Synthesis and characterization of a MoWC-WC-NiC nanocomposite via mechanical alloying and sintering

MoWC-NiC-WC was produced by mechanical alloying at different grinding times as follows: 0, 40, 80, 120, 160, 200 and 240h. A mixture of elemental powders of W, Mo, C and Ni was submitted to mechanical alloying in a ball mill under an argon atmosphere. The milled powders were sintered at 900°C for 1h. The phases and morphology at each stage of milling were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD indicated that by increasing the milling time from 0 to 240h, the nanostructured carbide phases were synthesized with a crystal size ranging from 125.6 to 10.1nm. The experimental results demonstrated that after sintered milled powder at 240h, particles with spherical morphology were formed. The elemental maps revealed the formation of heterogeneous spheres which are primarily MoWC. The TEM results of sintered composites that were milled for 240h showed nanoparticles ranging from 2.5 to 50nm. As the milling time increased, the microhardness increased from 70 to 248Hv using the sintered powder milled for 240h. The surface area specific properties of the milled powders ranged from 21.60 to 88.15 m²g^-1.