The impact of twin boundary migration on mechanical performance of magnesium

Conference Dates

September 29-October 4, 2019


While there have been many numerical and experimental studies of various aspects of mechanical twinning in polycrystalline magnesium, little has been done to understand twin boundary migration and its influence on concurrent dislocation plasticity. Here, we investigate the migration of a single twin boundary in pure Mg and in Mg-4wt%Gd, a solution strengthened Mg alloy known to display interesting twinning behavior (Fig. 1). By utilizing a micromechanical approach along with EBSD and TEM characterization, we are able to isolate a single twin boundary of chosen orientation and analyze the structural changes and stress-strain response resultant from uniaxial loading. Microcompression experiments were carried out on microcolumns fabricated with a single twin boundary, as well as single crystals of the parent orientation as a reference. Interestingly, compression-induced detwinning was found to lead to hardening. Results will be discussed in terms of twinning and detwinning mechanisms, the influence of such mechanisms on the strength and hardening response, and the impact of Gd solutes on the twinning response of Mg at the micron scale.

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