Title: White Laue and powder diffraction studies to reveal mechanisms of HCP-to-BCC phase transformation in single crystals of Mg under high pressure

Abstract

Mechanisms of hexagonal close-packed (HCP) to body-centered cubic (BCC) phase transformation in Mg single crystals are observed using a combination of polychromatic beam Laue diffraction and monochromatic beam powder diffraction techniques under quasi-hydrostatic pressures of up to 58 ± 2 GPa at ambient temperature. Although experiments were performed with both He and Ne pressure media, crystals inevitably undergo plastic deformation upon loading to 40–44 GPa. The plasticity is accommodated by dislocation glide causing local misorientations of up to 1°–2°. The selected crystals are tracked by mapping Laue diffraction spots up to the onset of the HCP to BCC transformation, which is determined to be at a pressure of 56.6 ± 2 GPa. Intensity of the Laue reflections from HCP crystals rapidly decrease but no reflections from crystalline BCC phase are observed with a further increase of pressure. Nevertheless, the powder diffraction shows the formation of 110 BCC peak at 56.6 GPa. The peak intensity increases at 59.7 GPa. Upon the full transformation, a powder-like BCC aggregate is formed revealing the destructive nature of the HCP to BCC transformation in single crystals of Mg.

Authors:

Vasilev, Evgenii ^[1]; Popov, Dmitry ^[2]; Somayazulu, Maddury ^[2]; Velisavljevic, Nenad ^[3]; Knezevic, Marko ^[1]

---

+ Show Author Affiliations

1. University of New Hampshire, Durham, NH (United States)
2. Argonne National Laboratory (ANL), Argonne, IL (United States)
3. Argonne National Laboratory (ANL), Argonne, IL (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Publication Date:

Tue Feb 07 00:00:00 EST 2023

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF): US Army Research Laboratory (USARL)

OSTI Identifier:

2223020

Report Number(s):

LLNL-JRNL-855584
Journal ID: ISSN 2045-2322; 1070464

Grant/Contract Number:  

AC52-07NA27344; AC02-06CH11357; CMMI-1650641; W911NF-21-2-0149; EAR-1606856; EAR-1634415; FG02-94ER14466

Resource Type:

Accepted Manuscript

Journal Name:

Scientific Reports

Additional Journal Information:

Journal Volume: 13; Journal Issue: 1; Journal ID: ISSN 2045-2322

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 42 ENGINEERING