Study On The Microstructures And Corrosive Properties Of Mg-Zn-Y Alloys

To abroad the applications of Mg alloys, this paper study the influence of conventional solidification, rapid solidification (RS) and reciprocating extrusion (RE) to the microstructures and erosion resistance of Mg-Zn-Y alloys, as well as the corrosion mechanism of RS Mg-Zn-Y alloys in NaCl solution. The microstructures and phases of the alloys were analyzed by OM, SEM and XRD; the erosion resistance of the alloys prepared by different processing were measured under the conditions of simulated-brine and salt atmosphere, besides the various corrosive rates were calculated by the method of weight lost; the lows of corrosion were analyzed by the electrochemical polarization curve, and the corrosive current was measured through the method of Tafel linear extrapolation. The conclusions are as follows.1. Well distributed cathodal phases are very important to the corrosion resistance of Mg-Zn-Y alloys. The refinement of grains can improve the uniformity of corrosion.2. Mg-Zn-Y alloys activate on the anode, however, when the imposed voltage is from -0.7V to -1V both of Mg_90.85Zn_7.33Y_0.84Zr_0.6Ce_0.38 and Mg_91.22Zn_6.59Y_0.79Zr_0.73Ce_0.67 change from activated state to inactivated state.3. In NaCl solution the corrosion of Mg-Zn-Y alloys develop from pit corrosion to general corrosion.4. The corrosive rate of Mg-Zn-Y alloys increase with the time firstly, and then decrease gradually after it reach the peak value; as the pH of solution increase, the corrosive rate reduce obviously; as the concentration of solution increase, the corrosive rate increase gradually.