Synthesis and characterisation of Si 3 N 4p /Cu nanocomposite powders by high energy ball milling

The present work reported the preparation of Cu–25 wt-%Si₃N₄ nanocomposite powders via high energy ball milling (HEBM). The phases and morphologies of as-milled powders with various milling times were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The experimental results showed that with increasing the milling time, the irregularly shaped Cu powder became flattened, and, subsequently, refined and near spherical. After 12 h milling, the particle size of Cu–Si₃N₄ composite powders was in the range of 200–300 nm, while the grain size of Si₃N₄ particulates, 10–25 nm, was well within a nanometre scale. A uniform distribution of the nanosized Si₃N₄ reinforcing phase throughout the Cu matrix was successfully obtained. A reasonable mechanism for the formation of Cu–Si₃N₄ nanocomposite powders during HEBM was also proposed.