Effect of Cerium Oxide on Wear and Corrosion Behavior of Al5083/CeO2 Surface Composite Fabricated by Friction Stir Processing

In the present study, friction stir processing (FSP) was utilized to fabricate an Al5083/CeO2 surface composite by incorporating the nanosized cerium oxide particles into the matrix of Al5083 base alloy. Microstructural features, hardness and dry sliding wear were examined. In addition, the corrosion behavior of the base alloy, FSPed base alloy and the FSPed surface composite were studied and compared with each other. Optical and scanning electron microscopes were used for microstructural examinations. The corrosion resistance of the samples was examined by potentiodynamic polarization tests and was assessed in term of pitting potential and passivation range. The dry wear tests were conducted with a pin-on-disk tribometer at room temperature. Microstructural examinations revealed a uniform distribution of the reinforcement particles inside the stirred zone (SZ). The FSPed surface composite showed higher hardness and wear resistance in comparison to the base alloy. The dominant wear mechanisms for the FSPed and the FSPed composite specimens were adhesive and abrasive wear, respectively. The presence of CeO2 nano-particles in the SZ was caused a significant improvement in the pitting resistance, i.e. long passivation range and 95 percent reduction in the corrosion current density compared with the base alloy. The results indicated that incorporation of the cerium oxide into the surface of the Al5083 alloy enhanced the dry sliding wear as well as the pitting resistance of the alloy simultaneously.