Effect of Y_2O_3 particles on corrosive wear of aluminum made using an arc melting process

摘要

Aluminum is one of the most attractive metals, which has found many engineering applications due to its great formability, low density, and high resistance to corrosion. Since aluminum is not strong, it is usually strengthened by introduction of second phases, reinforcing particles or fibers. However, when second phases reinforcing particles or fibers are introduced, the corrosion resistance of aluminum may decrease due to the formation of microelectrodes that accelerate electrochemical reactions. Such decrease in corrosion resistance negatively influences industrial application of aluminum-based materials. The objective of this work was to strengthen aluminum without decreasing its corrosion resistance. Yttria was selected as a reinforcing phase to make yttria-aluminum composites using an arc melting process. It was demonstrated that by adding yttria particles, the modified aluminum exhibited higher hardness, improved polarization behavior and higher resistance to corrosive wear in a sulfuric acid solution. Microstructural examination showed that the microstructure of aluminum became finer when yttria powder was added. However, the added yttria particles were not observed in the modified aluminum. Instead, a new phase, Al_3Y, had formed, which could result from possible decomposition or melting of the yttria particles during the arc melting process. The improved properties of aluminum by yttria addition could thus be attributed to the formation of Al_3Y phase and the resultant finer microstructure.