Fabrication of Ni/SiC composite powder by mechanical alloying and its effects on properties of copper matrix composites

Abstract

AbstractComposite powders of Ni-30SiC (vol.%) were fabricated by mechanical alloying. Scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy were used to analyze the microstructure, morphology and composition of the composite powders. Mixed powders and Ni coating layers on the surface of SiC particles were investigated. The Ni/SiC composite powder with the optimal coating was mixed with Cu powder to manufacture Cu matrix composites by powder metallurgy, and the relative density, hardness and electrical resistivity of the composites were measured. The results show that the Ni coating becomes increasingly prominent and that the mixed powders become increasingly homogeneous as the ball-milling time increases; however, an excessively long milling time has a negative impact on the coating. The milling speed also has an important effect on the coating. Too high of a rotational speed quickens the rate of work hardening of the coating layer, which causes the coating layer to fall off. When the milling time is 20 h, the milling speed is 300 r min−1 and the ball to powder weight ratio is 10 : 1, the SiC particles are well coated by Ni and the powders are uniformly mixed. The properties of the copper matrix composite processed with the optimal milling parameters are effectively improved.