Developing a High Ductility Mg Alloy Via Non-basal Slips and Intergranular Coordination Induced by Li and Er Addition

The poor ductility of magnesium (Mg) alloys at room temperature restricts its large-scale usage in industry. In this work, we design low-alloying Mg-3Li-xEr(x = 0.2, 0.8 wt%) alloys with high ductility. Quasi-in-situ electron back-scatter diffraction observation, combined with slip trace analysis and in-grain misorientation axes analysis, was carried out to systematically characterize the microstructural evolution and slip deformation mode during the tensile deformation of the Mg-3Li-xEr alloys. The results showed that the synergy effect of solute Li and Er dramatically reduces the critical resolved shear stress ratios between non-basal and basal slip, thus contributing to the activation of considerable non-basal dislocations. Additionally, Er microalloying increases the frequency of grain boundaries with misorientation angles (theta(s)) being in the range of 75 < theta s < 90 degrees, enhancing intergranular coordination ability by activating more basal-slip-induced prismatic < a > slips.