The effects of ruthenium on the phase stability of fourth generation Ni-base single crystal superalloys

Sato, Atsushi; Harada, Hiroshi; Yokokawa, Toshio; Murakumo, T.; Koizumi, Yutaka; Kobayashi, Toshiharu; Imai, Hachiro

doi:10.1016/j.scriptamat.2006.01.003

Cited by 175 publications

(61 citation statements)

References 4 publications

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“…However, the addition of Re is limited by the highly increased susceptibility to form brittle and harming TCP-phases. To overcome this problem, the most recent alloy development led to the addition of Ru, which appears to be advantageous through microstructure stabilization with respect to TCP-formation [3][4][5][6][7][8][9][10][11]. However, additions of the elements Re and Ru also give rise to economic concerns, since both elements are short in availability and thus also fairly expensive.…”

Section: Introductionmentioning

confidence: 99%

Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys

Heckl

Rettig

Singer

2011

AMR

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Abstract. The influence of Re and Ru on creep rupture strength has been investigated using a new in-house designed alloy-series comprising 9 experimental nickel-base superalloys with stepwise increased Re and Ru additions. The presented creep data reveals a significant increase in creep rupture strength by additions of Re. For additions of Ru an increase of creep rupture strength can only be found for low Re contents. The present article, which is part of an extensive and systematic investigation on Re and Ru influences, shows, that an improved creep resistance by an influence of Re and Ru on the γ'-solvus temperature is rather improbable. Likewise, the influence of Re and Ru on liquidus temperature is not expected to play an important role. However, the creep rupture strength is suggested to be highly modified by γ/γ'-microstructure changes.

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Section: Introductionmentioning

confidence: 99%

Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys

Heckl

Rettig

Singer

2011

AMR

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“…4,[9][10][11] Recently, an increase in microstructural stability of the nickel based superalloys upon TCP phases formation has been achieved by the addition of Ru, resulting in the enhancement of the creep strength. 12,13) Intensive researches are being conducted concerning the role of Ru as a new potent alloying element in the next generation of the single crystal nickel based superalloys. [14][15][16][17][18] The interdiffusion of refractory elements in Ni based superalloys is a field of interest since it is important in explaining the beneficial effect of these elements on high temperature processes.…”

Section: Introductionmentioning

confidence: 99%

Diffusion and γ′ Phase Coarsening Kinetics in Ruthenium Containing Nickel Based Alloys

et al. 2008

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The present paper reports the interdiffusion of Re, W, Ru and Co in the binary and pseudo-binary Ni based alloys at 1523 K and the 0 phase coarsening kinetics of model superalloys at 1324 K. Both Re and W concentration gradients caused Ru uphill diffusion in the respective pseudo-binary diffusion couple, whereas Ru concentration gradient promoted uphill diffusion for W but not for Re. Interestingly, Re uphill diffusion occurred under the influence of Co concentration gradient but the reverse effect was not observed. The cross interdiffusion coefficients qualitatively determined from the uphill diffusion profiles were in reasonable agreement with those reported previously. Comparison of the interdiffusion coefficients in the binary and the pseudo-binary diffusion couples showed that Ru and W decreased the diffusivity of each other whereas Co appeared to be more powerful barrier atoms than Ru to decrease the Re diffusivity. Furthermore, it was evident that the coarsening kinetics of the 0 phase in both Ru-free and Ru-containing model superalloys were controlled by diffusion and Ru was found to have no effect on the rate constant of the 0 phase coarsening.

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“…Another study has proposed that an addition of around 2 wt. % Ru to the alloy will reduce the TCP precipitation rate [14]. In Fe-Ni-based poly-crystal superalloys such as IN718, it is no longer the γ -phase which acts as primary strengthener.…”

Section: Other Phasesmentioning

confidence: 99%

On Thermomechanical Fatigue of Single-Crystal Superalloys

Segersäll¹

2014

Linköping Studies in Science and Technology. Dissertations

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Thesis cover: Design by Maria J. SegersällPrinted by: LiU-Tryck, Linköping, Sweden, 2014 ISBN 978-91-7519-211-6 ISSN 0345-7524 Distributed by: Division of Engineering Materials, Department of Management and Engineering Linköping University SE-58183, Linköping, Sweden © 2014 Mikael SegersällThis document was prepared with L A T E X, October 17, 2014 AbstractThanks to their excellent mechanical and chemical properties at temperatures up to 1000°C, nickel-based superalloys are used in critical components in high-temperature applications such as gas turbines and aero engines. One of the most critical components in a gas turbine is the turbine blade, and to improve the creep and fatigue properties of this component, it is sometimes cast in single-crystal form rather than in the more conventional polycrystalline form. Gas turbines are most commonly used for power generation and the turbine efficiency is highly dependent on the performance of the superalloys.Today, many gas turbines are used as a complement for renewable energy sources, for example when the wind is not blowing or when the sun is not shining, which means that the turbine runs differently compared to earlier, when it ran for longer time periods with a lower number of start-ups and shutdowns. This new way of running the turbine, with an increased number of start-ups and shut-downs, results in new conditions for critical components, and one way to simulate these conditions is to perform thermomechanical fatigue (TMF) testing in the laboratory. During TMF, both mechanical strain and temperature are cycled at the same time, and one fatigue cycle corresponds to the conditions experienced by the turbine blade during one start-up and shut-down of the turbine engine.In the work leading to this PhD thesis, TMF testing of single-crystal superalloys was first performed in the laboratory and this was then followed microstructure investigations to study the occurring deformation and damage mechanisms. Specimens with different crystallographic directions have been tested in order to investigate the anisotropic behaviour shown by these materials. Results show a significant orientation dependence during TMF in which specimens with a low elastic stiffness perform better. However, it is also shown that specimens with a higher number of active slip systems perform better during TMF compared to specimens with less active slip sysiii tems. This is because a higher number of active slip systems results in a more widespread deformation and seems to be beneficial for the TMF life. Further, microscopy shows that the deformation during TMF is localised to several deformation bands and that different deformation and damage mechanisms prevail according to in which crystal orientation the material is loaded. Deformation twinning is shown to be a major deformation mechanism during TMF and the interception of twins seems to trigger recrystallization. This is certainly negative for the mechanical properties of single-crystal superalloys since no grain boundary strengthening elemen...

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The effects of ruthenium on the phase stability of fourth generation Ni-base single crystal superalloys

Cited by 175 publications

References 4 publications

Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys

Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys

Diffusion and γ′ Phase Coarsening Kinetics in Ruthenium Containing Nickel Based Alloys

On Thermomechanical Fatigue of Single-Crystal Superalloys

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The effects of ruthenium on the phase stability of fourth generation Ni-base single crystal superalloys

Cited by 175 publications

References 4 publications

Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys

Creep Rupture Strength of Re and Ru Containing Experimental Nickel-Base Superalloys

Diffusion and &gamma;&prime; Phase Coarsening Kinetics in Ruthenium Containing Nickel Based Alloys

On Thermomechanical Fatigue of Single-Crystal Superalloys

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Diffusion and γ′ Phase Coarsening Kinetics in Ruthenium Containing Nickel Based Alloys