Observation of Fundamental Mechanisms in Compression-Induced Phase Transformations Using Ultrafast X-ray Diffraction

Michael R. Armstrong, Harry B. Radousky, Ryan A. Austin, Elissaios Stavrou, Hongxiang Zong, Graeme J. Ackland, Shaughnessy Brown, Jonathan C. Crowhurst, Arianna E. Gleason, Eduardo Granados, Paulius Grivickas, Nicholas Holtgrewe, Hae Ja Lee, Tian T. Li, Sergey Lobanov, Joseph T. McKeown, Bob Nagler, Inhyuk Nam, Art J. Nelson, Vitali PrakapenkaClemens Prescher, John D. Roehling, Nick E. Teslich, Peter Walter, Alexander F. Goncharov, Jonathan L. Belof

Research output: Contribution to journalArticlepeer-review

Abstract

As theoretically hypothesized for several decades in group IV transition metals, we have discovered a dynamically stabilized body-centered cubic (bcc) intermediate state in Zr under uniaxial loading at sub-nanosecond timescales. Under ultrafast shock wave compression, rather than the transformation from alpha-Zr to the more disordered hex-3 equilibrium omega-Zr phase, in its place we find the formation of a previously unobserved nonequilibrium bcc metastable intermediate. We probe the compression-induced phase transition pathway in zirconium using time-resolved sub-picosecond x-ray diffraction analysis at the Linac Coherent Light Source. We also present molecular dynamics simulations using a potential derived from first-principles methods which independently predict this intermediate phase under ultrafast shock conditions. In contrast with experiments on longer timescale (> 10 ns) where the phase diagram alone is an adequate predictor of the crystalline structure of a material, our recent study highlights the importance of metastability and time dependence in the kinetics of phase transformations.
Original languageEnglish
Pages (from-to)1-9
Number of pages9
JournalJOM
DOIs
Publication statusPublished - 12 Jan 2021

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