Molecular dynamics study of fatigue behavior of nickel single-crystal under cyclic shear deformation and hyper-gravity condition

YD Xiao and XJ Deng and YW Ma and BW Huang and WY Hu, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 30, 055006 (2022).

DOI: 10.1088/1361-651X/ac6e7b

Dynamic mechanical properties play an essential role in governing the intrinsic fatigue behavior of superalloys. In this work, 001(010), 110(-110), and 101(010) pre-existing center cracks model of nickel single crystals under increasing cyclic shear deformations were studied by molecular dynamics simulations. More importantly, we introduced three hyper-gravity forces, i.e. 3 x 10(12) g, 4 x 10(12) g, and 5 x 10(12) g, during the fatigue deformation to simulate the high-speed rotation of the blade. The stress intensity factor for the first dislocation nucleation indicates that the critical stress is strongly dependent on the hyper-gravity intensities and temperatures. The fatigue life decreased rapidly with the elevated hyper-gravity strength. Moreover, the 001(010) crack propagation shows a brittle-to-ductile transition at temperatures below 300 K and is suppressed at high temperatures. The crack length in the relation to hyper-gravity intensities is discussed and shows anisotropy along the direction of hyper-gravity. No crack propagation is observed in 110(-110) and 101(010) central crack models.

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