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In the present work, a nanograin layer of about 150 lm thick was formed on the surface of an interstitial-free (IF) steel via friction stir processing. Then, the fatigue and corrosion behaviors of IF steel with nanograin layer were compared with that of coarse-structure counterpart. More than threefold increase in the hardness was observed due to the formation of nanograin layer. The size of nanograins in the stir zone was within 30-150 nm. This resulted in 50% increase in the fatigue strength of nanostructured specimen. Furthermore, the fracture surfaces were characterized using field emission scanning electron microscopy and scanning electron microscopy. As for the fatigue behavior of nanograin IF steel, the fracture surface was characterized by the formation of nanospacing striations and nanodimples. Besides, the nanograin structure pronounced the passivity and exhibited higher corrosion resistance.

In this study, the effects of different concentrations of SiO 2 nanosized particles in the bath on de position rate, surface morphology and wear behavior of Ni-P-SiO 2 composite coatings were investigated. The rate of coating deposition was influenced by the incorporation of SiO 2 particles. The observations of microstructural morphology were performed with field emission scanning electron microscopy. The amount of deposited SiO 2 was examined by X ray energy dispersive analysis. The results showed that for the coating produced at 12.5 g/L of nanoparticles, the amount of co deposited SiO 2 nanoparticles and microhardness reached their maximal values 4.5 wt % and 453 VH, respectively. Furthermore, nanocomposite coating improved the wear resistance of the aluminum substrate.

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