Fracture analysis of cobalt-bonded tungsten carbide composites

Specimens of WC-Co were indented to measure the resulting crack size and unindented samples were fractured in three-point flexure to obtain strength and to measure characteristic features on the fracture surface. Fracture toughness was determined using indentation techniques and compared to those determined using fractography. We show that principles of fracture mechanics can be applied to WC-Co composites and can be used to analyse the fracture process.The fracture surfaces were examined by scanning electron microscopy and optical microscopy. Characteristic features observed in glasses, single crystals and polycrystalline materials known as mirror, mist, hackle and crack branching were identified for these composites. We discuss the importance of fracture surface analysis in determining the fracture origins and in the failure analysis of WC-Co composites.