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

• Published in: Geophysical research letters Vol. 34; no. 23
• Main Authors: Nishiyama, Norimasa, Wang, Yanbin, Rivers, Mark L., Sutton, Steve R., Cookson, David
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 16.12.2007; American Geophysical Union
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; hcp-iron; pressure; rheology; strain; strain rates; rheology; maps; X-rays; metals; creep; plasticity; exhibits; pressure; low temperature; Stress strain; saturation; temperature; iron; Power law; zinc; Strain rate
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2007GL031431

Stress‐strain curves, i.e., relations between the differential stress and macroscopic sample strain, of polycrystalline ɛ‐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 ɛ‐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 ɛ‐iron is consistent with that of zinc, suggesting that the deformation mechanism map of ɛ‐iron resembles those of other hexagonal metals.