Phase response of WC-Ni to cyclic compressive loading and its relation to toughness

The interaction of uniaxial compressive load and thermal residual stress was measured in a WC-10 wt.% (16 vol.%) Ni cemented carbide composite using neutron diffraction. Loading was from 0 to −2500 MPa in increments of 250 MPa, and measurements were made in situ during load-unload cycles 1, 2, 3, 10, 25, 50 and 100. Plasticity is observed in the Ni from the lowest levels of applied load, leading to continuous curvature of the WC-Ni stress-strain curves, and is believed to be a significant contribution to the composite's toughness. It is due to interaction between local extremes of the thermal residual microstress with the applied macrostress and leads to anisotropic relaxation of the thermal residual stress. Strain distribution and plasticity were observed through peak breadths. Although the initially strong hysteresis is reduced as the cycles increase, there are still changes taking place after 100 cycles.