Characterization of Ball Milled Ni–Al2O3 Nanocomposite Powders

Abstract

Homogenous Ni–Al2O3 nanocomposite powders with uniform distribution of Al2O3 nanoparticles were obtained through ball milling of Ni and Al2O3 powders for 9 hours. Field emission scanning electron microscopy and X-ray mapping were used to characterize the ball milled powders and Al2O3 nanoparticles’ dispersion, respectively. The evolution of crystallite size and lattice strain in the nanostructured Ni powder was followed through X-ray diffraction. It was found that ball milling led not only to the uniform dispersion of the Al2O3 nanoparticles, but also to the reduction in crystallite size and increase in the lattice strain of the Ni phase. For the composite containing 5 wt.% Al2O3, the increase of milling time from 0 to 9 hours led to a continuous decrease of the crystallite size of the Ni phase from 1120 to 36 nm. For the composite containing 10 wt.% Al2O3, the increase of milling time from 0 to 2 hours augmented the lattice strain of the Ni phase and a further increase of milling time to 9 hours led to its decrease.