Effects of WC size and amount on the thermal residual stress in WC-Ni composites

Effects of WC particle size and volume fraction on the magnitude and distribution of thermal residual stresses (TRS) in WC-Ni cemented carbide composites were studied by neutron powder diffraction. Samples of high (0.3) and low (0.1) Ni volume fraction and coarse (1.7 μm) and fine (0.5 μm) WC particle size were employed. Thermal residual strain and stress values were obtained at temperatures between 100 and 900 K. The magnitude of the mean (compressive) WC stress increased as WC fraction decreased, while the mean (tensile) Ni stress did the opposite. For both phases, stresses were highest for fine WC particles, reaching over 3 GPa in Ni. Elastic strain distributions, due to the sharp edges and corners of WC particles, were characterized by analyzing diffraction peak widths. The range of stress increased with the magnitude of the TRS. Even though the mean TRS is compressive in WC, regions of tension exist, and, for Ni, regions of compression are present.