Microstructural Characterization and High‐Temperature Mechanical Behavior of Cast Mg–4Zn– x Si Alloys

Effects of 1, 2, and 3 wt% Si additions on the microstructure and mechanical properties of a cast Mg–4%Zn alloy was investigated. High temperature shear punch test was used for evaluating mechanical properties of the alloys in the temperature range of 25–250 °C. The obtained results showed that addition of Si resulted in the formation of the thermally stable Mg 2 Si intermetallic particles, which significantly increased high‐temperature strength of the base alloy. The ductility, however, decreased after Si addition, mainly due to the presence of coarse Mg 2 Si particles having a Chinese script morphology. These particles can act as suitable sites for the initiation of microcracks, which leads to void formation at the interface of the Mg 2 Si intermetallic particles and the Mg matrix. To avoid ductility losses and to have strength enhancements, the Si content of the alloy should not exceed 1 wt%.