In situ x-ray diffraction of fast compressed iron: Analysis of strains and stress under non-hydrostatic pressure

Konopkova, Z and Rothkirch, A and Singh, AK and Speziale, S and Liermann, HP (2015) In situ x-ray diffraction of fast compressed iron: Analysis of strains and stress under non-hydrostatic pressure. Physical Review B, 91 (14). pp. 144101-1. ISSN 1098-0121

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    Series of high-pressure x-ray diffraction patterns of iron and its high-pressure polymorphs were collected with 0.1–0.2-s exposure time utilizing a membrane diamond anvil cell (DAC) for compression at various loading and unloading rates to a maximum pressure of 70 GPa. Strain rates of 10−2 s−1 at a maximum pressurization rate of 4.1 GPa/s were achieved in non-hydrostatic compression of hcp Fe. Linewidth analysis was used to retrieve strain and uniaxial stress of Fe as a function of pressure upon both compression and decompression. Analysis of the lattice parameters ratio c/a of hcp Fe indicates the presence of complex non-hydrostatic stress states, which developed as a function of strain rate, relaxation time, and various levels of hydrostaticity. Our results emphasize the importance of a controlled pressurization in DACs because the experimental loading rate strongly influences the stress state of the sample, particularly on decompression. Our time-resolved x-ray diffraction of the phase transition from bcc Fe to hcp Fe reveals residual grains of bcc Fe capable of surviving to very high pressures (>35 GPa) for a few minutes after the transition.

    Item Type: Journal Article
    Additional Information: Copyright to this article belongs to M/s. The American Physical Society
    Uncontrolled Keywords: Diamond anvil cell (DAC);Meteorite impact;Asteroid impact;X-ray diffraction;Microstrain
    Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
    Division/Department: Other, Other, Materials Science Division, Other, Other
    Depositing User: Ms. Alphones Mary
    Date Deposited: 22 May 2015 13:58
    Last Modified: 17 Aug 2015 12:04

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