Local lattice distortion mediated formation of stacking faults in Mg alloys

William Yi Wang, Bin Tang, Shun Li Shang, Jiangwei Wang, Shilei Li, Yi Wang, Jian Zhu, Siyuan Wei, Jun Wang, Kristopher A. Darling, Suveen N. Mathaudhu, Yiguang Wang, Yang Ren, Xi Dong Hui, Laszlo J. Kecskes, Jinshan Li, Zi Kui Liu

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Long periodic stacking ordered phases (LPSOs), consisting of various configurations of stacking faults, play an important role in developing ultrastrong Mg alloys with moderate ductility. However, their formation mechanisms are far from clear as no apparent defects are introduced during their formation as it is commonly believed that stacking faults are induced by defects. Here, we present the atomic and electronic basis for lattice-distortion-mediated formation of stacking faults, i.e., localized face-centred-cubic (FCC) structures, within a Mg-Zn-Y alloy with a hexagonal close-packed (HCP) structure. The atomic motion trajectories from ab-initio molecular dynamic simulations show that the Mg atoms occupying the nearest neighbour positions of Zn and Y solute atoms undergo a local HCP-to-FCC transition. It is revealed that a local lattice distortion caused by the solute atoms enables the Mg atoms to move and rearrange into a local FCC configuration, which is validated by high resolution scanning transmission microscopy and in-situ synchrotron X-ray diffraction. Our simulations provide profound insight into the formation mechanism of stacking faults in HCP Mg and their physical nature of phase transformations. This is not only critically important because conventional defects, such as dislocations and vacancies, are important to deformation for Mg and its alloys, but also because they serve as a potential new approach to the design of advanced Mg alloys when defects could be used to facilitate.

Original languageEnglish (US)
Pages (from-to)231-239
Number of pages9
JournalActa Materialia
Volume170
DOIs
StatePublished - May 15 2019

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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    Wang, W. Y., Tang, B., Shang, S. L., Wang, J., Li, S., Wang, Y., Zhu, J., Wei, S., Wang, J., Darling, K. A., Mathaudhu, S. N., Wang, Y., Ren, Y., Hui, X. D., Kecskes, L. J., Li, J., & Liu, Z. K. (2019). Local lattice distortion mediated formation of stacking faults in Mg alloys. Acta Materialia, 170, 231-239. https://doi.org/10.1016/j.actamat.2019.03.030