Effect of Simultaneous Use of Silica Nanoparticles and Heat Treatment on High-Cycle Bending Fatigue Lifetime in Piston Aluminum Alloy

Aluminum-silicon alloys have vast applications in-vehicle components, such as the piston. Usually, such parts are under thermal and mechanical cyclic loadings, and therefore, they should have enough fatigue strength. For strengthening methods, the heat treatment and the addition of nanoparticles could be mentioned. In this research, the effect of the simultaneous use from SiO2 nanoparticles and the heat treatment was investigated on the high-cycle fatigue lifetime of the piston alloy, which is the novelty of this study. The stir-casting method was used for adding nanoparticles into the aluminum matrix, and the T6 heat treatment was done on samples. The microstructure was examined by the optical microscopy and also the field-emission scanning electron microscopy (FESEM), and high-cycle bending fatigue tests were performed, under fully-reversed loading conditions. Based on FESEM images, no agglomeration of nanoparticles was observed in the matrix. In addition, it was found that using SiO2 nanoparticles, heat treatment, and the combination of two approaches, caused to the improvement of the fatigue lifetime, for 304, 411 and 237%, respectively. According to high-cycle bending fatigue data, the fatigue strength coefficient of the piston alloy increased by the heat treatment, and the addition of nanoparticles.