On plastic deformation mechanisms of WC–15 wt% Co alloys at 1000 °C

WC–15 wt% Co samples with and without VC doping have been tested in three-point bending at 1000 °C. The strain at fracture was found to be as high as 4.7%. Fractographic as well as macrostructural and microstructural investigations have been carried out on the tested samples to identify the mechanisms leading to the high strain. Up to 10% of the strain has been found to be due to cracks which initiated at or near the tensile face of the samples. Majority of the strain was found to be due to the drifting of the binder phase, which at 1000 °C appears to acquire a viscous consistency. No evidence of grain boundary sliding was found, but is expected to occur, on the basis of previous work. In the case of VC-doped samples a large number of WC/Co interfaces exhibiting steps were observed on the fracture surfaces which are possible preferred sites for fracture propagation.