Effects of Cr3C2 additions on the densification, grain growth and properties of ultrafine WC-11Co composites by spark plasma sintering

Cemented carbide powders based on WC-11Co with a grain size of about 250 nm added various extents of Cr3C2 were consolidated to full density by spark plasma sintering (SPS). The density, hardness and fracture toughness of the SPS consolidated samples were measured and the microstructure, fracture surfaces and grain size were observed by SEM. XRD investigation of the spark plasma sintered WC-Co samples revealed that no new phase formed. The WC-11Co composite powder were fully densified within 5 min by SPS at the temperature of 1200 degrees C, which is much lower temperature than that of conventional liquid phase sintering, under a pressure of 40 MPa. Addition of grain growth inhibitors Cr3C2 reduced the grain size to 435 nm, but led to the lower density. The adding amount of Cr3C2 should be controlled within a certain range, and the samples adding the appropriate proportion of Cr3C2 can obtain higher hardness and toughness. (C) 2007 Elsevier Ltd. All rights reserved.