Investigation on morphology evolution of coarse grained WC–6Co cemented carbides fabricated by ball milling route and hydrogen reduction route

• The preparation method of WC–6Co powder affects the growth mechanism of WC crystal.
• Multi-steps in ball milling route are attributed to the defect-assisted growth of WC crystal.
• Defect-assisted growth is against the formation of homogeneous plate-like WC crystal.
• WC–6Co cemented carbide from hydrogen reduction route possesses the best mechanical properties.

WC–6Co powders were fabricated via hydrogen reduction and ball milling routes. The influences of powder preparation method on the morphology evolution of WC crystals and mechanical properties of WC–6Co cemented carbide were systemically investigated. In the case of ball milling, some multifaceted WC crystals contained multiple step features and the number of these multi-steps increased with ball milling time. In the case of hydrogen reduction, no multi-steps occurred and the plate-like WC crystals formed. The differences on morphology of WC crystals might be ascribed to the shift of the growth mechanism of WC crystals from a 2D nucleation mechanism to a defect-assisted mechanism. WC–6Co cemented carbide obtained from the hydrogen reduction route showed the improved mechanical properties, a superior combination of hardness, fracture toughness and strength, compared to those obtained from the ball milling route.