Simulations of dislocation mobility in magnesium from first principles
I Shin and EA Carter, INTERNATIONAL JOURNAL OF PLASTICITY, 60, 58-70 (2014).
The strength and ductility of metals are governed by the motion of dislocations, which is quantified by the Peierls stress (sigma(p)). We use orbital-free density functional theory (OFDFT) to characterize the motion of 1/3 < 11 (2) over bar0 > dislocations on the basal 0001 and prismatic 1 (1) over bar 00 planes in hexagonal-close-packed magnesium (Mg) in order to understand its deformation mechanisms. We predict sigma(p) values of edge dislocations on the basal and prismatic planes to be 0.6 and 35.4 MPa, respectively. The presence of stable stacking faults only on the basal plane produces partial dislocation splitting, which significantly lowers sigma(p) for basal dislocations. Our atomic scale simulations reveal that dislocation mobility is strongly correlated with the number of core atoms moving collectively. OFDFT sigma(p) results are in excellent agreement with experiments (similar to 0.5 and 39.2 MPa), further validating OFDFT as an independent and predictive tool for simulating plastic behavior in main group metals at the mesoscale with first principles' accuracy. (C) 2014 Elsevier Ltd. All rights reserved.
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