The Effect of the Orientation of Second-Order Pyramidal < c plus a > Dislocations on Plastic Flow in Magnesium

K Srivastava and JA El-Awady, MAGNESIUM TECHNOLOGY 2019, 305-310 (2019).

DOI: 10.1007/978-3-030-05789-3_45

In this study, atomistic simulations are utilized to quantify the effect of the hcthornai dislocation orientation on the critical resolved shear stress and mechanism of glide on second-order pyramidal planes in pure Mg. The studied orientations are those where the crystallographic periodicities along the dislocation line are less than about three times the hcthornai Burgers vector magnitude. The simulations results show a sharply anisotropic response for the critical resolved shear with dislocation orientations, which indicates a much complex picture of plasticity in Mg than previously thought. The current results also show that the hcthornai dislocations show a strong plastic anisotropic behavior and the second-order pyramidal slip is limited by two singular mixed dislocation orientations at 16.78 degrees and 42.13 degrees with respect to the Burgers vector. Contrary to common understanding of dislocation behavior, hcthornai slip in Mg is quite complex and coarse- grained models like DDD simulations that rely solely on edge and screw dislocation mobilities are therefore insufficient in capturing the plastic flow mechanisms.

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