Atom Probe Analysis of the Compositions of γ′ AND γ″ Intermetallic Phases in Nickel-Based Superalloy 718

1990 ◽  
Vol 186 ◽  
Author(s):  
M. K. Miller ◽  
M. G. Burke
Keyword(s):  
Heat Treatment ◽  
Atom Probe ◽  
Nickel Base Superalloy ◽  
Probe Field ◽  
Nickel Based Superalloy ◽  
Transmission Electron ◽  
Transmission Electron Microscopy Characterization ◽  
Nickel Base ◽  
Microscopy Characterization ◽  
Base Superalloy

AbstractAn atom probe field ion microscopy and transmission electron microscopy characterization has been performed on the intragranular precipitates that are formed in a niobium-modified nickel-base superalloy 718 after the various stages of a multistage heat treatment. Atom probe results indicate that there is a wide variation in the compositions of the DO22-ordered γ″, the Ll2-ordered γ′ precipitates and the γ matrix with heat treatment and with position in the microstructure.

Long-Term Gamma Prime Phase Stability after Various Heat Treatment Conditions with Temperature Dropping during Solution Treatment in Cast Nickel Base Superalloy, Grade Inconel-738

2017 ◽  
Vol 891 ◽  
pp. 420-425
Author(s):  
Sureerat Polsilapa ◽  
Aimamorn Promboopha ◽  
Panyawat Wangyao
Keyword(s):  
Heat Treatment ◽  
Turbine Blades ◽  
Solution Treatment ◽  
Nickel Base Superalloy ◽  
Gamma Prime ◽  
Nickel Based Superalloy ◽  
Treatment Conditions ◽  
Nickel Base ◽  
Base Superalloy

Cast nickel based superalloy, Grade Inconel 738, is a material for turbine blades. Its rejuvenation heat treatment usually consist of solution treatment condition with temperature range of 1125-1205 oC for 2-6 hours. Then it is following with double aging process including primary aging at 1055oC for 1 hour and secondary aging at 845oC for 24 hours. However, the various selected temperature dropping program were performed during solution treatment to simulate the possible error of heating furnace. The maximum number of temperature dropping during solution treatment is varied from 1-3 times From all obtained results, the various temperature dropping during solution treatment conditions showed extremely the significant effect on the final rejuvenated microstructures and long-term gamma prime stability after heating at temperature of 900oC for 200 hours.

Effect of Pre-Weld Heat Treatment Temperatures on TIG Welded Microstructures on Nickel Base Superalloy, GTD-111

2015 ◽  
Vol 658 ◽  
pp. 14-18
Author(s):  
Tanaporn Rojhirunsakool ◽  
Duangkwan Thongpian ◽  
Nutthita Chuankrerkkul ◽  
Panyawat Wangyao
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Heat Treatment Temperature ◽  
Treatment Temperature ◽  
Tig Welding ◽  
Nickel Base Superalloy ◽  
Nickel Base ◽  
Base Superalloy ◽  
Weld Heat

Nickel-base superalloys have been used as high temperature materials in land-base gas turbine application. When subjected to long term, high temperature service, large crack propagation was observed. Typical refurbishment method of these turbines is carried out by using TIG welding followed by post-weld standard heat treatment. However, new crack initiation is found in the heat-affected zone after TIG welding. Pre-weld heat treatment has been discovered to improves final γ + γ’ microstructure. This study focuses on the effect of pre-weld heat treatment temperature on final γ + γ’ microstructure. Seven different conditions of pre-weld heat treatment temperature were investigated. Scanning electron microscopy studies were carried out after pre-weld and post-weld heat treatments to compare the γ + γ’ microstructure and capture microcracks. The best pre-weld heat treatment temperature produces uniform distribution of finely dispersed γ’ precipitates in the γ matrix without post-weld crack.

scholarly journals Effect of Heat Treatment Process on Microstructure and Fatigue Behavior of a Nickel-Base Superalloy

Materials ◽  
2015 ◽  
Vol 8 (9) ◽  
pp. 6179-6194 ◽  
Author(s):  
Peng Zhang ◽  
Qiang Zhu ◽  
Gang Chen ◽  
Heyong Qin ◽  
Chuanjie Wang
Keyword(s):  
Heat Treatment ◽  
Treatment Process ◽  
Fatigue Behavior ◽  
Nickel Base Superalloy ◽  
Heat Treatment Process ◽  
Nickel Base ◽  
Base Superalloy

Application of Atom Probe Microanalysis for Understanding Microstructure Evolution in Nickel Base Superalloy Welds

2000 ◽  
Vol 6 (S2) ◽  
pp. 350-351
Author(s):  
S. S. Babu ◽  
S. A. David ◽  
M. K. Miller
Keyword(s):  
Microstructure Evolution ◽  
Predictive Models ◽  
Strong Relationship ◽  
Atom Probe ◽  
Systematic Investigation ◽  
Nickel Base Superalloy ◽  
Cooling Conditions ◽  
Nickel Base ◽  
Base Superalloy

The characterization of the microstructure evolution during welding of nickel base superalloys is required for efficient reuse and reclamation of used and failed components. Previous atom probe analysis of electron-beam and laser-beam welds revealed complex alloying elemental partitioning between the γ and γ phases. Rapid cooling conditions in the weld leads to non-equilibrium partitioning and large amplitude Cr and Co levels in the γ phase. These results indicated that there is a strong relationship between weld cooling rate and the precipitation of γ′ precipitates from the γ phase. To understand and develop predictive models, a systematic investigation of the microstructure evolution in CM247DS alloy under controlled thermomechanical conditions are being performed. This paper describes some recent results on the elemental partitioning between γ and γ′ phases obtained with atom probe microanalysis.

Morphology of Precipitates in Ni-Al-Cr Intermetallic Alloy

2007 ◽  
Vol 130 ◽  
pp. 159-162
Author(s):  
Mirosław Pilawa ◽  
Elżbieta Jezierska
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intermetallic Alloy ◽  
Nickel Base Superalloy ◽  
Transmission Electron ◽  
Characteristic Features ◽  
Secondary Precipitates ◽  
Nickel Base ◽  
Base Superalloy

Transmission electron microscopy was used to study various morphologies of ordered precipitates in Ni3Al-Cr intermetallic alloy. It was found that γ’ precipitates in the interdendritic regions have the microstructure of a nickel base superalloy with its characteristic features. In addition to the primary γ’ precipitates some fine secondary precipitates were found.

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