Surface microstructure modifications and in-vitro corrosion resistance improvement of a WE43 Mg alloy treated by pulsed electron beams

Abstract

In the present study, the surface microstructures and in-vitro corrosion resistance of an as-cast WE43 Mg alloy after high current pulsed electron beam (HCPEB) treatments are investigated. It is shown that the surface presents craters and wavy morphology after HCPEB treatments, which are the typical characteristics of the morphology after rapid melting and cooling. The initially existed Mg14Nd2(Y,Gd) particles are dissolved, and the fine β՛ (c-bco, a = 0.64 nm, b = 2.223 nm and c = 0.521 nm) precipitates are formed and homogeneously dispersed in the treated layer. The electrochemical measurements in the simulated body fluid (SBF) show that the corrosion current density (Icorr) of the 15 pulsed sample (2.66 × 10−5 A cm−2) is reduced by an order of magnitude compared to that of the untreated sample (1.91 × 10−4 A cm−2), and the polarization resistance (Rp) is increased by 176.9%. The disappearance of second phase, the formation of homogeneous dispersed β՛ nano-precipitates and the chemically homogenized melted layer account for the improved corrosion resistance of the 15 pulsed WE43 sample in SBF.