In this study, compounded surface modification technology- high current pulsedelectron beam (HCPEB) + micro-plasma oxidation (MPO) was applied to treat ZK60 Mg alloys.The characteristics of the microstructure of ZK60 Mg alloy after single MPO and HCPEB+MPOcompounded treatment were investigated by SEM. The results showed that the density of theceramic layer of HCPEB+MPO-treated ZK60 Mg alloy was improved and defects were reducedcompared to that under MPO treatment alone. Surface modified layer of ZK60 Mg alloys treatedby HCPEB+MPO was divided into three zones, namely the top loose ceramic zone, middle compactzone and inside HCPEB-induced melted zone. Corrosion resistance of ZK60 Mg alloy beforeand after the compounded surface modification was measured in a solution of 3.5% NaCl by potentiodynamicpolarization curves. It was found that the corrosion current density of ZK60 Mgalloys could be reduced by about three orders of magnitude, from 311 μA/cm^2 of the originalsample to 0.2 μA/cm^2 of the HCPEB+MPO-treated sample. This indicates the great applicationpotential of the HCPEB+MPO compounded surface modification technology in improving thecorrosion resistance of ZK60 Mg alloys in the future.
The mechanical properties of hypereutectic Al-Si alloys are mainly determined by size and morphology of the primary silicon phase.So,optical microscopy(OM) and X-ray diffraction(XRD) were adopted to study affection of Nd on primary silicon of hypereutectic Al-15%Si alloy in this paper.The results of OM showed that pure Nd could effectively refine primary silicon of hypereutectic Al-15%Si alloy.When Nd addition was 0.3%,the average size of primary silicon reduced from 20-40 μm of initial sample to 10-20 μm of modified sample.XRD pattern showed that no new phase was formed after Nd modification.The results of mechanical properties test showed that whole properties of modified samples were significantly improved.Tensile strength increased about 32.6% from 147 MPa to 195 MPa.Elongation was increased about 160% from 1.0% to 2.6%.The improvement of mechanical properties should attribute to primary silicon refinement after modification.
