Influence of Milling Time on the Homogeneity of the Al<sub>2</sub>O<sub>3</sub>/Ni Composite Powders Obtained by Mechanical Milling

Abstract

Al2O3/Ni nanocomposite powder was obtained by high-energy mechanical milling starting from a mixture of Al2O3 and Ni commercially powders. The Al2O3+15%vol. Ni mixture was homogenized for 15 minutes in the Turbula-type blender and then was milled in a planetary ball mill (Fritsch, Pulverisette 4) under argon atmosphere up to 120 min. Several milling times were used: 10, 30, 60, 90 and 120 minutes respectively. The evolution of the powders during milling and the stability of the composite phases were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). The SEM and OM images show a high level of homogenization of the Ni and Al2O3 phases for milling times larger than 90 minutes. The X-ray studies indicate no mixing between the two phases. The crystallite grain size is decreasing with the milling time.