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∥〈c〉 and ID⊥〈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 {101̄2} extension twins are activated and the strain hardening rate exhibits a sharp increase and then decrease for the ID⊥〈c〉 specimen, while a small number of twins are observed and the hardening rate decreases monotonically for the ID∥〈c〉 specimen. As a result of the anisotropic distribution of the β-Mg17Al12 phase, cracks are generally distributed in the mid-part and connected together for the ID⊥〈c〉 case, while the distribution of cracks in the ID∥〈c〉 specimen is relatively discrete along the ID and parallel to the rolling plane.