Elastic constants and anisotropy in FeNi alloys at high pressures from first-principles calculations

• The single-crystal and polycrystalline elastic constants and the elastic anisotropy in face-centered cubic and hexagonal close-packed FeNi alloys have been investigated at ultrahigh pressures by means of first-principles calculations using the exact muffin-tin orbitals method and the coherent-potential approximation. Comparisons with earlier calculations for pure Fe and experimental results are presented and discussed. We show that Ni alloying into Fe increases slightly the density and has very little effect on bulk moduli. Moreover, the relative decrease in c(44) elastic constant is much stronger in the hcp phase than in the fcc one. It is found that the elastic anisotropy is higher for face-centered cubic than for the hexagonal close-packed structure of FeNi, even though the face-centered cubic phase has a higher degree of symmetry. The anisotropy in face-centered cubic structure decreases with increasing nickel concentration while a very weak increase is observed for the hexagonal close-packed structure.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

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

Nyckelord

CPA calculations

density functional theory

elastic constants

elastic

moduli

high-pressure effects

iron alloys

linear muffin-tin orbital

method

nickel alloys

earths inner-core

centered-cubic iron

generalized gradient

approximation

situ x-ray

free-energy

transition-metals

binary-alloys

hcp-iron

300 gpa

phase

Physics

NATURAL SCIENCES

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