Microstructure and mechanical properties of WC–10Co cemented carbide containing VC or (Ta, Nb)C and fracture toughness evaluation using different models

This article describes a study on WC–10Co cemented carbides with different percent of grain growth inhibitors. Samples were prepared by the conventional powder metallurgy method, using WC and Co powder and different concentrations of VC and (Ta, Nb)C powder. All samples were processed using a hot isostatic press (HIP) and the effect of grain growth inhibitors on the microstructure and mechanical properties were investigated. Additionally, microstructure and powder particle morphology were examined using scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). The specimen's microstructure proved that the addition of VC is more effective at suppressing grain growth than (Ta, Nb)C. Besides the microstructure observations, hardness, transverse rupture strength (TRS) and indentation fracture toughness (IFT) were evaluated. Due to the brittleness of the cemented carbides, fracture toughness was evaluated using different IFT models. The IFT values were determined by measuring the lengths of the cracks generated at the corners of a Vicker's indentation.

► We study the effect of grain growth inhibitors in cemented carbides. ► A suitable percent of VC produces very fine grained cemented carbide. ► Indentation fracture toughness is used to get transverse rupture strengths values. ► Different theoretical models are compared and best theoretical model is introduced. ► Indentation fracture toughness values are independent to applied loads for WC–10Co and WC–VC–10Co.