Effects of Zinc and Calcium Concentration on the Microstructure and Mechanical Properties of Hot-Rolled Mg-Zn-Ca Sheets

Four kinds of Mg alloys with different Zn and Ca concentration were selected to analyze the effect of Zn and Ca concentration on the microstructure and the mechanical properties of Mg-Zn-Ca alloys. It was found that Zn and Ca concentration has a great influence on the volume fraction, the morphology and the size of second phase. The Mg-1.95Zn-0.75Ca (wt%) alloy with the highest volume fraction, continuous network and largest size of Ca2Mg6Zn3 phase showed the lowest elongation to failure of about 7%, while the Mg-0.73Zn-0.12Ca (wt%) alloy with the lowest volume fraction and smallest size of Ca2Mg6Zn3 phase showed the highest elongation to failure of about 37%. It was suggested that uniform elongations of the Mg-Zn-Ca alloys were sensitive to the volume fraction of the Ca2Mg6Zn3 phases, especially the network Ca2Mg6Zn3 phases; post-uniform elongations were dependent on the size of the Ca2Mg6Zn3 phase, especially the size of network Ca2Mg6Zn3 phase. Reduction in Zn and Ca concentration was an effective way to improve the room temperature ductility of weak textured Mg-Zn-Ca alloys.