Elastic properties of iron-rich hcp Fe-Mg alloys up to Earth's core pressures

• Using density functional theory formulated within the framework of the exact muffin-tin orbital method, we investigate the elastic properties of hexagonal closed-packed Fe-Mg alloys, containing 5 and 10 at.% Mg, up to pressures of the Earth's inner core. We demonstrate the effect of Mg alloying on the hexagonal axial ratio, elastic constants, density and sound wave velocities. We find that 10% Mg alloying decreases the shear modulus of iron by 23% and reduces the transverse sound velocity, nu(s) by 12% at core pressures. Although it is debated whether or not Mg can partition into the core, our results support Mg as a candidate light element in the core.

Subject headings

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Keyword

ab initio

elasticity

pressure

Earth's inner core

centered-cubic iron

inner-core

x-ray

thermal-expansion

potential

model

ab-initio

in-situ

approximation

temperature

transition

Physics

Publication and Content Type

ref (subject category)

art (subject category)