2:15 PM - 2:30 PM
[SIT22-27] Effect of silicon on viscosity of ε-iron
We conduct in situ high pressure experiments to determine the relative viscosity between pure iron and Si alloying iron at the stability field of ε-iron iron. We used polycrystalline Si-free and 3 wt % bearing irons couple as starting material. In the high pressure experiment, the starting materials was compressed in a cubic type high pressure cell in a deformation-DIA type apparatus at BL04B1, Spring-8. At the pressure of ~5 GPa, sample was repeatedly heated to ~1000 K and quenched to room temperature across the phase boundary between bcc and fcc iron to obtain the equigranular texture due to phase change. Then subsequently sample was deformed at ~12 GPa with ε-iron structure. Stress and strain were measured by X-ray diffraction and X-ray radiography, respectively.
Preliminary results suggest that the effect of silicon on viscosity is small, indicated by the comparable strain between Si-free and 3 wt % bearing irons at the experimental condition, strain rate of 10-3-10-4 /s, stress level of ~1 GPa and strain up to ~10 %. If we simply apply this preliminary result, the variation in the observed seismic attenuation may not be explained by alloying by silicon and alternative such as partial melting or pre-melting should be considered.