Atomic simulations on the deformation mechanisms in nano-crystalline Ni- Al series Ni-based superalloy based on grain size, strain rate and temperature

HC Dong and TH Xu and TY Ning and M Liu and DY Wu and HK Ma and ZH Feng and B Narayanaswamy and R Su and T Wang, JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T, 23, 77-89 (2023).

DOI: 10.1016/j.jmrt.2022.12.183

Molecular Dynamic (MD) simulations were used to investigate the tensile properties of nanocrystalline Ni-Al series Ni-based superalloy at different grain sizes (6.54-20 nm), strain rates (1 x 107-5 x 108 s-1) and temperatures (300-1000 K). Results indicate that plastic deformation of nanocrystalline Ni-Al series Ni-based superalloy was governed by stacking faults and FCC-to-HCP martensitic phase transformation, which was significantly different from twinning-dominated plastic deformation in nanocrystalline Ni. Neverthe-less, the conventional Hall-Petch breakdown occurred at a critical grain size in both nanocrystalline Ni and Ni-Al series Ni-based superalloy. Moreover, the critical mean grain size was little influenced by the strain rate in the strain-rate range of 107 to 5 x 108 s-1. Strain rate sensitivity m was closely related to grain size and strain rate. Grains combi-nation can be observed at lower strain rate, while at higher strain rate, GB diffusion was visible. Besides, flow stress and Young's modulus were both strongly affected by temper-ature, and an increase in temperature can accelerate GB diffusion and GB migration. The current study provides an atomic perspective on the deformation process and mechanisms in nanocrystalline Ni-Al series Ni-based superalloy, as well as new perspectives on designing novel superalloys with excellent mechanical properties.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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