Dynamic compressive behavior and damage mechanism of cast magnesium alloy AZ91

The mechanical behavior of cast AZ91 under a wide range of strain rates (10^-3-10⁴ s^-1) was described by using INSTRON testing system and Split Hopkinson Pressure Bar. The dynamic behavior (strain rate 6 × 10²-1 × 10⁴ s^-1) of AZ91 was studied. The fracture surface of samples at different strain rates was examined by scanning electron microscope (SEM). The results show that the cast AZ91 has obvious strain hardening character at room temperature. The mechanical behavior of cast AZ91 declines as the strain rate increases under a low strain rate range (10^-3-10^-1 s^-1). When the strain rate exceeds 7 × 10³ s^-1, the cast AZ91 shows strong strain rate sensitivity. And the microstructure of the sample's fracture surface exits great difference under different strain rates.