Mechanical Characterization of Bimodal Grain Size Aluminum 5083 Under Various Test Conditions

A 5083 aluminum alloy with a bimodal grain size distribution consisting of a nanocrystalline grain matrix, created by cryomilling, and coarse grains has been produced. This material has been shown to exhibit greatly improved properties when compared to conventional Al-5083 and nanocrystalline aluminum. This work investigates how the test conditions affect the mechanical behavior of this material. A full factorial experiment is designed to investigate effects of strain rate, size, material orientation, and coarse grain volume ratios through uniaxial tensile tests. The results are found to conform well to Joshi’s model for plasticity. Strength and ductility is found to decrease with increasing strain rate and specimen thickness is found to affect the stiffness of the material. Increasing coarse grain ratio is found to increase ductility, though it appears that the effect may become saturated at some point. Furthermore, significant anisotropy effects are observed.