The body-centered cubic Fe phase under extreme conditions: Observed yet unnoticed.

The recently disclosed mechanism of the body-centered cubic Fe stabilization under extreme pressures and temperatures allows for a new interpretation of a number experimental observations. The high-PT bcc Fe is stabilized by a liquid-like self-diffusion. This means that Fe at high pressure and temperatures is in many respects similar to liquid. Such similarity is confusing to some experimentalists and makes them to interpret solid-solid hcp-bcc transition as melting. I will demonstrate that a number of experimental data sets get a better explanation in terms of the hcp-bcc transition rather than in terms of hcp-liquid transition. The new interpretation removes a number of controversies concerning the extreme part of Fe phase diagram. I will show that in a number of experiments the bcc Fe was observed yet remained unnoticed because of the unexpected properties of the emerging high-PT Fe bcc phase.