Microstructure evolution and constitutive relation establishment of extruded Mg-1Al-6Y alloy under high speed impact

The dynamic mechanical behaviors of the as-extruded Mg-1Al-6Y alloy was investigated by using split Hopkinson pressure bar (SHPB) at strain rates of 587 s−1- 1986 s−1 and temperatures of 293–623 K. The results revealed that the microstructures and deformation mechanisms of the extruded alloy are sensitive to the strain rates and temperatures. The yield strength and compressive strength of the alloy are obviously improved with the increases of strain rate and weakened with increases of temperature. The experimental results demonstrated that the extension twinning and dislocation slips are the dominant deformation structures during the high strain rates impact. Temperatures have great influences on the dynamic mechanical behaviors of Mg-1Al-6Y. It is easy to form basal textures during the high-speed impact process of the alloy. A new constitutive model based on the Johnson-Cook model has been constructed to study the dynamic mechanical behaviors of the alloy. It is found that the new equation could accurately predict the flow stresses and deformation behaviors of the alloy under the slip-dominated condition.