Synthesis and characterizations of nanocrystalline WC-Co composite powders by a unique ball milling process

In order to explore the high efficiency of fabricating nanocrystalline WC-Co composite powders, this paper presented a unique high energy ball milling process with variable rotation rate and repeated circulation, by which nanocrystalline WC-10Co-0.8VC-0.2Cr₃C₂ (wt pct) composite powders with the mean grain size of 25 nm were prepared in 32 min, and the quantity of the powders for a batch was as much as 800 grams. The as-prepared powders were analyzed and characterized by chemical analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential thermal analysis (DTA). The results show that the high energy ball milling with variable rotation rate and repeated circulation could be used to produce nanocrystalline WC-Co powder composites with high efficiency. The compositions of the powders meet the specifications with low impurity content. The mean grain size decreases, and the lattice distortion and the system energy increase with the increase of the milling time. The morphology of nanocrystalline WC-Co particles displays dominantly sphere shape and their particle sizes are all lower than 80 nm. The eutectic temperature of the nanocrystalline WC-10Co-0.8VC-0.2 Cr₃C₂ composites is about 1280°C.