Magnesium alloys are an attractive material system for protection applications owing to
their high specific strength and stiffness, but have low failure strains relative to similar strength lightweight metals in this application (e.g. Aluminum). The plastic anisotropy from the low-symmetry HCP crystal structure and defects in the microstructure, such as voids and second
phase particles, may all play roles in spall, or dynamic tensile failure at rates greater than
10^5 per second. We present a large number of spall experiments on Mg-9Al (wt. %) thin film specimens
performed with a laser-driven micro-flyer apparatus. The Mg-9Al alloy is warm-rolled and processed in two conditions: (a) fully solutionized at 450oC for 24 hours
with no second phase particles and (b) peak aged to generate high aspect-ratio lath precipitates (Mg17Al12) with thicknesses on the order of nanometers and lengths on the order of microns on the basal plane. The loading direction is varied between the normal-to and transverse-to rolling directions of the specimen to interrogate the effects of plastic anisotropy of the matrix
material and geometric anisotropy of the precipitates on the spall strength. We compare the experiments to numerical simulations that use crystal plasticity and realistic precipitate habit planes, geometries, and spacings from transmission microscopy observations.