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

  • Kinshuk Srivastava
  • Jaafar A. El-AwadyEmail author
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

In this study, atomistic simulations are utilized to quantify the effect of the \( \langle c + a\rangle \) 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 \( \langle c + a\rangle \) 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 \( \langle c + a\rangle \) dislocations show a strong plastic anisotropic behavior and the second-order pyramidal slip is limited by two singular mixed dislocation orientations at 16.78° and 42.13° with respect to the Burgers vector. Contrary to common understanding of dislocation behavior, \( \langle c + a\rangle \) 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.

Keywords

Hexagonal close-packed c-axis compression Dislocation interactions Pyramidal slip 

Notes

Acknowledgements

This research was sponsored by the Army Research Laboratory (#W911NF-12-2-0022) and by the National Science Foundation (DMR-1609533). The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of ARL or the US government.

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Copyright information

© The Minerals, Metals & Materials Society 2019

Authors and Affiliations

  1. 1.Department of Mechanical Engineering, Whiting School of EngineeringThe Johns Hopkins UniversityBaltimoreUSA

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