Microstructures and Formability of the As-Rolled Mg-xZn-0.5Er Alloy Sheets at Room Temperature

As lightweight requirements rise in transportation, aerospace, and other industries, magnesium alloys have a great application prospect. However, the low formability capabilities of magnesium alloys lead to a severe limit in applications. At present, there are many reports on the influences of texture and second phases on the formability of magnesium alloys at room temperature. Nevertheless, the dominant factors affecting the formability performance of magnesium alloys at room temperature are not clear. In this study, the development of the microstructures and texture of Mg-xZn-0.5Er (x = 0.5, 2.0, 3.0, 4.0, mass fraction, %) alloy sheets were studied, and the impact of the texture and second phases on the formability of these sheets were also investigated. The findings showed that the increase in Zn addition led to an early and complete dynamic recrystallization (DRX) in Mg-Zn-Er alloys sheets, and these recrystallized grains would expand significantly during subsequent hot rolling processes. These recrystallized grains with a large size were typically elongated and then helped to create a strong basal texture. Thus, it was discovered that the microstructures of these sheets were typically made up of equiaxed and elongated grains. The formability performance of these sheets was strongly related to the size of the second phases and the texture. The formability of the sheets containing microscopic second phases mainly depended on the basal texture, while the formability of the sheets which contained coarse second phases was mostly influenced by the second phases and basal texture. Particularly, when the component of the coarse second was larger, the formability would get more inferior due to the predominant role of the second phase at room temperature.