Sound velocity measurements of B2‐Fe‐Ni‐Si alloy under high pressure by inelastic X‐ray scattering: Implications for the composition of Earth's core

Elastic properties of B2-Fe0.67Ni0.06Si0.27 (15 wt.% Si) alloy have been investigated by combined high-resolution inelastic X-ray scattering and powder X-ray diffraction in diamond anvil cells up to 100 GPa at room temperature. Densities (rho), compressional (V-P) and shear (V-S) wave velocities were extrapolated to inner core conditions to enable comparison with the preliminary reference Earth model. The modeled aggregate compressional and shear wave velocities and densities of the two-phase mixture of B2-Fe0.67Ni0.06Si0.27 and hcp-Fe-Ni are consistent with inner core PREM values of V-P,V- V-S, and rho based on a linear mixing model with 30(5) vol % B2-Fe0.67Ni0.06Si0.27 and 70(5) vol % hcp Fe-Ni, which corresponds to similar to 3-5 wt.% Si and similar to 5-12 wt.% Ni.