Thermal stability and tensile properties of sol-enhanced nanostructured Ni–TiO2 composites

A highly-dispersed TiO2 nano-particles reinforced Ni–TiO2 composite was prepared by sol-enhanced composite electroplating. The microstructure, thermal stability and tensile properties of the sol-enhanced and traditional Ni–TiO2 composites were explicitly compared. TiO2 nano-particles agglomerated to large clusters of ∼400 nm in the traditional Ni–TiO2 composite. In contrast, nano-sized TiO2 particles (∼15 nm) were distributed at grain boundaries in the sol-enhanced composite. The grain size, higher micro-strain (∼0.31%) and higher microhardness (∼407 HV50) of the sol-enhanced Ni–TiO2 composite were stabilized up to 250 °C compared to 150 °C of the traditional composite. The sol-enhanced Ni–TiO2 composite showed a much higher tensile strength of ∼1050 MPa compared to ∼610 MPa of the traditional composite. The lattice diffusion dominated at high temperatures during grain growth for the sol-enhanced composite. The distribution and location of TiO2 nano-particles played a significant role in determining the thermal stability and tensile behaviors.