Effect of a slight change in carbon content near the upper/lower limit on the microstructure and mechanical properties of WC-10Co cemented carbides

Abstract

To scientific understanding the effect of a slight change in carbon content near the upper/lower limit on alloys, five sets of WC-10Co cemented carbides were prepared with the carbon content of 5.34 wt%, 5.36 wt%, 5.44 wt%, 5.53 wt% and 5.56 wt% respectively. The properties of the alloys are analyzed by SEM, XRD, Hardness tester, universal testing machines, HSR-2 M tribometer, and surface characterisation. The results showed that the existent of multi-steps proved that the WC coarsening process was governed by 2-D nucleation in the alloy with low carbon content. On the contrary, the low W solubility in Co and the low melting point of Co binder accelerated the dissolution-precipitation process with increasing carbon content. At this time, the morphologies of WC grains tented to be the triangular shape without multi-steps due to the continuous grain growth. Additionally, the increasing of the value of carbon content brought about the coarser WC grain size, and the particle size distribution with “double peak” was also observed in the alloy with free carbon. Further analysis of XRD, the various dissolution of W in Co binder phase brought about a minor different intensity of the basal plane (0001) peaks. Moreover, a slight change in carbon content near the upper/lower limit also significantly affected the mechanical properties of alloys. The cemented carbides with 5.44 wt% carbon content in two phase range exhibited a combination of superior mechanical properties and wear resistance.