Influence of TiO 2 nanoparticle dispersion on mechanical behavior of T6-treated Al7075 composites
Angadi Seshappa, N. Srinivasa Reddy, K. Hema Latha, Devunuri Suresh, P.S.V. Ramana Rao, Rajesh Kumar, Panthangi Ravi Kumar, Venkata Naga SrinivasaRao RepalleAbstract
High specific strength and attractive mechanical properties have resulted in significant interest in aluminium matrix nanocomposites for lightweight structural applications. In this work, Al7075/TiO 2 nanocomposite containing 0.5, 1.0, 1.5 and 2.0 wt.% TiO 2 nanoparticles with a mean particle size of 30 nm were prepared by ultrasonic-assisted stir casting followed by T6 heat treatment. The effect of TiO 2 content on density, porosity, microstructure, hardness and tensile properties is investigated. The prepared nanocomposites were characterised by optical microscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The theoretical density increased from 2.810 to 2.839 g/cm 3 with increasing TiO 2 content, while the calculated porosity increased from 0.64 % for the unreinforced Al7075 alloy to 1.66 % for the 2.0 wt.% TiO 2 composite. The maximum yield strength, ultimate tensile strength, and hardness of T6-treated Al7075/0.5 wt.% TiO 2 nanocomposite were 152.45 MPa, 198.23 MPa, and 84.59 BHN, respectively. These values represent improvements of about 5.87 %, 10.74 % and 24.4 %, respectively as compared with the T6-treated Al7075 base alloy. Further increase in TiO 2 content resulted in gradual decrease in hardness and tensile properties, due largely to increase in porosity, clustering of nanoparticles and non-uniform particle distribution. Among the investigated compositions, the addition of 0.5 wt.% TiO 2 showed the best combination of microstructural features and mechanical properties. The results demonstrate that the TiO 2 content should be controlled to minimize casting defects and maximise the strengthening response of the T6-treated Al7075/TiO 2 nanocomposites.