Rheology of ε-iron up to 19 GPa and 600 K in the D-DIA

Abstract

Stress-strain curves, i.e., relations between the differential stress and macroscopic sample strain, of polycrystalline ε-iron have been obtained at pressures of 17(±1) GPa, three different temperatures (600, 400, and 300 K), and various strain rates between 3.8 × 10-6 and 2.3 × 10-5 s-1 using the deformation-DIA coupled with monochromatic X-rays. Five independent stress-strain curves were obtained on axial shortening and the sample exhibited ductile behavior in all. Above 4% axial strain, sample stresses reach saturation and the sample exhibited steady-state deformation. Stress exponents at temperatures of 400 and 600 K were determined to be ∼31 and ∼7, respectively. These results indicate that ε-iron deforms in plasticity regime below 400 K and that the dominant deformation mechanism at 600 K may be low temperature power-law creep. The overall deformation behavior for ε-iron is consistent with that of zinc, suggesting that the deformation mechanism map of ε-iron resembles those of other hexagonal metals. Copyright 2007 by the American Geophysical Union.