Nickel-aluminum-bronze/Al2O3 surface nanocomposite produced by friction-stir processing: Corrosion properties and microstructure

摘要

In this research, friction stir processing (FSP) was applied for fabricating nanosized particles of Al2O3 as a surface composite layer on nickel-aluminum bronze alloy. In addition, the effect of nanosized Al2O3 on the microstructure, hardness, and corrosion resistance of the alloy surface was investigated. To study the microstructure of the FSP treated surface, optical and scanning electron microscopy were used. Moreover, the static immersion and electrochemically corrosion tests were employed to investigate the corrosion resistance of the FSP-treated surface. The results indicated that using nanoparticles of Al2O3 to produce the surface nanocomposite layer led to fewer amounts of beta transformation products. Furthermore, dynamic re-crystallized sub-grains were formed in a grains in the stir zone during severe plastic deformation. In addition, a significant improvement in the corrosion resistance of the alloy surface was observed in the friction stir processed nanocomposite sample in comparison to the one without nanoparticles.