The mechanism of hcp-bcc phase transformation in Mg single crystal under high pressure

JN Zhou and YF Guo and JY Ren and XZ Tang, SCRIPTA MATERIALIA, 236, 115670 (2023).

DOI: 10.1016/j.scriptamat.2023.115670

The mechanism of phase transformation from hexagonal close-packed (hcp) to body-centered-cubic (bcc) structure in Mg single crystal under high pressure is studied by molecular dynamics (MD) simulations. The hcpbcc phase transformation is achieved by a shear-shuffle mechanism, through the formation of bcc nanotwinned structure and the subsequent detwinning. The nanotwinned structure can effectively accommodate the shear caused by the hcp-bcc phase transformation, which facilities the growth of bcc phase under hydrostatic pressure. The detwinning turns the bcc nanotwinned structure into bcc nano-polycrystalline. Two twinning modes with the opposite twinning shear occur during the detwinning, which can accommodate the shear in different directions. The mechanism of hcp-bcc phase transformation revealed in this work brings out a comprehensive understanding of the plastic mechanism under high pressure, which is helpful for the further materials design under high pressure.

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