Simultaneous achievement of high strength and large elongation in extruded Mg/LPSO alloys via the anisotropic mechanical properties-induced ductilization (AMID) mechanism

We discovered two distinctive features in the mechanical properties of extruded Mg alloys containing a long-period stacking ordered (LPSO) phase, which are highly desirable for a new class of high-strength, lightweight materials. First, the Mg/LPSO-extruded alloy shows greater elongation compared to other Mg solid-solution-extruded alloys when a certain high strength is required. Second, the simultaneous achievement of high strength and large elongation in the Mg/LPSO-extruded alloy enhances with a reduction in extrusion speed. We clarified that the LPSO phase contributes not only to increased strength but also to enhanced elongation through an increase in the work-hardening rate, by a mechanism we termed “anisotropic mechanical properties-induced ductilization” (AMID). Based on our results, we propose an novel approach to improve the ductility of Mg alloys: increasing the elongation by locally enhancing their “anisotropic mechanical properties” through the AMID mechanism. Computational analysis further suggests that reducing the grain size of Mg-worked grains should effectively improving elongation in Mg/LPSO alloys with a high volume fraction of Mg-worked grains.