Effect of Extrusion Process on Microstructure, Corrosion Properties, and Mechanical Properties of Micro-Alloyed Mg-Zn-Ca-Zr Alloy

The effect of the extrusion process on the microstructure, corrosion, and mechanical properties of Mg-Zn-Ca-Zr alloy has been investigated. Zn and Ca were both in a solid solution and only the Zr-rich phase was observed in the homogenized and extruded alloys. The Zr-rich phase was obviously refined after extrusion. The corrosion rate of the homogenized alloy decreased by about 25% after extrusion. This is because the refined Zr-rich phase was easier to cover with the deposited corrosion products, which reduced the cathodic reaction activity of the Zr-rich phase. The corrosion rate is similar for the alloys extruded at 320 degrees C and 350 degrees C since the size and distribution of the Zr-rich phase were not different in the two conditions. The alloy extruded at 320 degrees C has a smaller grain size and better comprehensive mechanical properties.