The tensile test results show that the addition of nano TiO2 particles to Al matrix composites increases the tensile strength
of the alloy at room temperature along with an increase in the TiO2 particles’ volume fraction from 0.5 to 4.5 vol.%. The
measured maximum and minimum tensile strength of the composite samples were 250 and 198 MPa respectively. Great
enhancement in tensile strength was observed due to the low degree of porosity and the good distribution of Nano ceramic particulates. The low degree of porosity results from using powder metallurgy route, which leads to uniform distribution of TiO2 particles and lower air gaps between grains. The strong multi-directional grain refinement and thermal stress in the aluminum/TiO2 interface are also important factors; they play a great role in improving the strength of the composites. The grain refined strengthening effect of the TiO2 particles, this is due to they act as the heterogeneous nucleation catalyst for the matrix which is improved with the increases in volume fraction. According to the experimental
results, a significant enhancement in strength is noted initially when the Nano particulate is added; however, the further
increase in the amount of TiO2 nanoparticles leads to a reduction in strength values. The weakening factors of the
mechanical properties might be the reason for this including the porosity (Fig. 5) and the particle clusters (see Fig. 6)