Characterizing microscale deformation mechanisms and macroscopic tensile properties of a high strength magnesium rare-earth alloy: A combined experimental and crystal plasticity approach

Abstract

The effect of aging on the accumulation of microscale plasticity, and the resulting macroscopic mechanical behavior, were examined in the magnesium alloy WE43 under uniaxial tension. Full-field strains on the length scale of the microstructure, and their relation to the underlying crystallography, were captured using a combination of electron backscatter diffraction, custom nanoparticle patterning processes for corrosion-susceptible alloys, scanning electron microscopy (SEM), in-SEM uniaxial tensile and compressive loading, and distortion-corrected digital image correlation. The as-received material exhibited an average grain size of 12 µm. The strain incurred on individual slip traces in magnesium was resolved for the first time. Insights into slip activation across the microstructure revealed that using Schmid's Law with the nominal Schmid Factor appeared to be predictive for basal and non-basal slip. The DIC results were compared with simulation using an advanced open-source crystal plasticity finite element (CPFE) code, PRISMS-Plasticity. The PRISMS-Plasticity model is a more precise determination of the local Schmid Factor and was used to simulate variations in slip and twin activity within each grain. Such simulations provide an avenue for physically interpreting the various slip traces observed in the dense DIC data and an improved understanding of the critical resolved shear stress of the various slip systems.