Improvement of wetability, sinterability, mechanical and electrical properties of Al2O3-Ni nanocomposites prepared by mechanical alloying

Abstract

The wetability improvement and particle size reduction of alumina/Ni composites through mechanical alloying were addressed. Their effect on the sinterability (at high temperature), mechanical and electrical properties were studied. Al2O3 matrix nanocomposites reinforced with different volume fractions of Ni up to 10vol% were prepared by mechanical alloying. The milled powders were cold pressed and sintered at different firing temperatures up to 1600°C. The morphology of powders and the microstructure of sintered bodies were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), respectively. Furthermore, relative density, apparent porosity, mechanical properties and electrical resistivity of the sintered composites were investigated. The results revealed that Al2O3 matrix was successfully coated with Ni thin film through mechanical alloying; the thickness of coat was increased with increasing the Ni content. Moreover, the increasing of both Ni content and sintering temperature up 1600°C, led to a remarkable increase in the relative density and facture toughness of the sintered specimen. On the other hand, microhardness and elastic modulus were decreased with increasing of Ni content, while they increased significantly with the increase of sintering temperature. The electrical resistivity was decreased with increasing Ni content and sintering temperature.