Ad
dition of solutes such as
lithium enhances ducti
lity of hexagonal-close-packed (hcp) magnesium (Mg). However, the atomistic underpinning of Li ad
dition on in
dividual deformation mechanisms remain unclear and is the focus of the present work. We compared the deformation mechanisms in nanocrystal
line (NC) and single crystal simulation systems of pure Mg and Mg-Li hcp alloys. Five deformation modes are observed in the pure NC Mg with randomly oriented grains – one basal
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lip systems
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lineImage" height="19" width="56" alt="View the MathML source" title="View the MathML source" src="/sd/grey_pxl.gif" data-inlimgeid="1-s2.0-S0927025616304402-si15.gif">. Distributing 10 at.% Li randomly to this NC Mg decreased its compressive yield strength by 14.5%. This also increases the ducti
lity by activating non-basal deformation modes and by reducing the plastic anisotropy. We benchmarked these results by comparing the effect of Li ad
dition on these deformation modes in Mg single crystals. Finally, we present a formabi
lity parameter (
lick to view the MathML source">Fp) model based on unstable stacking fault energy, twin fault energy, and nucleation stress for
dislocations (
lick to view the MathML source">τNS). Quantifying the changes in
lick to view the MathML source">Fp values for the Mg-Li alloys with respect to pure Mg in single crystal simulations explain the decrease in compressive yield strength and change in deformation mechanisms with Li ad
ditions. A sensitivity analysis study, comparing our CD-EAM results with a MEAM potential, shows that the effects of Li on the single deformation mechanisms are potential independent. Lastly, while results for Mg-10 at.% Li random alloy are presented here, similar conclusions can be drawn for other compositions of this hcp Mg-Li alloy.