Deformed Microstructure of AZ91 Magnesium Alloy Impacted by Projectiles with Velocities of 2-3 km/s

Abstract

AZ91 magnesium alloy in different heat treatment conditions was impacted by GCr15 steel projectile (2 km/s, power gun) and 2017 Al alloy projectile (3 km/s, two-stage light gas gun). Deformed bands, plastic flow and a wealth of cracks were observed near the crater in as-cast magnesium alloy impacted by GCr15 steel projectile, while for the solution treated alloy, both deformed and transformed bands were observed accompanied by fewer cracks near the crater. Upon higher velocity impact using two-stage light gas gun, many cracks and severe deformed areas containing a number of elongated grains were observed near the crater for both hot-forged and solution-treated targets, while fewer adiabatic shear bands could be found. Most of these shear bands were located at the end of cracks. The strain hardening at different zones under the crater was also investigated.