High hardness-high toughness WC-20Co nanocomposites: Effect of VC variation and sintering temperature

WC-Co nanocomposites with variable VC content are synthesized by liquid phase sintering at two different temperatures. The as synthesized samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) and optical microscope. The mechanical properties are obtained by Vickers indentation method. The high content of VC, lead to high porosity when sintering temperature is increased from 1350 to 1400 degrees C. The relative density of all the samples is more than 95%. Microstructure reveals that agglomeration of W-Co-C and V-W-Cincreases at 1400 degrees C, which generates layered interfaces in radial direction and hence the material inhomogeneity. XRD pattern shows that the formation of eta phase increases at 1400 degrees C, which is responsible to decrease the fracture toughness of the present samples. The average particle size of 102 nm, highest hardness of 1870.6 kgf/mm(2) with fracture toughness of 14.4 MN/mm(3/2) is observed in sample having 7.5 wt VC, sintered at 1350 degrees C for one minute. This combination shows the highest hardness and reasonably high toughness as compared to conventionally sintered materials reported so far. (C) 2016 Elsevier B.V. All rights reserved.