Lattice parameters of Ni(γ), Ni3Al(γ') and Ni3Ga(γ') solid solutions with additions of transition and B-subgroup elements

Mishima, Yoshinao; Ochiai, Shouichi; Suzuki, Tomoo

doi:10.1016/0001-6160(85)90211-1

Cited by 262 publications

(118 citation statements)

References 40 publications

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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.…”

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confidence: 68%

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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confidence: 68%

Direct Lattice Parameter Measurements Using HAADF-STEM

et al. 2014

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“…An example for a "stabilized" ternary Laves phase is Ta(Ni,Al) 2 , [9] i.e. both, TaNi 2 and TaAl 2 , do not form Laves phases.…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Valence Electron Concentration on the Structural Variation of the Laves Phases MgNi_2–xGe_x

Siggelkow

Hlukhyy

Fässler

2017

Zeitschrift anorg allge chemie

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Abstract. The influence of the partial substitution of Ni atoms by the similarly sized but electron-richer Ge atoms with a similar electronegativity in the binary Laves phase MgNi 2 is investigated. A small degree of substitution in MgNi 2-x Ge x (x = 0.1) leads to the change of the hexagonal MgNi 2 -type structure (C36) to the cubic C15 type, whereas higher amounts of Ge lead to the formation of the two new Laves phases Mg 2 Ni 3 Ge and MgNi 1.30(5) Ge 0.70 , which were synthesized by the direct reaction of the elements in alumina and niobium crucibles using an induction furnace. The crystal structures of the two phases were determined by single-crystal X-ray diffraction. Mg 2 Ni 3 Ge (hR18-MgNi 2-x Ge x , x = 0.5) crystallizes in the Y 2 Rh 3 Ge-type structure, which

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“…The lattice parameter of Ni 3 Al has been reported to be 0.357 nm, 2125) which is close to that in present study. Mishima et al 20) have studied the lattice parameter changes in Ni 3 Al with transition and B-subgroup elements addition; based on a linear relation between lattice constant and concentration of constituent at constant temperature, Vegard's Law was proposed for the prediction of £ A lattice parameter in Ni-based superalloys. The value of a £ A is taken as 0.357 nm and the Vegard's coefficients of alloying elements for £ A phase was obtained as the following formulae:…”

Section: Microstructure and Composition Analysismentioning

confidence: 99%

“…Co, Cr, Ta and W are chosen for alloying with Ni 3 Al in present work. From previous studies on the site preference of ternary additions in Ni 3 Al, 19,20) it has been known that Ta and W substitute for Al site; Co and Cr prefer substituting for Ni site. Nevertheless, these studies only focus on small amount of alloying in Ni 3 Al.…”

Section: Introductionmentioning

confidence: 99%

The Thermal Stability and Strength of Highly Alloyed Ni<sub>3</sub>Al

Tsao

Yeh

2015

Mater. Trans.

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In this study the L1 2 gamma prime phase (based on Ni 3 Al) has been highly alloyed with Cr, Co, W, and Ta in order to examine the effects on strengthening and thermal stability. The order-disorder transition temperature of gamma prime is decreased with higher alloying content. Thermodynamic calculations show that the ordering enthalpy decreases as the entropy term increases. Conversely, the hardness can be 1.5 times higher comparing to that of a conventional Ni-based superalloy. This indicates that the strengthening effect of designing a gamma prime composition toward higher entropy is significant, due to greater lattice distortion and higher anti-phase boundary energy of gamma prime.

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Lattice parameters of Ni(γ), Ni3Al(γ') and Ni3Ga(γ') solid solutions with additions of transition and B-subgroup elements

Cited by 262 publications

References 40 publications

Direct Lattice Parameter Measurements Using HAADF-STEM

Direct Lattice Parameter Measurements Using HAADF-STEM

The Influence of the Valence Electron Concentration on the Structural Variation of the Laves Phases MgNi_2–xGe_x

The Thermal Stability and Strength of Highly Alloyed Ni<sub>3</sub>Al

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Lattice parameters of Ni(γ), Ni3Al(γ') and Ni3Ga(γ') solid solutions with additions of transition and B-subgroup elements

Cited by 262 publications

References 40 publications

Direct Lattice Parameter Measurements Using HAADF-STEM

Direct Lattice Parameter Measurements Using HAADF-STEM

The Influence of the Valence Electron Concentration on the Structural Variation of the Laves Phases MgNi2–xGex

The Thermal Stability and Strength of Highly Alloyed Ni<sub>3</sub>Al

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The Influence of the Valence Electron Concentration on the Structural Variation of the Laves Phases MgNi_2–xGe_x