Effect of Oxygen on Phase Evolution in Al-Y2O3 Nanocomposites by Mechanical Alloying

To investigate the effect of the oxygen amount involved in mechanical alloying (MA) of Al and Y 2 O 3 powders on the phase evolution of the alloy powders, two types of MA were performed: MA with low and high oxygen content in the MA atmosphere. Analyses of the lattice parameter and composition of the Al matrix by X-ray diffraction and scanning electron microscopy with energy dispersive X-ray spectroscopy, respectively, and the integrated intensity of Y 2 O 3 indicated that in the low-oxygen MA, the driving force for Y 2 O 3 precipitation was small and Y and O dissolved into the matrix, producing supersaturated solid solution powder, while in the high-oxygen MA, the driving force for Y 2 O 3 precipitation was large, resulting in the formation of Y 2 O 3 -precipitated powder.