First-principles calculations for the elastic properties of Ni-base model superalloys: Ni/Ni3Al multilayers |
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Authors: | Wang Yun-Jiang and Wang Chong-Yu |
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Institution: | Department of Physics, Tsinghua University, Beijing
100084, China |
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Abstract: | A model system consisting of Ni001](100)/Ni3Al001](100)
multi-layers are studied using the density functional theory in order to
explore the elastic properties of single crystal Ni-based
superalloys. Simulation results are consistent with the experimental
observation that rafted Ni-base superalloys virtually possess a
cubic symmetry. The convergence of the elastic properties with
respect to the thickness of the multilayers are tested by a series
of multilayers from 2γ'+2γ to 10γ'+10γ
atomic layers. The elastic properties are found to vary little with
the increase of the multilayer's thickness. A Ni/Ni3Al
multilayer with 10γ'+10γ atomic layers (3.54 nm) can
be used to simulate the mechanical properties of Ni-base model
superalloys. Our calculated elastic constants, bulk modulus,
orientation-dependent shear modulus and Young's modulus, as well as
the Zener anisotropy factor are all compatible with the
measured results of Ni-base model superalloys R1 and the advanced
commercial superalloys TMS-26, CMSX-4 at a low temperature. The
mechanical properties as a function of the γ' phase volume
fraction are calculated by varying the proportion of the γ and
γ' phase in the multilayers. Besides, the mechanical
properties of two-phase Ni/Ni3Al multilayer can be well
predicted by the Voigt-Reuss-Hill rule of mixtures. |
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Keywords: | Ni-based superalloys Ni/Ni3Al multilayer mechanical property first principles rule of mixture |
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