Surface Alloying Of Some Cu-based Powder Metallurgy Materials By High Current Pulsed Electron Beam

Copper alloys have been widely used in the industry because they not only preserve the conductivity of copper but also own the properties of alloy elements.Surface treatment technology is able to improve the surface properties of copper alloy,and thus,extend the service life of copper alloy,which plays a vital role in the development of the whole industry.In this paper,the High Current Pulsed Electron Beam(HCPEB)is used to treat the surface alloying of the Cu-20 Cr and Cu-20 Fe alloys that were prepared by powder metallurgy.Then we analyze the surface composition modifications with and without irradiation by the X-ray diffractometer(XRD).Next,the surface morphology and microstructure of the original and irradiated samples were obtained by scanning electron microscope(SEM),three-dimensional laser scanning microscope(LSM)and transmission electron microscope(TEM).Further,the surface microhardness of original samples and the surface alloying powder metallurgy samples were measured and analyzed by microhardness meter.Finally,friction and the wear tests were carried out on the original samples and the surface alloying samples by using a friction and wear tester,next to it,the morphology of the worn powder metallurgy samples were observed by using SEM and LSM.We analyze the changes of surface morphology,microstructure and surface hardness of Cu-20 Cr and Cu-20 Fe powder metallurgy samples under different irradiation pulses,and establish the influence mechanism of pulse numbers on the surface alloying of copper powder metallurgy.The results showed that the existence of pits was obvious observed on the surface of Cu-20 Cr and Cu-20 Fe powder metallurgy samples after low irradiation pulses.These pits are removed with the increasing pulses of irradiation increases.The added alloying element particles significantly refined and dispersed in the Cu matrix after HCPEB surface treatment.In addition,HCPEB induces type-rich,high-density crystal defect structures in the Cu matrix,and refines the Cu grains,which dramatically increases the grain boundary volume fraction.The formation of grain boundaries and structural defects strongly promote the diffusion of elements between Cu-Cr and Cu-Fe insoluble systems,which in turn forms supersaturated solid solutions in the irradiated surface.Microhardness results show that HCPEB surface treatment obviously improved the surface microhardness of the two powder metallurgy samples.Moreover,with the increase of irradiation pulses,the surface microhardness show an increasing trend.The friction and wear test results show that the friction coefficient and wear rate of the two samples were decreased after surface treatment;and the friction coefficient and wear rate were obviously decreased with the increase of irradiation pulses.In addition,the wear surface also becomes more and more flat with it.