THE FAILURE BEHAVIOR OF EXTRUDED Mg-12Gd-3Y-0.4Zr ALLOY SUBJECTED TO IMPACT LOADING
Dynamic failure behaviors of the extruded Mg -12 Gd -3 Y -0.4 Zr alloy were investigated by means of optical microscope and scanning electron microscope (SEM). The dynamic tensile and compressive tests were carried out at 423K~798K and strain rates of 102~103s-1 using a split Hopkinson pressure bar. Additionally, in order to study the failure characteristic of this alloy at higher strain rates, such as 107s-1, a series of ballistic tests were carried out. The results indicate that the failure mechanisms of both tensile and compressive specimens exhibit an obvious dependence on the temperature. As the testing temperatures increased from 423K to 798K, the fractographs of the tensile specimens varied from quasi-cleavage fracture to intergranular rupture, and the failure modes of the compressive specimens changed from shear cracks to dynamic recrystallization zone. Adiabatic shear bands with an average width 10µm were observed in the post-test magnesium targets penetrated by steel balls.