6061 Al reinforced with silicon nitride particles processed by mechanical milling

Abstract

This study focused on the characterization of a new graphene oxide (GO) reinforced Al–10Ni/GO metal matrix composite fabricated by mechanical alloying technique. The effect of ball milling time and sintering temperature on the microstructural evolutions, wear behaviour, mechanical and thermal properties of the fabricated composites were investigated. X-ray diffractometer and scanning electron microscope analysis showed that as the ball milling time increased, the particle size decreased, the homogeneity increased, and the Al3Ni2 intermetallic phase occurred after 40 h of ball milling. The thermal properties of the prepared powder composites were investigated with a differential thermal analyzer (DTA). DTA results showed a series of reaction peaks, which were attributed to the melting of the eutectic Al phase and the crystallization of the Al3Ni2 phase, in the temperature range of 560–655 °C. Also, as the ball milling time and sintering temperature increased, it was observed that the microhardness of the pressed powder alloys increased as a result of cold-welding of the reinforcement with the matrix material, and the occurred intermetallic phases. The maximum microhardness value of Al–10Ni/1 wt%GO composite, which was ball milled for 50 h and heat-treated at 600 °C, was found to be 315 ± 10 HV1. Furthermore, the wear behaviours were investigated under loads of 5–15 N. It was observed that as the load increased, the mass loss increased, and the mass loss decreased as the sintering temperature and milling time increased. In addition, the maximum and minimum coefficients of friction were found to be 0.50 and 0.27, respectively. As a result, it is observed that increasing the amount of GO reinforcement in the matrix from 1 wt% to 2 wt% adversely affects the properties of the composite.