Fabrication of full density near-nanostructured cemented carbides by combination of VC/Cr3C2 addition and consolidation by SPS and HIP technologies

The aim of present work is to study the effect of VC and/or Cr3C2 in densification, microstructural development and mechanical behavior of nanocrystalline WC-12wt.%Co powders when they are sintered by spark plasma sintering (SPS) and hot isostatic pressing (HIP). The results were compared to those corresponding to conventional sintering in vacuum. The density, microstructure, X-ray diffraction, hardness and fracture toughness of the sintered materials were evaluated. Materials prepared by SPS exhibits full densification at lower temperature (1100 °C) and a shorter stay time (5 min), allowing the grain growth control. However, the effect of the inhibitors during SPS process is considerably lower than in conventional sintering. Materials prepared by HIP at 1100 °C and 30 min present full densification and a better control of microstructure in the presence of VC. The added amount of VC allows obtaining homogeneous microstructures with an average grain size of 120 nm. The hardness and fracture toughness values obtained were about 2100 HV30 and close to 10 MPa m1/2, respectively.

Research Highlights
► WC-12Co-VC/Cr3C2 cemented carbides near fully dense were obtained by SPS and HIP at 1100 °C.
► The addition of inhibitors, especially VC, has been demonstrated to be an efficient method for controlling the grain growth in the solid state.
► The VC addition and HIP sintering allowed manufacturing near-nanostructured cemented carbides.
► Materials with hardness values about 2100 HV30 and fracture toughness values close to 10 MPam1/2 were obtained.