Microstructure and Deformation Characteristics of Directionally Solidified Mg–Zn–Y Alloys with Excellent Ductility

The Mg–Zn–Y alloy having $$\left\langle {11\bar {2}0} \right\rangle $$ oriented columnar crystals was prepared by directional solidification, and its microstructure and tensile properties were investigated. Furthermore, the relationship between twins and strain field evolution during tensile deformation was investigated by Scanning Electron Microscope-Digital Image Correlation Method (SEM-DIC). With increasing tensile strain, $$\left\{ {10\bar {1}1} \right\}$$ contraction twins and $$\left\{ {10\bar {1}1} \right\}$$ – $$\left\{ {10\bar {1}2} \right\}$$ double twins are activated. These contraction twins can transmit across grain boundaries to form adjoining twin pairs (ATPs). SEM-DIC data shows that the formation of ATPs can effectively coordinate strain on both sides of grain boundaries. Therefore, the elongation of the alloy is as high as 42% at room temperature.