Alloying element additions to Ni3Al: Site preferences and effects on elastic properties from first-principles calculations

Ni3Al-based superalloys have excellent mechanical properties which have been widely used in civilian and military fields. In this study, the mechanical properties of the face-centred cubic structure Ni3Al were investigated by a first principles study based on density functional theory (DFT), and the generalized gradient approximation (GGA) was used as the exchange-correlation function. The bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio of Ni3Al polycrystal were calculated by Voigt-Reuss approximation method, which are in good agreement with the existing experimental values. Moreover, directional dependences of bulk modulus, Young’s modulus, shear modulus and Poisson’s ratio of Ni3Al single crystal were explored. In addition, the thermodynamic properties (e.g., Debye temperature) of Ni3Al were investigated based on the calculated elastic constants, indicating an improved accuracy in this study, verified with a small deviation from the previous experimental value.

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“…In addition, the three-dimensional surface of the shear modulus of Ni 3 Al can be expressed by Equation (25) [51]:…”

Section: Elastic Anisotropymentioning

confidence: 99%

The Mechanical Properties and Elastic Anisotropies of Cubic Ni3Al from First Principles Calculations

et al. 2018

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“…A histogram of the third and fourth nearest-neighbor distances calculated from the HAADF-STEM images is presented in Figure 2. The lattice parameter measurements using RevSTEM images acquired from each of the three phases are consistent with the expected trend a(Ni 3 Al) > a(NiAlCr γ') > a(NiAlCr γ) [3][4]. Extending the approach, we will demonstrate the power of the technique to accurately measure lattice parameter and strain across the γ/ γ ' interface.…”

mentioning

confidence: 73%

Direct Lattice Parameter Measurements Using HAADF-STEM

et al. 2014

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Lattice strain is generated in crystal structures as a result of atomic size differences between host atom and solute elements during substitutional alloying. Extensive work has been performed to study lattice parameter variation with alloying elements, primarily using diffraction methods. The global information provided by reciprocal space analysis, however, limits access to local structural details. In contrast, atomic resolution STEM enables direct imaging of the crystal structure, but drift distortion currently limits capabilities to measure lattice parameters. This is particularly relevant for Ni-based superalloys as the microstructure consists of cuboidal intermetallic γ' phase precipitate (L1 2 structure) within a γ phase matrix (FCC structure). As the coherent γ/ γ ' interface is responsible for limiting dislocation motion [1], direct measurement of lattice parameters and strain provides critical information to further next generation alloy design.In this presentation, we will report direct lattice parameter measurements in annealed single-crystal Ni-based superalloys using a probe-corrected scanning transmission electron microscope (FEI Titan 60-300 S/TEM). We will show that picometer precision and accuracy are enabled by the newly developed RevSTEM technique [2]. Peak locations are determined using a normalized cross correlation approach and 2D Gaussian peak fitting [2] to enable the measurement of atom column separations. RevSTEM-processed HAADF-STEM images for pure Ni 3 Al, γ' phase NiAlCr and γ phase NiAlCr in the <100> projection are shown in Figure 1. A histogram of the third and fourth nearest-neighbor distances calculated from the HAADF-STEM images is presented in Figure 2. The lattice parameter measurements using RevSTEM images acquired from each of the three phases are consistent with the expected trend a(Ni 3 Al) > a(NiAlCr γ') > a(NiAlCr γ) [3][4]. Extending the approach, we will demonstrate the power of the technique to accurately measure lattice parameter and strain across the γ/ γ ' interface. Overall, these results open a new realm of atomic scale structure analysis that was previously just beyond our reach due to drift [2].

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“…Thus the effects of M (Ti, Nb) added into the Ni3Al have been studied in the experiments and the theoretical calculations as above. Unfortunately, previous studies had been conducted to research elastic properties of Ni3Al-M (Ti, Nb) ternary alloys, and few reported electronic structure of M (Ti, Nb) in Ni3Al alloy, such as Soga [6] and Q. Wu [8]. In this work, the site preferences of the alloying elements X in Ni3Al and elastic properties of Ni3Al alloys are predicted with the firstprinciples theory.…”

Section: Introduction mentioning

confidence: 90%

Ti and Nb Addition to Ni3Al: Site Preferences and Alloying Efficiency from First Principles Calculations

Haiguang

Huang

Zhang

et al. 2017

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The first principles calculations were performed to investigate site preferences of the alloying elements M (Ti, Nb) doping in Ni3Al, elastic properties and the electronic structure of Ni3Al and Ni3Al-M with the Cambridge sequential total energy package (CASTEP). It was found that M were preferred to replace the Al sites. As the M doping. The bulk, shear and Young's modulus increased and the bulk/shear modulus ratios (B/G) decreased in Ni3Al polycrystalline alloy. While B/G of all alloys were larger than 1.75, signifying that Ni3Al, Ni24Al7Nb and Ni24Al7Ti polycrystalline alloys possessed ductility. Analyzing the electronic structure of Ni3Al and Ni3Al-M, the results showed that the main interaction between the Ni atoms and the Al atoms was covalence in the Ni3Al, after doping elements M (Ti, Nb) in Ni3Al, there was strong orbital hybridization between the Al-3p orbital, Ni-3d orbital and M-d (Ti-3d, Nb-4d) orbital, the covalent bonds between alloying atoms M (Ti, Nb) and their neighbor atoms Ni were stronger than that between Al atom and Ni atom.

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Alloying element additions to Ni3Al: Site preferences and effects on elastic properties from first-principles calculations

Cited by 135 publications

References 50 publications

The Mechanical Properties and Elastic Anisotropies of Cubic Ni3Al from First Principles Calculations

The Mechanical Properties and Elastic Anisotropies of Cubic Ni3Al from First Principles Calculations

Direct Lattice Parameter Measurements Using HAADF-STEM

Ti and Nb Addition to Ni3Al: Site Preferences and Alloying Efficiency from First Principles Calculations

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