Investigation On Surface Microstructure And Wear Resistance Of YG10 Hard Alloy After High Current Pulsed Electron Beam Irradiation

WC-Co hard alloy has been widely used in manufacturing high-quality knife mold because of its excellent combination of properties.It is of great engineering significance and practical value to improve the mechanical properties and wear resistance of WC-Co hard alloy by surface modification method for satisfying the high speed,high efficiency and longer service life of modern production.In recent years,high current pulsed electron beam(HCPEB)has developed rapidly.Because the energy density is controllable,the processing material is wide,and the modification effect is remarkable.The material surface(~ a few ?m)is rapidly heated and melted after high current pulsed electron beam irradiation along with a rapid cooling process,so that nonequilibrium phase transition of the modified surface occurs,thereby improving the wear resistance of the material surface.In this paper,High current pulsed electron beam irradiation was conducted on YG10 hard alloys.The acceleration voltage is 27 kV and the pulses' numbers are 1,3,6,10,20 and 35.The modified surface microstructure,morphology,elemental distribution and phase structure were investigated by using optical microscopy,scanning electron microscopy,EDS energy spectrometer and X-ray diffraction methods.The change of the diffraction peak of graphite(002)near 2? ~26? is mainly studied.The microhardness and wear resistance of the modified layer were measured.The modified surface microstructure and properties were investigated,in order to study the characteristics of high temperature non-equilibrium phase transition of WC and find the effective method to improve material surface performance of WC-Co hard alloys.It is found that the fast melting and solidification processes occurred in the surface layer of YG10 sample under HCPEB irradiation,where the original WC grains of size about several micrometers were refined greatly into nano scale,the Cobalt bonding phase disappeared and the net-like microcracks was observed on the modified surface.With the increasing number of HCPEB pulses,the WC phase in surface modified layer of depth ~ 1.5 ?m was replaced gradually by the new phase of WC1-x,and also the formation and redistribution of nano carbon particles and W2 C phase.The surface microhardness increased linearly with the more HCPEB pulses applied,from the initial 1735.8Hv to 3128.5Hv after 35 pulses.The best wear resistance was obtained on the sample treated by 6 pulses,where the wear rate decreased to 40% of the original sample.That was mainly attributed to the effects of surface nano refinement and diffused precipitation of carbon particles.