Interdiffusion in MCrAlY coated nickel-base superalloys

Elsaß, Moritz; Frommherz, Martin; Scholz, Alfred; Oechsner, Matthias

doi:10.1016/j.surfcoat.2016.09.049

Cited by 60 publications

(16 citation statements)

References 12 publications

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“…The usage of Thermo‐Calc for the calculation of thermodynamic properties in nickel‐based superalloys and MCrAlY‐alloys has been proven valid numerous times in the common literature [37–42]. In a previous publication, the good agreement between a Thermo‐Calc‐Simulation and experimental data for the interdiffusion process of Bond Coat 1 and René 80 was shown [26].…”

Section: Resultsmentioning

confidence: 92%

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Temperature influence on the development of interdiffusion phenomena in MCrAlY‐coated nickel‐based superalloys

Elsaß

Kontermann

Oechsner

2021

Materialwissenschaft Werkst

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In this work, the interdiffusion between a MCrAlY‐bond coat and two different nickel‐based superalloys is evaluated at three temperatures, 950 °C, 980 °C, and 1,050 °C. Of primary interest is the evolution of Kirkendall‐porosity, the β‐depleted zone in the bond coat and the β’‐ depleted zone in the superalloy. The three phenomena arise near the interface between bond coat and superalloy as a result of interdiffusion between both materials and are detrimental to the coating‐substrate system. The evolution of the interdiffusion phenomena is highly dependent on the alloy composition of the materials as well as the annealing temperature. It has been found that not only the temperature dependency of the diffusion coefficient but also the temperature dependent element activities are an important factor when evaluating the interdiffusion phenomena. It has further been shown that at lower temperatures the amount of Kirkendall‐porosity per volume fraction is higher than at higher temperatures, even though the overall amount of porosity is lower. Different equilibrium concentrations of main alloying elements and a correspondingly lower over‐saturation of vacancies have been identified as the main explanation.

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Section: Resultsmentioning

confidence: 92%

“…The specimens for the experimental work were prepared in the same way and the same materials were used as reported in previous publications [26, 27]. Cylindrical rods consisting of the conventionally cast nickel‐based superalloys René 80 (diameter 10 mm) and CM 247 (diameter 8 mm) were coated with a NiCoCrAlYSi bond coat (BC1).…”

Section: Scientific Methodsmentioning

confidence: 99%

Temperature influence on the development of interdiffusion phenomena in MCrAlY‐coated nickel‐based superalloys

Elsaß

Kontermann

Oechsner

2021

Materialwissenschaft Werkst

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“…Since MCrAlY coatings are always utilised in with high temperature conditions (at 1000 °C or higher), the oxidation process is largely accelerated at such high temperatures, resulting in serious Al loss and β-phase depletion. Previous work mainly focuses on the oxidation kinetics, oxide growth mechanisms and interdiffusion of various MCrAlY compositions under different exposure conditions [31][32][33]. Specific temperature concerns related to the β-phase depletion kinetics have not been reported yet.…”

Section: Introductionmentioning

confidence: 99%

Effects of temperature on the β-phase depletion in MCrAlYs: A modelling and experimental study towards designing new bond coat alloys

Chen

Rushworth

Hou

et al. 2019

Surface and Coatings Technology

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This paper investigates the effects of varied temperature conditions on the kinetics of β-phase depletion in MCrAlYs by DICTRA diffusion simulations and experimental observations. A commercially available MCrAlY composition and two modelled compositions were examined at temperature regimes of 1000 °C, 1100 °C and 1200 °C. A previously developed temperature-dependent oxidation model was used at the boundary to examine the β-phase depletion kinetics at different temperatures. The oxide growth kinetics and the corresponding Al flux were calculated based on the oxidation model. The MCrAlY phase equilibrium calculations were conducted in Thermo-Calc and the oxidation-diffusion simulations were carried out using the finite difference diffusion software, DICTRA. It was found that the MCrAlYs exhibit a predominantly dual-phase γ+β structure at 1000 °C and above. It was revealed that varying the temperature had a strong effect on the β-phase depletion in low Alcontent MCrAlYs from DICTRA simulations and available experimental measurements. In *Manuscript Click here to view linked References addition, it was demonstrated from the diffusion simulations that MCrAlYs with high Al content exhibit an enhanced lifetime in maintaining the two-phase structure with less β-phase depletion at high temperatures due to the high Al and β-phase content.

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“…[28][29][30][31][32][33][34][35][36][37][38]. In these research works, the emphasis has been on oxide growth, phase transformation and element diffusion, but specific concerns on the β-phase coarsening behaviour in the MCrAlY coating have not been addressed.…”

Section: Introductionmentioning

confidence: 99%

An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy

Chen

McCartney

2017

Journal of Alloys and Compounds

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This paper investigates the β-phase coarsening behaviour during isothermal heat treatment of free-standing CoNiCrAlY (Co-31.7%Ni-20.8%Cr-8.1%Al-0.5%Y, all in wt%) coatings prepared by high velocity oxy-fuel (HVOF) thermal spraying. The microstructure of the coatings was characterised using scanning electron microscopy with energy dispersive X-ray (EDX) analysis and electron backscatter diffraction (EBSD). It comprises a two phase structure of fcc γ-Ni matrix and bcc β-NiAl precipitates. The volume fraction of the γ-Ni and the β-NiAl phases were measured to be around 70% and 30% respectively, with grain sizes varying largely from 0.5 to 2 µm for both phases. Isothermal heat treatments of the freestanding coatings were carried out at 1100 C for times up to 250 h. The β-phase coarsening behaviour during isothermal heat treatments was analysed by quantitative metallography. It is shown that the coarsening behaviour of β phase in the CoNiCrAlY alloy followed the classical Lifshitz-Slyozov-Wagner (LSW) theory of Ostwald ripening. By incorporating a dimensionless factor which correlates with volume fraction of the β phase, a modified LSW model coupled with formulaic interfacial energy and effective diffusion coefficient of the 2 CoNiCrAlY alloy was utilised to interpret the coarsening behaviour of the β phase. The coarsening rate coefficient obtained from the modified LSW model shows good agreement with the corresponding experimental result.

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Interdiffusion in MCrAlY coated nickel-base superalloys

Cited by 60 publications

References 12 publications

Temperature influence on the development of interdiffusion phenomena in MCrAlY‐coated nickel‐based superalloys

Temperature influence on the development of interdiffusion phenomena in MCrAlY‐coated nickel‐based superalloys

Effects of temperature on the β-phase depletion in MCrAlYs: A modelling and experimental study towards designing new bond coat alloys

An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy

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