Shock consolidation and spallation in nanopowdered Mg: Contributed by deformation twinning and disordering

MY Wang and D He and W Bi and M Shang and Y Cai and L Deng and X Zhang and F Zhao and J Tang and L Wang, JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY, 224, 105-124 (2025).

DOI: 10.1016/j.jmst.2024.10.041

Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials, and a thorough investigation of the deformation and its underlying mechanisms in consolidation is of great engineering significance. We conduct non-equilibrium molecular dynamics (NEMD) simulation and X-ray diffraction (XRD) simulation to systematically study shockinduced deformation and the corresponding mechanisms during the consolidation of nanopowdered Mg (NP-Mg). Two different deformation modes govern the shock consolidation in NP-Mg, i.e., deformation twinning at up <= 1.5 km s-1 and structural disordering, at up >= 2.0 km s-1 . They accelerate the collapse of nanopores and void compaction, giving rise to the final consolidation of NP-Mg. Three types of deformation twinning are emitted in NP-Mg, i.e., the extension twinning for 112 1 (1 1 26 ) , and 11 02 (1 1 01 ) , and the compression 112 2 (1 1 23 ) twinning. They are prompted via coupling atomic shuffles and slips. Deformation twinning prefers to occur within the grains as shock along (112 0 ) or its approaching direction (A- and B-type grains), originated from the high-angle grain boundaries (HAGB) at compression stage. They are inhibited within the ones as shocking along (0 0 01 ) and the approaching ones (C- and D -type grains). The release and tension loading facilitates the reversible and irreversible detwinning, for the extension and compression twinning, respectively, within the A- and B-type grains. It also contributes to a compression-tension asymmetry for twinning, i.e., release and tension induced extension twinning within the C- and D -type grains. The subsequent spallation is mediated by GB sliding and GB-induced stacking faults at up <= 1.5 km s-1 , and structural disordering at up >= 2.0 km s-1 . (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

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