Ti, Ti2Ni and SiO2, and the SiO2 particles are evenly dispersed in NiTi matrix. The addition of SiO2 reduces the phase transformation point of Mf, As and Af, but has no strong influence on Ms. The SiO2 particles can obviously improve the strength of NiTi alloy, but with the increase of SiO2 particles, the fracture mode of the alloy changes from ductile fracture to brittle fracture. More over, the composites containing SiO2 exhibit higher deformation recovery and better superelasticity than that of NiTi alloy in the deformation within 6%