Mechanical Behavior and Deformation Mechanisms of Mg-based Alloys in Shear Using In-Situ Synchrotron Radiation X-Ray Diffraction

A fundamental understanding of magnesium-based alloys during high rate, large deformation processes that occur during impact and penetration are not well-known. This metal possesses a limited number of deformation mechanisms, each with their own disparate strengths, strain hardening rates, and strain rate sensitivities. Consequently, these alloys exhibit severe tension-compression asymmetry and anisotropy dictated by their processing history and the applied deformation. Thus, an understanding of material behavior undergoing large shears at dynamic rates is required. Experiments have been performed on a specimen geometry that induces shear localization in “pure” simple shear, called the compact forced simple shear (CFSS) specimen. The deformation occurs on a 2D plane in the specimen, which is oriented with respect to directional aspects of the material’s microstructure and deformation modes. Experiments at dynamic strain rates have been performed to determine how the mechanical behavior in shear evolves and correlates to the microstructural deformation mechanisms. The experiments were performed at the Dynamic Compression Sector of the Advanced Photon Source at Argonne National Laboratories using in-situ synchrotron x-ray diffraction aimed to probe the microstructural evolution during shear-induced localization. By correlating the propensity for shear localization to occur with the mechanical response of various orientations, we have built a data set to compare existing models to identify key deformation mechanisms responsible for localization.