A study of nanocrystalline nickel powders developed via high-energy ball milling

Nanocrystalline nickel powder from pure nickel with an initial particle size of 4–7 μm was fabricated using high-energy ball mill technique at different milling parameters. The resulting milled slurries were dried and characterized with the aid X-ray diffraction and scanning electron microscopy. The X-ray diffraction (XRD) results show that nanocrystalline size of 7.867 nm and 8.866 nm were attained after 10 h milling at constant ball-to-powder weight ratio (BPR), and 20:1 BPR at constant milling time respectively. Nanocrystalline size of the nickel powder was observed to reduce as the milling time increases under constant BPR. However, drastic reduction to nanosize was obtained within short duration when the BPR increases. The microstructural orientation with respect to BPR and milling time variations were exhaustively discussed which was characterized by cold welding and fracturing of the powders.