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

• Published in: Scientific reports 2023-02, Vol.13 (1), p.2173-2173, Article 2173
• Main Authors: Vasilev, Evgenii, Popov, Dmitry, Somayazulu, Maddury, Velisavljevic, Nenad, Knezevic, Marko
• Format: Article
• Language: English
• Subjects: 639/166; 639/301; Ambient temperature; Crystals; Diamond anvil cell; Diffraction; ENGINEERING; High pressure; High pressure testing; Humanities and Social Sciences; Magnesium; MATERIALS SCIENCE; multidisciplinary; Phase transformations; Plasticity; Powder; Pressure; Science; Science (multidisciplinary); Single crystals
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-29424-z

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.