Some high-pressure experiments on the Fe — H system

Abstract

In situ X-ray diffraction measurements have been performed of the hydriding process of iron under high hydrogen pressure and temperatures, using a synchrotron radiation source. After hydrogénation, a sample of FeH* in equilibrium with 6 GPa of fluid H2 undergoes a sequence of phase transitions, dhcp → fee → new phase → melt, at 650 700° C, 800 900° C and 1200°C, respectively. The structure of the new hightemperature phase is tentatively identified as a defect-bec structure in which many vacancies exist in one of the simple-cubic sublattices of bcc-Fe. © 1993 R. Oldenbourg Verlag