Surface composite microstructure and improved mechanical property of YG10X cemented carbide induced by high current pulsed electron beam irradiation

The surface microstructure evolution and its effect on mechanical property was systematically investigated for YG10X cemented carbide irradiated by high current pulsed electron beam (HCPEB) with a steady energy density of 6 J/cm(2) and different pulse numbers. The surface morphology was characterized by optical microscopy (OM), three-dimensional laser scanning microscopy (LSM) and scanning electron microscopy (SEM); and energy dispersive spectrometry (EDS) and X-ray diffractometry (XRD) was carried out to reveal the elemental profile and phase transformation under HCPEB irradiation. During the HCPEB-induced rapid re-melting and re-solidification process, the redistribution of chemical elements, grain refinement and phase transformation WC(hex) -> graphite + beta-WC1-x(fcc) occurred. Moreover, the preferential precipitation of nano-grained graphite in the Co-rich region of melt pool was discovered. The drastic structural change led to a maximum similar to 34% increment of the initial state in microhardness and about a two third reduction in friction coefficient.