Creep Properties in TiO₂ Nanoparticle Reinforced Aluminum Matrix Composites

Creep behaviors of the aluminum composites containing 3 vol% of TiO₂ nanoparticles (15 nm in size) are studied at 523 K. In the high stress region, the composites show enhanced creep resistance exhibiting high value of the apparent stress exponent and the high threshold stress, which is determined to be 162 MPa. The true stress exponent of minimum creep strain rate is found to be 5 implying the creep is controlled by lattice diffusion. Negligible stress dependence in the creep rate is found when the applied stresses are <200 MPa, since the creep behavior depends dominantly on the diffusional flows of the matrix that are strictly limited by the nanoparticles.