scholarly journals Modeling of Precipitation Kinetics of TCP-Phases in Single Crystal Nickel-Base Superalloys

2011 ◽  
Vol 278 ◽  
pp. 180-185 ◽  
Author(s):  
Ralf Rettig ◽  
Astrid Heckl ◽  
Robert F. Singer
Keyword(s):  
Single Crystal ◽  
Multicomponent Diffusion ◽  
Interface Energy ◽  
Precipitation Process ◽  
Precipitation Model ◽  
Mobility Database ◽  
Tcp Phases ◽  
Tcp Phase ◽  
Nickel Base ◽  
Kinetics Of

The precipitation of brittle so-called TCP-phases is critical for the application of Re-containing single crystal superalloys. In this work a fully multicomponent precipitation model is presented, which is capable of simulating the precipitation process of the TCP-phases in superalloys considering complex precipitation sequences with several metastable phases. The model is coupled to multicomponent thermodynamic CALPHAD calculations and relies on multicomponent diffusion models based on the TC-API interface of the software DICTRA. The required mobility database has been newly developed and covers all relevant alloying elements of the Ni-base superalloys including rhenium (Re) and ruthenium (Ru). It is well known that adding Ru strongly reduces TCP-phase precipitation. Based on the developed precipitation model, possible mechanisms are investigated to explain this effect and it is concluded that Ru mostly influences the nucleation rate by a combined influence on interface energy, “reverse partitioning” and γ’-phase fraction.

scholarly journals A Study of the Effects of Alloying Additions on TCP Phase Formation in 4th Generation Nickel-Base Single-Crystal Superalloys

2011 ◽  
Vol 278 ◽  
pp. 54-59 ◽  
Author(s):  
H.T. Pang ◽  
R.A. Hobbs ◽  
Howard J. Stone ◽  
Catherine M.F. Rae
Keyword(s):  
Single Crystal ◽  
Detailed Analysis ◽  
Phase Formation ◽  
Environmental Performance ◽  
Elevated Temperatures ◽  
Turbine Blades ◽  
Alloying Additions ◽  
Tcp Phases ◽  
Tcp Phase ◽  
Nickel Base

The demand for higher engine operating temperatures to improve aeroengine efficiency has meant that increasing levels of alloying additions are being added to single-crystal nickel-base superalloys for turbine blades applications. Whilst better mechanical and environmental performance may be obtained with these alloying additions, they also destabilise the alloys forming topologically closed-packed (TCP) phases. In this study, the formation of TCP phases has been studied in a series of four alloys designated LDSX1-4 which have a systematic variation in the levels of Co, Mo and W. The alloys were exposed to elevated temperatures between 900-1100°C for up to 1000 hours. This was followed by detailed analysis of the microstructures in the SEM. Identification of the TCP phases in selected alloys was also carried out. The effects of each alloying addition on TCP phase formation is discussed in light of these results.

The Microstructure Evolution of a Nickel-Base Single Crystal Superalloy after Long-Term Aging

2015 ◽  
Vol 1088 ◽  
pp. 217-220 ◽  
Author(s):  
Yu Xian Jia
Keyword(s):  
Single Crystal ◽  
Exposure Time ◽  
Microstructure Evolution ◽  
Ageing Time ◽  
Thermal Exposure ◽  
Single Crystal Superalloy ◽  
Phase Precipitation ◽  
Tcp Phase ◽  
Nickel Base

Microstructure evolution of a nickel-base single crystal superalloy during thermal exposure at 982°C was investigated. The SEM studies revealed that the size of γ' phase increased and some of which linked together with the elongation of the exposure time. There is acicular phase precipitation after the long-term ageing treatment. The TCP phase is not increased by the increment of ageing time after reaching a certain amount. There are skeleton shape carbides precipitate after 100h and 300h. The amount of precipitated carbides decreases by the elongation of ageing time.

Microstructure Development of an Electroplating Coated Nickel-Base SC Superalloy in Oxidation Processes—Simulation Results

2021 ◽  
Author(s):  
Kang Yuan ◽  
Zhaoran Zheng
Keyword(s):  
Kinetic Model ◽  
Single Crystal ◽  
Diffusion Zone ◽  
Microstructure Development ◽  
Diffusion Kinetic ◽  
Oxidation Processes ◽  
Secondary Reaction Zone ◽  
Tcp Phases ◽  
Simulation Results ◽  
Nickel Base

Abstract In this paper; a diffusion kinetic model was applied to simulate the microstructure development in a MCrAlY-superalloy system at high temperatures. Both simulation and experimental results showed that γ+γ’ microstructure was obtained in the coatings due to Al depletion after oxidation. With the help of the modelling; the mechanism of the formation of the diffusion zones in the single crystal (SC) superalloy can be also analyzed. The results revealed that the inward diffusion of Al from coating affected the depth of secondary reaction zone (SRZ) with the precipitation of TCP phases while the depth of inter-diffusion zone (IDZ) was decided by the inward diffusion of Cr.

Characterisation of the Structure of Single-Crystal Nickel-Base Superalloys

2010 ◽  
Vol 638-642 ◽  
pp. 2227-2232 ◽  
Author(s):  
Alexander Epishin ◽  
Thomas Link ◽  
Udo Brückner
Keyword(s):  
Single Crystal ◽  
Dendritic Structure ◽  
Experimental Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Base Superalloys ◽  
Nickel Base ◽  
Kinetics Of ◽  
Morphology Changes ◽  
Sem Investigation

New experimental methods developed by the authors for characterisation of the structure of single-crystal nickel-base superalloys are presented: X-ray diffraction at defined areas of the dendritic structure, none destructive SEM investigation of ’-morphology changes for different creep stresses and times with one specimen, and high resolution SEM investigations of dislocations in the ’-interfaces. Application of these techniques allowed to obtain new results, e.g. about the mosaicity of dendritic subgrains, distribution of the ’-misfit within a single dendrite and kinetics of rafting during creep in the superalloy CMSX-4 in wide temperature and stress ranges.

Effect of Ru on Microstructure of a Single Crystal Nickel-Base Superalloy

2007 ◽  
Vol 546-549 ◽  
pp. 1195-1200 ◽  
Author(s):  
Wen You Ma ◽  
Ya Fang Han ◽  
Shu Suo Li ◽  
Yun Rong Zheng ◽  
Sheng Kai Gong
Keyword(s):  
Growth Rate ◽  
High Temperature ◽  
Single Crystal ◽  
Nickel Base Superalloy ◽  
High Temperature Exposure ◽  
Refractory Elements ◽  
Tcp Phase ◽  
Nickel Base ◽  
Temperature Exposure ◽  
Base Superalloy

The effect of Ru on the microstructure of a high content refractory elements nickel base Superalloy has been studied in the present investigation. The results showed that, the adding of 3%Ru did not prevent the precipitation of TCP phase during high temperature exposure, and even accelerated the formation of TCP phase,however the addition of Ru decreased the growth rate of μ phase significantly. In addition, the adding of Ru decreased the solving temperature of γ/γ′ eutectic by 5°C, and increased the tendency of γ′ rafting during high temperature exposure.

Numerical simulation of γ/γ′ microstructural evolutions induced by TCP-phase in the MC2 nickel base single crystal superalloy

2011 ◽  
Vol 528 (6) ◽  
pp. 2620-2634 ◽  
Author(s):  
J.-B. le Graverend ◽  
J. Cormier ◽  
P. Caron ◽  
S. Kruch ◽  
F. Gallerneau ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Single Crystal ◽  
Single Crystal Superalloy ◽  
Tcp Phase ◽  
Nickel Base

Alloy Phase Stability Requirements in Single Crystal Superalloys

1990 ◽  
Vol 186 ◽  
Author(s):  
David N. Duhl
Keyword(s):  
Single Crystal ◽  
Phase Stability ◽  
Elevated Temperatures ◽  
Engine Performance ◽  
Two Phase ◽  
Gamma Prime ◽  
Tcp Phases ◽  
Nickel Base ◽  
Alloy Properties ◽  
Electron Vacancy

AbstractAlloy phase stability is a critical parameter in the design and implementation of nickel-base superalloys. To achieve the high temperature properties required of single crystal superalloys for application in gas turbine machinery, these alloys must have a stable gamma plus gamma prime microstructure for long periods of time at elevated temperatures. Significant deviation from this stable two phase microstructure, due to the precipitation of other phases, results in the loss of critical alloy properties which can have a deleterious impact on engine performance.Empirical methods based on the electron vacancy concept, commonly employed to predict and prevent the formation of undesirable topologically close packed (TCP) phases such as sigma or mu in polycrystalline nickelbase superalloys, are also used with single crystal superalloys. These undesirable phases result in the loss of alloy properties primarily as a result of the depletion of refractory strengthening elements from the superalloy matrix. The consequence of the formation of undesirable TCP phases on alloy properties and subsequent single crystal component behavior is reviewed.

The Influence of Thermal Exposure on the Microstructure Evolution of a Nickel-Base Single Crystal Superalloy

2011 ◽  
Vol 418-420 ◽  
pp. 265-269
Author(s):  
Yu Xian Jia ◽  
Tao Jin ◽  
Jin Lai Liu
Keyword(s):  
Single Crystal ◽  
Exposure Time ◽  
Microstructure Evolution ◽  
Thermal Exposure ◽  
Single Crystal Superalloy ◽  
Matrix Channel ◽  
Oriented Samples ◽  
Tcp Phase ◽  
Nickel Base ◽  
Sem Studies

Microstructure evolution of a nickel-base single crystal superalloy on the [001], [011] and [111] orientation during thermal exposure at 1000°C was investigated. The SEM studies revealed that the size of γ' phase increased and some of which linked together with the elongation of the exposure time. After 1100h the cubic γ' phase hardly is observed, and the rafting structure becomes perfect. With growing and linking of γ' phase the γ matrix channel is widening gradually, and the direction of γ' rafts is not along one define orientation. The TCP phase is not found in the three oriented samples during the thermal exposure.

Influence of Mo Addition on a Nickel-Base Single Crystal Superalloy

2014 ◽  
Vol 989-994 ◽  
pp. 264-266
Author(s):  
Kai Zhao
Keyword(s):  
Single Crystal ◽  
Rupture Strength ◽  
Lattice Misfit ◽  
Creep Rupture ◽  
Single Crystal Superalloy ◽  
Material Failure ◽  
Creep Rupture Strength ◽  
Tcp Phase ◽  
Nickel Base

The influence of minor Mo addition on the lattice misfit and creep rupture strength of a new single crystal superalloy have been investigated. It was shown that Mo can reduce the lattice misfit; increase the tendency of forming TCP phase; extend the time to material failure.

Effect of Long-Term Aging on the Evolution of γ' and TCP Phases of a Ni3Al Based Single Crystal Superalloy

2016 ◽  
Vol 849 ◽  
pp. 482-487 ◽  
Author(s):  
Xin Zhou ◽  
Jie Xiao ◽  
Yan Ling Pei ◽  
Shu Suo Li ◽  
Sheng Kai Gong
Keyword(s):  
Single Crystal ◽  
Volume Fraction ◽  
Thermal Exposure ◽  
Single Crystal Superalloy ◽  
High Temperature Strength ◽  
Coarsening Behavior ◽  
Heat Treated ◽  
Tcp Phases ◽  
Tcp Phase

The coarsening behavior of γ' phase and precipitation behavior of TCP phase in a Ni3Al based single crystal superalloy were investigated by experimental and calculation. The Re-containing and Mo-rich single crystal superalloy used in this study exhibit good high-temperature strength and oxidation resistance. After fully heat-treated, the experimental superalloys were aged at 1050°C and 1150°C for different time periods from 50h to 1000h. The microstructure after thermal exposure was examined by field emission-scanning electron microscopy (FE-SEM). The results indicated that the coarsening behavior of γ' phase agrees well with the typical Lifshitz-Slyozov-Wagner (LSW) theory. After thermal exposure, both the size and the volume fraction of the TCP phase changed perceptibly.

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