The study of ternary carbides formation during SPS consolidation process in the WC-Co-steel system

Tungsten carbide has a wide range of applications, mainly cemented carbides made of WC and Co, as wear resistant materials. However, the high cost of WC-Co powders encourages the use of a substrate to manufacture a functionally graded material (FGM) tool made of WC-Co and a tool steel. These materials join the high wear resistance of the cemented carbide and the toughness of the steel. This work deals with the study interaction of the WC-Co and H13 steel to design a functionally graded material by means of spark plasma sintering (SPS). The SPS, a novel sintering technique reaching the consolidation of the powders at relatively low temperatures and short dwell times, is a promising technique in processing materials. In this study, WC, H13 steel, WC-Co, WC-H13 steel and WC-Co-H13 steel bulk samples were investigated using scanning electron microscopy and X-ray diffraction techniques to evaluate the phase transformations involved during SPS consolidation process. The W2C and W3Fe3C precipitation were identified after the SPS consolidation of the WC and WC-H13 steel samples, respectively. The precipitation of W4Co2C was also identified in the WC-Co and WC-Co-H13 steel samples. The WC-H13 steel and WC-Co-H13 steel were also evaluated after heat treatments at 1100 °C for 9 h, which enhanced the chemical interaction and the precipitation of W3Fe3C and W4Co2C, respectively.