Effect of carbon content on the properties of inhomogeneous cemented carbides with fine-grained structures produced via one-step transformation

Abstract

Inhomogeneous cemented carbides with fine-grained structure produced via one-step transformation were prepared using coarse WC, WO3, C and Co as raw materials. The effect of carbon content on the properties of inhomogeneous cemented carbides was studied. The results indicated that the peak intensity of Co (1 1 1) had a positive relationship with carbon content. The coarse WC grains were irregularly-shaped with some growth steps and the fine grains were near-spherical shape in the alloy with low carbon content. Upon increasing the carbon content, the coarse WC grains tended to be planar and the number of growth steps decreased gradually. The number of fine WC grains increased at higher carbon contents in the WC-Co3W3C-Co alloys, resulting in a decrease in the average WC grain size. Then, the number of fine WC grains decreased and the coarse WC grains grew upon increasing the carbon content in the alloys without the Co3W3C phase, which increased the average WC grain size. The mechanical property variation of the alloys was derived from the phase composition, morphologies and the size of WC grains. Thus, the alloy with 7.24 wt% carbon displayed the maximum hardness and transverse rupture strength due to its high number of prismatic WC grains and lack of free carbon.