Mechanical properties and fracture behavior of Mg-3Al-1Zn alloy under high strain rate loading

Gas-gun experiments are carried out to study the mechanical properties and fracture behavior of a textured Mg-3Al-1Zn alloy under high strain rate. The impact direction (ID) is either perpendicular or parallel to crystallographic {0001} planes, referred to as ID parallel to < c > and ID perpendicular to < c >, respectively. Shock compression and spallation are achieved with different specimen-to-flyer plate thickness ratios. The Hugoniot elastic limits and spall strengths are estimated as 0.32-0.35 GPa and 0.9-0.92 GPa, respectively, showing weak anisotropy. The deformed specimens are characterized with scanning electron microscope and X-ray computed tomography. Abundant {10 (1) over bar2} extension twins are activated and the strain hardening rate exhibits a sharp increase and then decrease for the ID perpendicular to < c > specimen, while a small number of twins are observed and the hardening rate decreases monotonically for the ID parallel to < c > specimen. As a result of the anisotropic distribution of the beta-Mg17Al12 phase, cracks are generally distributed in the mid-part and connected together for the ID perpendicular to < c > case, while the distribution of cracks in the ID parallel to < c > specimen is relatively discrete along the ID and parallel to the rolling plane.