Precipitation and dissolution processes in γ / γ ′ single crystal nickel-based superalloys

Grosdidier, Thierry; Hazotte, Alain; Simón, A.

doi:10.1016/s0921-5093(98)00795-3

Cited by 212 publications

(120 citation statements)

References 36 publications

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“…The detailed explanation of sample preparation and inspection is available elsewhere. [3,4,9,13] The samples identified as containing a surface defect were cut out by wire-guided electro discharge machining (EDM). The cut sample was ultrasonic-cleaned in ethanol for 5 minutes.…”

Section: Methodsmentioning

confidence: 99%

“…The solution heat treatment process undertaken on these samples was intended to dissolve the c/c¢ eutectics and reduce the chemical segregation resulting from the dendritic growth during the solidification process. [13] Therefore, even though the elongated c¢ phase might form during solidification, it would have been dissolved as the heat treatment was above the c¢ solvus, and as a result there was little possibility that the elongated c¢ phase was analogous to the columnar zone of elongated grains formed during solidification.…”

Section: A Possibility Of Cellular Recrystallization or Formation Ofmentioning

confidence: 99%

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Formation of an Intermediate Layer Between Grains in Nickel-Based Superalloy Turbine Blades

Kim

Withey

2017

Metall Mater Trans A

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The boundary region formed on the surface of nickel-based single-crystal turbine blades was investigated by high-resolution microscopy observation. There was a distinguishable intermediate layer with the size of about 2 to 5 lm between the matrix and surface defect grains such as stray grains, multiple grains, freckle grains, and even low-angle grain boundaries which were formed during the solidification of turbine blades. The intermediate layer was composed of many elongated c¢ as well as c phases. In addition, only one side of the intermediate layer was coherent to the matrix grain or defect grain due to good orientation match. At the coherent interface, the c¢ (as well as c) phase started to extend from the parent grain and coincidently, rhenium-rich particles were detected. Furthermore, the particles existed within both elongated gamma prime and gamma phases, and even at their boundary. Based on experimental observations, the formation mechanism of this intermediate layer was discussed.

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Section: Methodsmentioning

confidence: 99%

Section: A Possibility Of Cellular Recrystallization or Formation Ofmentioning

confidence: 99%

Formation of an Intermediate Layer Between Grains in Nickel-Based Superalloy Turbine Blades

Kim

Withey

2017

Metall Mater Trans A

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“…However, cooling rates over 1°C/s are difficult to obtain with this type of furnace at the temperature levels considered in this study. During the time needed to cool down the material to 1050°C, massive dissolution of the γ' reinforcing phase takes place first, followed by a delayed reprecipitation of cubic nanometric precipitates in the γ channels [13]. In this context, failure is observed within minutes after the overheating has occurred [14].…”

Section: Experimental Techniquesmentioning

confidence: 99%

“…This produces non-isothermal creep conditions with the load only slightly increasing as the engine speed increases slightly, while the temperature varies due to the OEI simulation. In this context, long exposures of superalloys to extreme temperature are well documented in the literature [5,[13][14][15][16][17]: it provokes the dissolution of the γ' reinforcing phase and induces a severe loss in mechanical properties. In contrast, little is known about the mechanical behavior when the material is exposed to very high temperature transients, particularly when under load.…”

Section: Introductionmentioning

confidence: 99%

Non-Isothermal Creep Behavior of a Second Generation Ni-Based Single Crystal Superalloy: Experimental Characterization and Modeling

Cormier¹,

Milhet²,

Vogel³

et al. 2008

Superalloys 2008 (Eleventh International Symposium)

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In order to simulate emergency regimes possibly encountered by turboshaft engines for helicopter, non-isothermal creep behavior of the second generation single crystal Ni-Based superalloy MC2 was investigated. These tests were performed with one short overheating at 1200°C during the isothermal creep life of the material at 1050°C. Overheatings were carried out using a burner rig designed to achieve temperature jumps as fast as 60°C/s in the range 1050°C-1200°C. Both the overheating duration and its position during the isothermal creep life at 1050°C of the material have a great effect on the non-isothermal creep behavior. The modifications in creep behavior were clearly linked with microstructural evolutions occurring during temperature changes, e.g: the dissolution of the γ' phase on heating the material and the dislocation recovery processes.Based on these microstructure characterizations, a classical macroscopic model involving isotropic variables and a von Mises criterion was enhanced with the addition of new internal variables representative of the γ'-volume fraction and a recovery function attesting for the dislocation activity.

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“…At 1210 • C, the model underestimates the average radius of the precipitates, but the qualitative evolution ofR V at long ageing times is well reproduced. The onset of precipitation has been [23]. It varies between 1250 and 1270 • C, depending on the cooling rate.…”

Section: Comparison Of the Psd Simulations With Experimental Resultsmentioning

confidence: 99%

Numerical simulation of AM1 microstructure

Rougier

Jacot

Gandin

et al. 2014

MATEC Web of Conferences

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Abstract.A modelling approach is developed for the description of microstructure formation in the industrial AM1 Ni-base superalloy. Solidification and homogenization simulations are first carried out using a microsegregation model, before using the local compositions as an input for precipitation calculations, in order to characterize the influence of segregation on precipitation. First, the precipitation model was validated by comparing simulated and measured evolutions of the average precipitate radius during isothermal heat treatments at 1100 • C and 1210 • C. The chained microsegregation and precipitation simulations indicate that the global sequences of precipitation events remains are qualitatively the same at the different locations in the microstructure, but the growth and dissolution kinetics are strongly influenced by the local compositions. Local supersaturations have a larger effect on the average radius of the precipitates than certain stages of the precipitation heat treatment.

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Precipitation and dissolution processes in γ / γ ′ single crystal nickel-based superalloys

Cited by 212 publications

References 36 publications

Formation of an Intermediate Layer Between Grains in Nickel-Based Superalloy Turbine Blades

Formation of an Intermediate Layer Between Grains in Nickel-Based Superalloy Turbine Blades

Non-Isothermal Creep Behavior of a Second Generation Ni-Based Single Crystal Superalloy: Experimental Characterization and Modeling

Numerical simulation of AM1 microstructure

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