Effect of doping Al on the microstructure of Cu-Ni-NiFe2O4-NiO cermets

Abstract

Cu-Ni-NiFe2O4-NiO cermets doped with Al (0, 0.8, 2, 3.2 wt% ) were prepared by a powder metallurgy process. The effect of Al content, Al adding method and sintering temperature on the microstructure of the cermets were studied using XRD, SEM/EDS, and DSC. The results show that NiO and NiFe2O4 phase are partly reduced to Ni by adding Al at the sintering temperature. The Al element is mainly distributed in the NiFe2O4 phase, and the doping of Al is not conducive to the densification of cermet. The density of the cermet decreases with increasing Al content. The morphology of the metallic phase is related to the Al adding method. Specimens prepared by pre-alloying of Al show smaller metallic particle size than that by mixing of Al. However, the Al adding methods have little effect on the densification and the phase composition. The sintering temperature around the solid phase line of the metallic phase is beneficial to the densification.