Microstructure and corrosion properties of Mg–0.5Zn–0.2Ca–0.2Ce alloy with different processing conditions

Abstract

The microstructure and corrosion resistance of Mg–0.5Zn–0.2Ca–0.2Ce alloy with different processing conditions were investigated. The composition was detected by X-ray fluorescence (XRF), and the microstructure was analyzed by optical microscopy (OM) and scanning electron microscope (SEM) equipped with energy-dispersive spectroscopy (EDS). The corrosion behavior was investigated by hydrogen evolution tests, weight loss tests and electrochemical measurements. The Mg–0.5Zn–0.2Ca–0.2Ce alloy has much better corrosion resistance compared with the commercial AZ31 sheet, which can be attributed to its dispersive second phases and protective corrosion products film on the alloy surface. Moreover, the as-rolled Mg–0.5Zn–0.2Ca–0.2Ce alloy shows much better corrosion resistance compared with the as-extruded Mg–0.5Zn–0.2Ca–0.2Ce alloy. This can be due to three aspects: The as-rolled alloy has smaller grain size; the as-rolled alloy has lower (10 $${\bar{1}}$$ 0)/(11 $${\bar{2}}$$ 0) texture intensity; the residual stress of the as-rolled alloy is eliminated during the annealing process, but large residual stress exists in the as-extruded alloy produced by the extrusion process.